emergency lighting. for industrial, commercial and residential premises

EMERGENCY LIGHTING

For industrial, commercial and residential premises

Stanley Lyons

U T T E R W O R T H I N E M A N N

Butterworth-Heinemann Ltd Linacre House, Jordan Hill, Oxford OX2 8DP

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First published 1992

© Butterworth-Heinemann Ltd 1992

All rights reserved. No part of this publication may be reproduced in any material form (including photocopying or storing in any medium by electronic means and whether or not transiently or incidentally to some other use of this publication) without the written permission of the copyright holder except in accordance with the provisions of the Copyright, Designs and Patents Act 1988 or under the terms of a licence issued by the Copyright Licensing Agency Ltd, 90 Tottenham Court Road, London, England W1P 9HE. Applications for the copyright holder's written permission to reproduce any part of this publication should be addressed to the publishers

The author asserts his moral right to be identified as the author of this work.

British Library Cataloguing in Publication Data Lyons, Stanley L.

Emergency Lighting: For Industrial, Commercial and Residential Premises I. Title 621.32

ISBN 0 7506 0806 4

Composition by Genesis Typesetting, Laser Quay, Rochester, Kent Printed and bound in Great Britain by Biddies Ltd, Guildford and King's Lynn

Preface

This book deals with emergency lighting for industrial, commercial and residential premises (but not cinemas and places of public entertainment). Although emergency lighting is not a separate subject from the other lighting of premises, a book dealing specifically with emergency lighting is justified because the subject is of such importance to the safety of occupants.

In the UK, both Statute and Common Law place upon occupiers of business premises a responsibility to provide 'sufficient and suitable lighting' to ensure the reasonable safety of persons entering their premises, and this includes a requirement to provide emergency lighting to enable persons to escape from premises if the normal lighting should fail due to any reason. In accord with current thinking, this book also deals with the subject of 'way-guiding', i.e. methods of giving escape-route guidance to persons if the normal lighting or emergency lighting is functioning but its light is obstructed by dense smoke etc.

It is recommended that this book should be read in conjunction with BS.5266 Part 11988, with CIBSE Technical Memoranda TM-12 and other relating TMs, as well as the relevant ICEL publications which are given as references; for, while I discuss, explain and augment the data from those publications, I do not repeat their content.

The text refers to UK practices and, because of harmonization of standards, in general these will be in accord with those of other EC countries. During the currency of this book, some UK laws relating to the provision of lighting and for ensuring the safety of persons will undergo changes because of further harmonization. As far as is possible, the general nature of such new requirements has been described, and ample references provided.

As well as describing accepted general practice, this book also describes a number of provisions for emergency lighting (especially for aiding escape in conditions of smoke, and for finding a safe path in outdoor environments) which are the author's own proposals

x Preface

which at present do not form part of any agreed standard, and these are so identified in the text.

Safety practices and engineering procedures in the UK do not differ basically from those in the USA, Canada, New Zealand and Australia, but users, specifiers and installers should ensure that all practices and installations comply with local standards and legisla-tion.

It would be misleading to discuss emergency lighting as though it were intended only to enable persons to escape from premises when the normal lighting fails, and without regard to other circumstances such as the outbreak of fire. Various sections of the book deal with matters of fire prevention and management, and the movement of persons along escape paths in conditions of low illuminance or poor visibility.

This book is mainly concerned with the provision of emergency lighting to enable the escape of persons from shops, offices, factories and other business premises, from residential premises including hospitals, from various kinds of workplaces, and from places to which the public have access; therefore much of the content is not applicable to ordinary domestic premises. However an appendix is provided which gives some guidelines on promoting the safety of persons in regard to escape from fire in ordinary family homes.

While providing an up-to-date review of emergency lighting practice for lighting engineers, electrical engineers, building services engineers, architects and designers, I have also tried to make this book intelligible to users of emergency lighting who may have no specialist knowledge of the subject. I have avoided the use of jargon, and have explained all special terms at their first use - a feature which will be of value to students and non-specialist readers.

Stanley Lyons

Note

In addition to a review of current practice in the field of emergency lighting, this book contains proposals for the development of novel equipment and the application of innovative methods. The book is intended for use by persons with appropriate qualifications in the relevant fields. In case of doubt, the user should obtain advice and assistance from a suitably qualified person before adopting any proposal made in this book. To the best of the author's and the publisher's knowledge the information in this book is accurate and up to date at the time of publication. However, neither the author nor the publisher can accept responsibility for any inaccuracy or error.

1 Introduction

For applications of emergency lighting in industrial premises, this book may be regarded as an appendix to the author's book Lighting for Industry and Security1 which contains basic information on the subject of emergency lighting which is much expanded here. The scope of the present book includes also emergency lighting for offices and commercial premises, for hotels and residential premises, for shops and shopping malls, and for stadia and other places of public assembly (but excluding emergency lighting in cinemas and places of public entertainment). This book may also be regarded as an appendix to another book by the author, Security of Premises - A Manual for Managers2, because emergency lighting - both indoors and outdoors - has important implications for security (see Section 1.3). Some guidelines on the promotion of safety of persons in regard to fires in domestic dwellings are given in Appendix C.

1.1 Objectives of emergency lighting systems

Emergency lighting is a vital facility to enable persons to escape from buildings when the normal lighting has failed. Failure of the normal lighting may occur during a fire or other emergency. Some 30,000 business premises are damaged by fire - or destroyed - in the UK every year. The risk of injury in a fire is high; including deaths and injuries due to fires in domestic dwellings (see Appendix C) the annual death toll in the UK is around 900, plus around 10,000 persons injured each year in fires. Emergency lighting, together with proper means of fire prevention, escape, and fire management, can help to reduce this suffering and loss of life.

Emergency lighting is either in continuous operation while the premises are occupied, or it comes into operation automatically immediately on failure of the normal lighting - or after a delay of a few seconds. The term 'emergency lighting' includes luminous signs and luminous way-guiding devices to aid escapers traverse an escape

2 Emergency Lighting

route when it is smokefilled (see Section 3.3 and Chapter 5). It also includes lighting which is provided to enable essential tasks to be carried out during a failure of the normal lighting.

1.2 Fire precautions and escape routes

Occupiers of business premises have specific duties under law in respect of providing means of escape from premises (see Sections 2.1 and 2.2). The Fire Precautions Act 1971 (FPA)3 specifies that unobstructed escape routes shall be provided from all parts of the occupied premises to a designated place of safety (see Section 3.7). Escape routes are required to be capable of use at all material times, thus creating the obligation to provide lighting that will enable persons to use the route safely during times when there is insufficient daylight for safe movement and the normal lighting is not operating due to any cause.

1.2.1 Fire precautions

The precautions necessary to reduce fire risk, to control the spread of fire, and to facilitate escape from burning premises will differ according to the nature of the premises and the risks inherent in its construction, its contents and its use. Guidance leaflets on fire precautions are available from the Loss Prevention Council and The Fire Protection Association (see Appendix B) who also provide training in fire prevention and control. There may be advantages in integrating some aspects of the emergency lighting system with systems of fire detection and control (see Section 8.4), and of security systems too (see Section 1.3).

Management action to reduce risk to personnel and to reduce risk of loss due to fire will consist of devising and practising good management and safety measures to cover such matters as are listed here in random order: • Devising and putting into effect measures to minimize the risk of

fire being caused (e.g. by devising or adopting safe processes; by training staff to avoid practices which are accompanied by risk of fire).

• Devising and putting into effect measures to reduce the growth and spread of fire (e.g. by locating dangerous processes where an

Introduction 3

outbreak of fire would produce less risk to personnel and less risk of rapid spread of fire; installing fire-resistant partitions and doors, etc).

• Devising and putting into effect measures to limit the spread of smoke (e.g. by installing self-closing devices on doors leading from work areas to escape corridors); by fitting automatic devices to control smoke (e.g. smoke canopies, smoke curtains), and fitting devices to vent smoke from the building (e.g. automatic-opening roof smoke vents, powered exhaust systems etc).

• Installing devices for the detection of smoke and fire and the automatic sounding of fire alarms; possibly providing means for the automatic transmission of a smoke or fire condition message to a central security monitoring station for onward transmission to fire brigade, security guarding agency and keyholders etc after confirmation of the condition by remote technical means (a procedure designed to minimize the occurrence of false alarms).

• Providing means for occupants to raise the fire alarm to warn other occupants.

• Providing firefighting equipment (e.g. fire blankets, extinguishers, hoses etc) and training personnel in its use.

• Devising plans for the rapid and safe evacuation of all persons from the premises along clearly defined escape routes should fire break out, and by training and fire drills to ensure that personnel understand what to do.

1.2.2 Escape routes

Measures to enable occupants to escape from the building in the event of fire or other emergency must include:

• the designation of exits which will enable escapees to reach a designated place (or places) of safety (see Section 3.7), and the clear marking of the exits by luminous signs (see Section 5.1).

• The designation of clearly defined escape routes, which shall be provided with escape emergency lighting to the requirements of BS 52664 (or such other standard acceptable to the enforcing authority and the insurers), and which shall be kept clear of obstructions. The emergency lighting shall reveal a safe passage-way, fire alarm call points, firefighting equipment and any permanent hazards (e.g. changes of direction, ramps, stairs etc).


1.3 Crime prevention implications of emergency lighting

The failure of lighting in any premises provides an opportunity for crime1'2. When the normal lighting fails, emergency lighting can serve the vital function of providing essential light at points of risk such as at tills in retails stores, at strongrooms, in banks and building society offices, at checkpoint huts where entry through a perimeter is controlled, and at vulnerable points in every kind of commercial, residential or industrial premises. Without at least a little light, personnel cannot even use the telephone for dealing with emergen-cies. So, as well as enabling persons to escape from premises (see Section 1.1), and enabling vital tasks to be continued (see Section 1.4), emergency lighting and standby lighting can also protect persons and property by performing a crime-prevention function, as well as enabling vital services such as security control rooms to remain in operation during a mains failure27. It is known for technical villains to cause a mains failure (typically by interfering with cables and electrical cubicles in underground car-parks) so that darkness will help them in their criminal attack.

It is also known for thieves to start fires in supermarkets and large stores (typically by setting newspapers alight in a toilet, on a stairway or in a cupboard) in the hope that a smoke alarm will be triggered and give them an opportunity to grab at a till in the ensuing confusion. Thieves have been known to interfere with lighting circuits to create a panic which they hope will divert the attention of staff so that an attack may be made on the cash room. For such reasons it is good practice to provide an enhanced level of emergency lighting local to tills and other vulnerable points in such premises, preferably by single-point self-contained luminaires.

1A Stand-by lighting

1.4.1 Security of power supplies

In the UK, the general standard of security of mains power supply is very high; however, certain locations which are fed by local overhead lines may be vulnerable to outages in conditions of bad weather.

Introduction 5

Mains electricity supplies to the normal lighting of premises may be made more secure by taking supplies from two feeders fed from different parts of the supply company's distribution network, though this may be a rather costly facility.

It is normal good practice to divide the distribution circuits within premises so that lighting loads are separate from power circuits, and to ensure that the subcircuits are adequately individually protected against overload. To reduce the risk of total blackout in a factory, supplies to luminaires in any area may be fed from two or three phases; this method of installation also minimizes stroboscopic effect1.

1.4.2 Effects of long outages

Good engineering and maintenance will reduce the risk of breakdown of lighting, but failure may be due to causes beyond the occupier's control, viz, fire in a plant room, or a failure of the mains supply.

Quite apart from emergency conditions due to fire and other dangers which may accompany - or be the cause of - a failure of lighting, a blackout in any workplace can have serious effects on profitability. In some plants, loss of the lighting for some hours would not only lose production, it could cause danger because activities such as chemical processes and the operation of high temperature plant simply cannot be stopped quickly without causing costly damage such as clogging of pipelines, or cracking of refractories or of retort linings. In other cases, loss may be an indirect result of lighting failure; for example, failure of just the outside lighting at a steelworks could bring the whole plant to a standstill in a few hours through an inability to move raw and finished materials into and out of the plant. Failure of security lighting could put a company at risk; such a failure at a key strategic target could have serious implications (see Section 1.3 and 8.4). On a civil engineering site, a long failure of lighting while casting a massive monolithic concrete structure might halt pouring and result in a weakened structure, so that the cost of such interruptions can be high. Loss of lighting on a construction site might throw a tightly scheduled programme of work off course and involve the contractor in penalties for late completion.

It seems that the UK construction industry has only recently


generally adopted the use of external site lighting as a means of ensuring and enhancing profitability1; it must be hoped that leading contractors will set an example to the industry by routinely providing emergency lighting too, or - at the very least - providing alternative means of lighting in the most dangerous situations and within unfenestrated structures (see Section 7.3).

While the prime function of emergency lighting is to enable persons to escape from premises during a failure of the normal lighting, we see that it may also enable essential things to be done during such a failure. If the duration of such activities is likely to be longer than the feasible duration of emergency lighting batteries, the emergency lighting or other lighting may be powered from an independent source of electrical power so as to provide illumination for a longer period, this being termed a stand-by power supply (see Section 6.3).

2 Legal requirements

2.1 Occupier's Common Law duties

Apart from UK and EC legislation which imposes specific duties upon occupiers of premises (see Section 2.2), the British Common Law embodies a principle that an occupier must take steps to ensure the reasonable safety of persons who enter his premises.

This legal precedent is capable of wide interpretation in the courts should an injured party (or his estate) claim damages following an injury or fatality occurring on the premises. In such a case, a good defence would probably be to show that there has been no neglect of duty. In a case in which it was claimed that an accident resulting in injury or death was caused or aggravated by the failure of the occupier to provide sufficient and suitable lighting, a good defence would be to show that the lighting of the premises at the material time complied with an accepted code of practice, i.e. that it complied with the recommendations of the Lighting Division of the Chartered Institution of Building Services Engineers (CIBSE) (see Appendix B) and of the relevant British Standards (see References).

Similarly, it may be argued that in performing his duty to provide sufficient and suitable lighting, the occupier would not be excused that duty because of any act or omission by a third party, e.g. if the power supply to the premises failed. It is therefore construed that the occupier has a duty under Common Law to provide emergency lighting. Further, the quality of his action in so doing must be assessed by the degree of compliance of the emergency lighting with an accepted code of practice, which, at the moment is BS 5266 Part

2.2 Duties of occupiers under UK and EC legislation

2.2.1 Fire Precautions Act 1971

The UK Fire Precautions Act (FPA)3 states in Chapter 40 that 'the means of egress shall be capable of use at all material times', and this is


construed to mean that lighting shall be provided along escape routes to enable persons to use them to reach a designated place of safety. Many industrial premises in the UK were equipped with emergency lighting before the FPA made the provision of such equipment in business premises mandatory. The life-saving value of such lighting is clearly established. Management's task is to determine the nature of the emergency lighting system that will best serve the needs of their organization, and to seek out those methods of emergency lighting which, while complying with the law, are economical, easy to maintain, and will give long technical life.

The UK Factories Act 19616 has largely been replaced with new regulations under the Health & Safety at Work Act 1974 (HASAWA)7. Many remaining provisions will be replaced by new EC-harmonized regulations in 1993, and in the next few years the Factories Act will disappear. HASAWA extends the general duty of care that occupiers of business premises must exercise to protect persons on their premises from harm (see Section 2.1), and imposes a further duty on occupiers to demonstrate that they have complied with the requirements of the FPA3. Inspectors appointed under the FPA are empowered to issue Fire Certificates which signify that proper fire precautions have been instituted, and that facilities for the speedy and safe evacuation of the premises (including the provision of suitable emergency lighting) are in place.

The occupier would not be excused his duty to provide lighting for escape because of failure of another party to perform any act, e.g. if the mains electricity failed; so the need for independently powered emergency lighting is clearly established as a legal obligation. With certain exceptions, without a valid Fire Certificate, the premises may not be occupied; however, Fire Certificates are not required for factories or offices etc in which: • not more than 20 persons are at work at any one time, and • not more than 10 persons are at work at any one time elsewhere

than on the ground floor. The above exemptions do not apply to premises in multiple occupancy where the aggregate number of persons at work in the premises exceeds the above numbers, nor does it apply to premises where highly dangerous materials are stored or used. The fire authority has power to decide if materials are 'highly dangerous', and if they are present in sufficient quantity to justify the requirement for

Legal requirements 9

a Fire Certificate even if less than the stipulated numbers are employed. Conversely, for certain low-risk premises, the fire authority has the discretion to grant exemption from the need for a Fire Certificate, even though the actual numbers of persons working on the premises may exceed the normal limits for exemption. The current technical standards for emergency lighting4 (see Chapter 10) imposed under the FPA3 and the rules for their application may be modified by future EC-harmonized legislation.

The inspector who authorizes the issue of Fire Certificates for workplaces may currently be the Fire Prevention Officer of the local fire brigade, but in the future is likely to be a building inspector appointed by the Local Authority. In either case, such officers are valuable sources of information and practical advice regarding the prevention of fire, the management of fire situations and the evacuation of premises; they may not, however, be able to advise on the technology of emergency lighting systems and the selection of equipment.

Because it is costly to provide illumination from battery supplies, escape lighting employs very small illuminances which are just adequate to enable dark-adapted persons having normal vision to see well enough to find their way out of the premises.

Few people outside of the lighting profession have detailed knowledge about visibility at low lighting levels; it might be imagined that each enforcing officer who is responsible for issuing Fire Certificates under the FPA would have his own ideas about how escape lighting should be engineered, and to some extent this is true. The enforcing officers work generally within the guidelines of BS 52664 which has acquired something like the force of law; for under the FPA the enforcing authorities may take such a document as a Code of Practice to decide how the requirements of the FPA shall be met. (In the same way, the CIBSE Code8 serves the purpose of a Code of Practice in relation to enforcement of HAS AW A; although the Code is not a legislative document, in effect its recommendations are enforceable by HSE Inspectors, i.e. a good defence against a charge of failing to provide 'sufficient and suitable lighting' would be to demonstrate that the lighting complied with the Code.)

There is currently much concern about the qualifications of inspecting officers and their competence to determine if a system of emergency lighting is satisfactory. Several hundred local government officers are empowered to carry out these inspections, yet it is


understood that nationwide only a few of them have suitable low-reading lightmeters with which to measure the illuminance of the installations. Further, it is understood that very few tests are actually carried during the hours of darkness when such measurements can be made.

Under current law in the UK, once the Fire Certificate has been issued, the responsibility for ensuring the proper maintenance and care of the installation passes to the occupier; but no further inspections are carried out by the enforcing officer to ascertain if that duty is being properly performed. Indeed, the only time the certificates required under BS 5266 might be officially inspected would be in the very unlikely event of a coroner calling for them to be submitted as evidence in an inquest upon the death of a person on the premises. Perhaps there should be an inquest on every fire (as there is in some countries).

In this book, proposals are made for installing low-mounted luminous way-guidance systems to enable persons to escape from premises in conditions of smoke (see Sections 3.2 and 3.3). Until way-guidance devices become an accepted part of emergency lighting practice (as it is believed they will), it is proposed that, if the luminous guidance devices would not produce illuminances as required by BS 5266 (i.e. 0.2 lux minimum along the centrelines of escape routes) when the escape corridor is smokefilled, way-guidance could be employed in addition to conventional emergency lighting.

Careful study of the regulations is necessary to ensure that all legal obligations regarding fire are properly discharged. A convenient reference is the publication Guide to fire precautions in existing places of work9. A wide range of useful publications dealing with fire precautions and loss prevention for many types of premises is available from the Fire Protection Association and the Loss Prevention Council (see Appendix B).

2.2.2 Current technical standards in the UK

The important current references to the subject of emergency lighting are: • BS 52664; this serves the purpose of a code of practice and contains

much wise guidance; but it does not provide sufficient information


to enable the detailed design of emergency lighting systems to be carried out;

• CIBSE Technical Memorandum TM-1210 which gives technical guidance on applications and design of emergency lighting systems;

• ICEL:1003/Lighting Industry Federation Application Guide11. which covers much of the same ground as the foregoing but is concerned in more detail with the construction and performance of emergency lighting in specific locations; and

• CIBSE Lighting Guide LG0623 which makes recommendations for emergency lighting in outdoor environments, e.g. stadia and public places.

2.2.3 Technical standards, 1992 onward

Technical and legal requirements for emergency lighting and safety signs in the UK will undergo significant change in future as a result of integration and harmonization of standards within the EC. It is believed that the most significant changes will be in respect of safety of emergency lighting systems and in control of electromagnetic contamination (radio interference).

At the time of writing, it is understood that directives have been issued by the European Commission in respect of the following:

• Low Voltage Directive, concerned with electrical safety. (The present directive may be extended.)

• Work Place Directive concerned with safety in the workplace, and including exit signs, safety signs and emergency lighting in workplaces. (Introduction date 31 December 1992.)

• Construction Products Directive, which lays down methods of making buildings safer; and specifying the design of escape routes, lighting and other matters. (Introduction date 27 December 1991.)

• Safety Signs Directive. (Introduction date 1 January 1994.)

The above Directives will be interpreted by CENELEC as European Norms and transposed into National Standards, at which point each EC government must introduce legislation for their enforcement.


2.2.4 Future legislation

Notwithstanding the importance of the responsibility of the occupier under Common Law (see Section 2.1), it is stressed that while there are ten Acts of Parliament covering fire safety, and many statutory instruments, codes of practice and technical memoranda, emergency lighting is still not specifically required by statute in the UK. At the time of writing there is considerable pressure from the lighting industry to bring this about. Ernest Magog, director of the Lighting Industry Federation (see Appendix B) has stated that 'We will be making representations to Brussels to push for the necessary legislation'5.

2.2.5 Signs and symbols

In an attempt to ensure that safety signs are easily understood by persons speaking any language, and by the illiterate, an important change in practice is the adoption of illuminated signs with symbols. Consequently, the former requirements of BS 5499:1980 and BS 5260:1978 as regards externally and internally illuminated signs are replaced by those of BS 5499.199012. Exit signs are now required to show a graphic symbol or 'exit pictogram' (see Section 5.2.3). For a time, the word ΈΧΓΓ will continue to be used, but will probably be dropped in the future.

Even before it has been generally adopted, the 'running man' pictogram has its critics, and alternative signing methods for future adoption are being discussed (see Section 5.2.3).

2.2.6 Escape route guidance

Important developments are afoot regarding the development of illuminated means of guiding persons along escape routes in conditions of smoke when visibility is very limited. In these conditions, low-mounted luminous way-guidance devices may be used (see Section 5.4), and luminous devices may be recessed into the floor or stair nosings to give guidance in darkness and smoke to a person crawling towards safety; a system of low-mounted floor floods is under discussion (see Section 4.3); illuminated handrails giving


illumination and physical guidance in situations such as on underground railway platforms, stairs, inclines, etc (see Section 5.4) are being adopted.

Current thinking is to press the international standards-makers and legislators to set emergency lighting standards similar to those widely employed in passenger aircraft, in which it is recognized that the build-up of smoke in a fire can rapidly make conventional high-mounted exit signs unreadable.

2.3 Contractual responsibilities

The occupier of premises should note that the following conditions may oblige him to provide emergency lighting: • Contractors and subcontractors working on any premises are

entitled to the duty of care on the part of the legal occupier under Common Law and legislation. This will usually involve the provision of emergency lighting by the occupier. Note that during a construction or refurbishment contract, the main contractor may be held to be the occupier until he hands over the premises to the future occupier.

• Electrical installation contractors engaged in installing, repairing or maintaining emergency lighting on any premises are to be provided with sufficient and suitable lighting for their safety while working and to enable them to escape from the premises. This might place upon the contractor a duty to bring to site suitable temporary or portable lighting for use while he is engaged on work in premises in which there is no emergency lighting or when such emergency lighting is not in working condition (see Section 7.5).

• In some organizations the electrical supplies to the emergency lighting system are routinely switched off when the premises are not occupied. However, the presence of persons such as security guards and cleaners on the premises (be they employed by the occupier or employed by contractors) will necessitate the provision of lighting for their safety, and of emergency lighting to enable them to escape from the premises if the normal lighting should fail (see Section 8.3).


2.4 Tenancies; shared and adjacent premises

Unless otherwise determined by terms of an agreement or lease, premises that are partly let or let to two or more other parties will usually involve the landlord being responsible for the installation and maintenance of normal lighting and emergency lighting of stairways and common access areas. Similarly, a tenant who is the sole occupant of only part of a premises will usually be responsible for the normal lighting and emergency lighting in that part of the premises which he occupies.

At adjacent premises which share a common access area over which the occupiers have right-of-way, it must be determined which party or parties shall be responsible for the normal lighting and emergency lighting of such an area. It is common for the occupant or owner of one of the premises to undertake the task of providing the normal lighting and emergency lighting of the common access areas, the cost being shared between the parties who jointly use such areas.

2.5 Nuisance

Because the brightness and lighting levels produced by emergency lighting are low, emergency lighting systems rarely cause any nuisance. However, 'maintained' or 'combined' emergency lighting luminaires (i.e. those that are always illuminated; see Section 4.2) could cause difficulties in an industrial or scientific work area in which tasks have to be carried out in very low illuminance.

Exterior emergency lighting (see Section 3.5) could cause nuisance to occupants of adjoining premises, and the luminaires might have to be screened or positioned with care to prevent this. Cases have occurred where neighbours have claimed that external lighting (including emergency lighting) has caused nuisance, particularly in country areas where the district brightness is low. For example, it has been claimed that stray light has affected the laying cycle of hens on adjacent property.


2.6 EC requirements for integral machine lighting

The provision of integral lighting in machines in industry is already common; for example, lighting may be built into papermaking machines to enable the operator to enter the machine for the purposes of lacing-up or dealing with paper jams. Machine tools such as milling machines and lathes commonly are fitted with an integral lamp at the tool operating point. It is visualized that increasingly many highly localized forms of lighting will be provided in the form of fibre-optical devices (see Section 5.4).

An EC Council directive13 contains a requirement for lighting integral to certain machines which is provided for operator safety. The implementing provisions of this directive have been adopted, and it enters into force on 1 January 1993. However, until 31 December 1994, Member States must continue to permit machinery which complies with national legislation in force on 31 December 1992 to be placed on the market and put into service. The publication The Single Market - Machinery1*, published by the UK Department of Trade & Industry, states in Annex B:

The manufacturer must supply integral lighting suitable for the operations concerned where its lack is likely to cause a risk despite ambient lighting of normal intensity.

The manufacturer must ensure that there is no area of shadow likely to cause nuisance, that there is no irritating dazzle and that there are no dangerous stroboscopic effects due to the lighting provided by the manufacturer.

Internal parts requiring frequent inspection, and adjustment and maintenance areas, must be provided with appropriate lighting.

Referring to the risk of explosion it states:

Electrical equipment forming part of the machinery must conform, as far as the risk from explosion is concerned, to the provisions of the specific Directives in force.

A dangerous condition would exist if lighting that is provided integrally to ensure the safety of the operator of a machine should fail


while the electrical supply to the machine remained live. It is visualized that a form of emergency lighting might be employed, i.e. that the integral lighting might have its own emergency battery supply. The publication referred to states:

The battery housing must be constructed and located and the battery installed so as to avoid as far as possible the chance of electrolyte being ejected on to the operator . . . and to avoid the accumulation of vapours in places occupied by operators.

Machinery must be so designed and constructed that the battery can be disconnected with aid of an easily accessible device provided for that purpose.

While this book is concerned with emergency lighting to enable persons to escape from premises or to continue essential tasks during a failure of the normal lighting, the information in this section has been included for completeness, as its omission might have left some readers unaware of the requirements for the integration of emergency lighting equipment into certain machinery for the safety of operatives.

3 Safe movement at low lighting levels

3.1 Visual performance

A more extensive description of human vision, including adaptation to high and low brightnesses and the subject of glare, is given in another book by the author1.

3.1.1 Adaptation

The eye's adaptation to brightness takes place mainly within the retina. The diameter of the pupil of the eye varies in response to the brightness of the field of view, thus providing a coarse degree of adaptation which deals mainly with excesses of brightness and large changes of brightness.

In ordinary conditions the eye adapts to an intermediate state of brightness adaptation termed mesopic vision. If the brightness of part of the visual field is too great for the iris to deal with, the subject suffers the sensation of glare (see Section 3.1.3).

The passage from fully light-adapted (photopic vision) to fully dark-adapted state (scotopic vision) can take several hours, though most of the possible adaptation takes place in the first few seconds, and the process is substantially complete in a few minutes. Generally, adapting to dark conditions takes longer than adapting to bright conditions. The eye finds it difficult to cope with rapid increases in brightness when it is well advanced into dark-adaptation; thus, after a long period in darkness, a small lightsource (e.g. a candle flame) seems very bright.

If there are frequent significant changes in field brightness, or if the eye has to cope with very diverse brightnesses in the field observed, the subject may become confused and fatigued. Better visual conditions exist if the lighting is adequate in quantity for the visual


task, and is reasonably evenly distributed so that the luminance pattern in the field of view is not excessively contrasting.

In a low field brightness (say, at an illuminance of 5lux), perception of colour becomes defective. As the illuminance is reduced further and the eye enters the scotopic state, vision becomes entirely monochromatic, this being termed the Purkinje Effect.

Because of the phenomenon of adaptation, the eye tends to be a poor judge of brightness. Small differences of brightness in a field of view are difficult to detect; we need to make an object ten times brighter in order to perceive it to be twice as bright as it was before. A subject experiencing glare (see Section 3.1.3) is less able to distinguish small differences in brightness, i.e. his contrast sensitivity is reduced.

3.1.2 Uniformity

In ordinary lighting conditions, the eye is in photopic or mesopic mode, and we are mainly conscious of the foveal (cone) output of the eye to the brain. In emergency lighting, we are generally experiencing low illuminances to which the eye will adapt in time and our eyes enter the scotopic mode; then, foveal vision (which normally dominates visual perception) is subdued, and we tend to be conscious of a larger field of view because the dominance of the rod output improves our peripheral vision.

To illustrate how important it is to achieve a good standard of uniformity of illuminance in emergency lighting: consider a room of 10 m x 10 m, and assume that we have to find our way about in it by the use of a light source of 100 lumens. If our 100 lumens were derived from a handlamp and we directed its beam to the ground in front of us, it would make a bright patch of, say, 0.5 m diameter. The illuminance of the bright patch would be about 500 lux (sufficient by which to thread a small needle), but the remainder of the room would be in virtual total darkness, so it would be difficult to orientate oneself in the space and move about the room safely. However, if it were possible to distribute those 100 lumens uniformly over the whole room, it would produce an illuminance of 100/10 x 10 = 1 lux, an illuminance in which - once we were adapted to it - we could confidently and safely move about, and be able to orientate ourselves and avoid obstructions.

Safe movement at low lighting levels 19

3.1.3 Glare

Light which comes to the eye, directly or reflected from objects, which embarrasses vision and handicaps performance of the visual task, is termed glare. We discuss glare in these terms:

• discomfort glare, which does not affect the performance of the visual task (at least in the short term), but which tends to bring about an earlier onset of fatigue, and

• disability glare, which reduces what the subject can see, and - in an extreme case - so handicapping his vision that all he can see is the glare source.

In emergency lighting we are mainly concerned with the disability glare effect. This is what we suffer when, for example, we face the undipped headlights of an oncoming vehicle on an unlit road at night. But 12 hours later, in sunshine, a repetition of that situation would produce no visual disability, because the headlights would be seen against a background of far higher brightness. In the latter situation, the luminance of the headlights had not changed, but their luminosity as perceived by the subject had reduced considerably.

All lighting produces some degree of glare, i.e. there is no concept of zero glare. The degree of glare is subjective; it can be assessed or calculated (by reference to previous subjective assessments of glare experience) but cannot be measured.

Glare sensation is not directly related to the light output (lumens) of the glare source, nor to its intrinsic brightness (Cd/m2). Glare effect from a luminaire is affected by the brightness of surfaces against which it is seen. Background brightness is determined by the reflectances of surfaces and their incident illuminance; thus, emergency lighting installed in surroundings which have high reflectance (light colours) will be less glareful. A glare source close to the desired line of sight has a veiling or masking effect on that which we wish to see.

When the eye is subjected to glare, it cannot adjust itself instantly to the luminance conditions, though the iris contracts and the retina commences to adapt to the brightness presented to it (see Section 3.1.1). Thus, time is an important factor in glare sensation.

Reduction in glare improves visual performance, just as would an increase in illuminance. It should be an objective of lighting designers to limit glare in emergency lighting installations; for example, by


employing emergency lighting luminaires having cut-off in the zone above 70° from the downward vertical as required by BS 52664. This will enable the desired visual conditions to be achieved without wastefully high illuminances, thereby reducing capital cost, running cost and energy consumption.

3.1.4 Visual embarrassment

Emergency lighting systems designed on sound principles determined by the study of human vision sometimes do not enable subjects in an emergency to see as well as had been expected. In an emergency, many people do not see as well or as fast as would be expected from the theoretical considerations. Visual embarrassment is the term used to describe the condition where the subject does not see so well in an emergency as the test subjects did in passive tests, and the factors of its causation may include the following.

• Shock or fear

When the occupants of premises become aware that an emergency condition exists, e.g. by seeing smoke or fire, hearing the sound of an explosion, or hearing fire alarm sirens or bells, they are bound to feel some degree of excitement, fear or shock and, as a result, will undoubtedly experience the normal physiological effect of the rush of adrenalin which causes dilation of the pupils of their eyes.

Dilation of the pupils makes a subject especially susceptible to glare from any bright sources. Vision will be the worse if the subject is in a greater state of fear or shock - a fact that suggests that audible fire alarms in public places should not take the form of strident bells or sirens, but might be in the form of recorded announcements being played automatically over a public-address system. The messages can be couched in calm but authoritative tones which are calculated to inform and induce prompt action in leaving the premises, and also to reassure persons so as to reduce the risk of them panicking (see Section 3.4.2).

• Delayed adaptation

Before experiencing the shock stimulus of suddenly finding himself in a potentially dangerous situation in very little light, the subject would


have been adapted to the normal illuminance of his surroundings, which might be commonly 200 to 750 lux; in other words, his eyes would have been in photopic or mesopic mode. On being suddenly both frightened and plunged into moonlight levels of illuminance, his pupils will dilate and the process of adaptation to darker conditions (to scotopic vision) will commence - a process that must take something of the order of a minute to reach a substantial degree of adaptation. In those vital seconds, when his prompt action may be vital to save him from injury or death, the subject will suffer difficulty in focusing.

• Difficulty in focusing

Dilation of his pupils may make judgement of distance difficult for the first few seconds; then, as his retinas adapt to a very much lower field illuminance, he will find it difficult to focus at a distance because of the 'unseeing sentry syndrome' (i.e. the physiological state of 'normal night myopia'). Further, if the subject cannot see something clearly illuminated within a few metres of his position, this effect will be the worse because of the 'bland field effect'1. Any visual embarrassment the subject suffers due to difficulties in adaptation and focusing will be exacerbated by uncorrected defective vision or old age.

3.1.5 Colour in emergency lighting

In emergency lighting practice, there are two commonly held opinions: (a) that the colour of the illuminant used in emergency lighting installations is of little importance, for, it is held, the subject will be in the scotopic (dark-adapted) state in which there is little or no perception of colour, and (b) that it is sound practice to use green as the colour of exit signs, for green is associated with safety. After study of an important paper by S. M. Berman19, the author is no longer confident that either of those statements is sound.

• Colour of illuminant

Berman points out that, contrary to popular opinion, the cones play an important part in vision and adaptation at low illuminances, and in


particular in determining the pupil size. On his reasoning, an emergency lighting system using say, tungsten-filament lamps having a colour temperature around 3000 K, would enable the subjects to generate less acuity than another system which - while producing the same illuminance - used triphosphor fluorescent lamps of around 5000 K.

• Colour of signs

Berman shows that visual acuity is linked closely to colour, and demonstrates that the most effective composition for an illuminant -irrespective of the actual illuminance - would be as for sunlight and sky illumination. In other words, the lightmeter is not a sound guide to the acuity-generating effect of different colours of light. It follows that a luminous exit sign emitting light of a green colour would be less visible than one emitting only white light, and it might be more difficult for an escaper to see and focus on a green-emitting sign than a white-emitting one.

Notwithstanding the claims made for the traditional use of green exit signs, the author recommends that exit signs should emit only white light when illuminated, and preferably white light of good colour rendering. The use of white light will tend to cause the subject's pupils to contract, and therefore enable him to focus better, but his adaptation level may actually be enhanced. This effect is marked; it is believed, for example, that a daylight fluorescent lamp would be something like six times more efficacious than a low-pressure sodium lamp in terms of what is coming to be called 'pupil lumens'. It is appreciated that at the low illuminances used for emergency lighting the subjects will have hardly any perception of colour, but on the above reasoning the author recommends that emergency lighting systems should use good colour-rendering sources.

3.2 Identification of escape routes

3.2.1 Public behaviour in fires

The Fire Protection Association and the Loss Prevention Council (see Appendix B) publish excellent leaflets giving guidelines on how


to prevent fire in various kinds of premises. The Home Office have recently shown a series of short public information programmes on TV, and these have quite rightly dealt with fires in domestic dwellings (see Appendix C). None the less, it seems to the writer that there is need for a programme of public education in how to behave in a fire or other emergency, and particularly if the lighting fails, or if there is smoke present. It would be of great value if employees in all places of work, and members of the general public visiting public places (including shops and shopping precincts, hospitals, etc) could be induced (perhaps by a national programme of public information through the media) to follow some simple guidelines in event of fire.

It is appreciated that some situations demand essential things to be done as the subject makes his or her escape; for example, in a shop or supermarket, the till operators are trained to close the till, and then to lead members of the public to the exits (see Section 1.3); but the general public should be advised:

/ / the fire alarm sounds, or there is some emergency, do not delay, but immediately make your way calmly towards an exit and leave the premises.

Conditions at the instant of an alarm may be complicated by a degree of visual embarrassment (see Section 3.1) which may cause them to see little or nothing during the first few seconds after the commencement of an emergency coupled with loss of the general lighting - even if lighting to BS 5266 is provided and the area is not densely smokefilled. The guideline to occupants should be:

If the lights go out and you are in conditions of very little light, pause for a few seconds to let your eyes adapt to the low light level, and then make your way calmly towards an exit and leave the premises.

It is not at all uncommon for persons to panic on seeing or smelling even a little smoke. There have been people perishing in fires because they have rushed to the windows screaming for help, when they could have gone quietly down the stairs and escaped without harm. The guideline could be along the lines of:

/ / the place where you are fills with smoke, get down on the floor beneath the smoke, where it is cooler and where you will be able to breathe, and then crawl on hands and knees to an exit.


As discussed in Section 3.3, escape by crawling beneath the smoke will be facilitated by the provision of a suitable low-mounted luminous way-guidance system (see Section 5.4).

3.2.2 The need for new practices

Lighting specified to BS 5266 has been fitted in thousands of installations since that Standard was first published in July 1975. Such systems work excellently if the emergency which necessitates the evacuation is nothing more serious that a simple failure of the normal lighting, so that all that the occupants have to do is to make their way carefully to an exit and leave the building. Persons needing to escape may be unfamiliar with the environment they happen to be in when the general lighting fails or when dense smoke or a dust cloud quickly obstructs their vision. There is an urgent need for the general adoption of improved systems for guiding people along escape routes.

Persons in a fire are more likely to die from asphyxiation by inhaling smoke and poisonous fumes given off by burning substances than from actually being burnt. Modern buildings contain a great deal of flammable organic and plastics materials, and seem overall to be more flammable than buildings erected and furnished in earlier decades. Much has been done by the British Standards Institution and organizations such as the Furniture Research Association to promote the use of materials and substances which are non-flammable, less flammable, self-extinguishing, or less likely to produce toxic fumes and dense smoke if ignited.

Many occupiers, as well as many suppliers of emergency lighting equipment and practitioners in building services engineering, now believe that methods of lighting to enable persons to escape safely from a darkened building in any emergency - and especially in the presence of smoke - should include a system of low-mounted as well as high-mounted luminous signs (see Sections 3.3 and 5.2), plus floor-recessed or skirting-board mounted luminous strips (see Section 5.4), and perhaps luminous tactile guidance devices (see Sections 3.6 and 5.4). It is becoming increasingly the opinion of experts that such way-guidance systems should be provided in addition to - or perhaps instead of - the high-mounted, low-illuminance emergency lighting systems now employed. Another growing opinion in the technical field is that the logical place to locate luminaires to illuminate an


escape corridor is no higher than 600 mm, and preferably only 300mm above the floor (see Section 4.3).

It is the author's opinion that the present practice of providing emergency lighting to BS 5266 Part l4 fails to achieve the function of enabling escape in smoke. He has held this view since the standard was published in 1975; he has said so often in his press articles and in his public lectures. In an article in the Electrical Times in 198015 in which he recounted his personal experience of being in a real fire, he wrote: 'During the fire, one could breathe and see only in a shallow stratum extending about 300 mm above the floor. Yet I am told that low-mounted escape-lane lighting is frowned on by some who claim to be expert in these matters.'

Happily, enlightenment seems to be dawning. In February 1991, a panel of very experienced engineers visited the Building Research Establishment, Watford, to witness some tests of emergency lighting to BS 5266. The panel comprised: Mr T C Boxer (JSB), Mr C Watts (Menvier, and chairman of BS 5266 Committee LGL/24), Dr V Crisp (BRE), Dr G Webber (BRE), Mr L Bedocs (Thorn/CIBSE) and Mr M Kormanic (LIF/ICEL). The panel witnessed test demonstrations of lighting giving 0.2 lux on the centreline of escape routes (per BS 5266), as well as demonstrations of systems of way-guidance including titrium glow strips, photoluminescent strips, electrolu-minescent strips, filament-lamp strips, and conventional and LED exit signs. The systems were then reviewed a second time as before but with evenly distributed dense smoke present. It was found that the overhead lighting was useless, and that increasing its brightness actually made vision more difficult. Of the exit signs examined, all except the LED version could not be seen beyond about two paces, and the LED one could not be seen beyond three paces. They found that the only way to move safely in the smoke was on hands and knees, and that the electroluminescent and filament-lamp strips gave good guidance. Their conclusion was -

'...it was generally realized that in smoke conditions conventional emergency lighting and Exit signs were virtually useless.'16

In other words, it is admitted that the effects of smoke had previously not been appreciated to the full by prominent members of the emergency lighting profession.

It is good to be able to report that Mr Watts, as chairman of BSI Committee LGL/24, has taken steps towards the appropriate action


with the view to creating a new or revised British Standard for emergency lighting in smokefilled premises. Since then he and his BSI CEN committees have worked hard producing some new recommendations. However, as far as the author has been able to ascertain, a year later (February 1992) no public action had been taken, and BSI state that they have no information about a proposed revision of BS 5266 Part l4. It had been proposed that there would be a further visit to BRE by members of a European Standardization Committee to see the tests and to consider the findings, but there has been no announcement of this. It is hoped that the publication of the present book will influence the manufacturers of emergency lighting, CIBSE, ICEL, BSI Committee LGL/24 and those responsible for European Standardization, and will encourage them to the following objectives:

• to modify and update the standards of emergency lighting to include the use of low-mounted luminous way-guidance devices (see Section 5.4) and low-mounted floor-flood luminaires (see Section 4.3);

• to think again about the design and purpose of high-mounted luminous exit signs, and develop and encourage the use of signs that are easier to see and recognize from a distance under all lighting conditions in smokefree situations (see Section 5.2);

• to accept that only low-mounted luminous exit signs and luminous devices can give the necessary guidance in smokefilled conditions (see Section 5.2); and

• to think again about the use of worded exit signs and 'running man' pictograms, and give proper consideration to the use of 'broad arrow' direction symbols for signing exits (see Section 5.2).

Until the EC Standards - and the laws of the EC countries - are changed, it would probably not be legal for occupiers to install low level way-guidance systems as the only means of illuminating escape routes, and if they did this it is unlikely that any inspecting officer would issue a Fire Certificate for the building concerned. However, there is nothing to prevent occupiers installing low-level way-guidance systems (see Section 5.4), low-mounted exit signs (see Section 5.2), and low-mounted floor-flood lighting (see Section 4.3) now, provided such equipment is installed in addition to conventional emergency lighting to BS 5266 Part l4. It is the author's belief that this action would save many lives.


3.3 Escape guidance in smokef illed areas - the need for research

3.3.1 The problem

In all branches of the lighting art, lighting systems and luminaires are devised by engineers to provide solutions to the problems that they envisage. Thus, BS 5266 offers a practical solution as to the problem of providing just enough light to enable persons to escape from premises when the normal lighting fails. But, when the space is filled with smoke, we have a quite different problem.

When fire occurs, dense hot smoke may fill a room or a corridor very rapidly (e.g. within 30 or 60 seconds of the commencement of the emergency), perhaps leaving a clear zone of no more than 300mm above the floor. Similarly, when a bomb explodes, a dust cloud instantly fills the space, and this may be dense enough to hinder escape. In such conditions, conventional exit signs mounted 2 to 2.5 m above the floor will be invisible. Conventional overhead emergency lighting will not penetrate the smoke, so the floor will be in darkness. Indeed, even the normal lighting, which in ordinary conditions would produce an illuminance of some hundreds of lux at floor level, under even slight conditions of smoke or dust in the atmosphere may not be able to penetrate to the floor and would be useless as an aid to escape.

If the occupants do not escape from the premises quickly, the conditions may worsen. For example, air turbulence may cause dispersal of the smoke so that it occupies the formerly clear strata near the floor. In a short time the smoke will cool and may descend, filling the volume of the escape route near the floor.

Persons needing to escape may be unfamiliar with their surroundings when the general lighting fails or when dense smoke quickly obscures it, and can easily become confused and frightened. For example, a shopper who enters a departmental store may follow the displayed instructions and use a lift or escalator to go to her chosen destination department on an upper floor. If shortly afterwards there is an emergency, retracing her steps will not necessarily enable her to find a safe route out of the building.

If persons who find themselves in smoke have the good sense to get down quickly to the floor, they may be able to breathe and move towards an exit - but only if they can find the right direction. There is


a growing body of experts and non-experts who express grave doubts about the practice of mounting emergency lighting units only at conventional positions, i.e. at 2 m or higher, per BS 52664 (see Section 3.2).

The usual objection to proposals to use low-mounted emergency lighting luminaires or low-mounted way-guidance systems is that they would be obscured by the bodies of other escapees; but this may be an unsound argument (see Section 3.4).

In research and development, new proposals for lighting systems are generally tested by engineers. As far as can be ascertained, all the assessments of effectiveness and visibility relating to emergency lighting and escape systems so far carried out in the UK have been made by small panels of 'experts', mainly drawn from the lighting industry. It is not intended to malign such persons, but it has to be recognized that companies have a vested interest in selling products for which they are already tooled-up, and therefore may resist change when new ideas come along.

It could be very revealing if new and proposed systems of escape lighting were tested by some ordinary members of the public under conditions of realistically simulated emergency, and the results assessed by impartial judges. The truth of the matter is that little is known about how a group of people would behave in a real smoky fire if they were provided with an effective low-mounted way-guidance system, and it is time that this was properly researched. In order to learn how ordinary people react to various types of emergency lighting and escape guidance systems, it could be instructive to conduct experiments with substantial numbers of persons (see Section 3.3.2).

3.3.2 A proposal for practical testing

A possible outline format for such experiments might be as follows:

The test environment

• The test area should be adequate in size to accommodate the number of persons in the test, and should not admit daylight. The main area should have several exits, and these should lead to


escape corridors of substantial length. The escape corridors should include hazard features such as ramps, right-angle turns, stairs and unexpected obstructions.

• The test area should be equipped to be lit at several general-lighting levels - say, 200, 500 and 750 lux - the illuminances that are commonly used in interiors.

• In addition to general lighting and emergency lighting to BS 5266, the test area and escape corridors should be equipped with the types of emergency lighting equipment it is desired to test, including floor-recessed and wall-mounted luminous way-guidance systems (see Section 5.4) and low-mounted floor-floods (see Section 4.3).

• Means should be provided for introducing quantities of hot or cold smoke into the test area and escape corridors. The smoke should be optically-dense but non-toxic.

• Means should be provided for observing subjects during tests, including audio and video recording, and means for timing their progress, without them being aware that this is happening.

The test subjects

• The subjects participating in the tests should be persons having no special knowledge of emergency lighting. They will preferably be a mixture of all ages, from children to elderly. They should be chosen to be typical of a random group of the public, including parents with small children or prams, and persons carrying bags of shopping.

• The number of persons in a test should be as great as can be arranged - at least 100 persons would be a reasonable minimum number to simulate conditions in such places as shops, shopping malls, stadia etc.

• The subjects should have agreed to participate in a test, but should not be told what to expect. They should be assured that they will not be placed in danger.

• Unknown to the test subjects, one or more experimenters would be inconspicuously included in the group. They could thus ensure that no test subject came to harm, and could have means of terminating the test in a real emergency (e.g. communicating by a pocket-size bleeper).


The test procedures

• The subjects would be asked to enter the test area. When they enter the room, there should be ordinary general lighting to a known illuminance. The subjects should remain in the test room in that illuminance for a period of say, 10 minutes before the test begins, so that their eyes would be well light-adapted, just as they would be in real life immediately before a lighting failure.

• After the test subjects have been in the test area long enough to become adapted to the ambient general lighting, the general lighting would be extinguished without warning. A recorded announcement would ask the test subjects to move calmly out of the test area along the escape routes that are defined for them by the signs, way-guiding luminous devices or low-mounted floor-floods which are under test.

• During the test, accurate records should be kept of all events. For example, if the test area had two exit doors with different signing, a record should be kept of how many used each door. The time that subjects take to traverse the distance to the 'designated place of safety' should be recorded.

• Each test should be repeated with a new population of test subjects but with the presence of smoke.

3.3.3 Summary and objectives

The term 'smokefilled' includes not only the condition where hot smoke leaves a fairly clear strata of air close to the floor, but also that where cold smoke sinks to a low level; or where because of turbulence or great quantity of smoke, the volume of the escape corridor is completely full of smoke. If the escape strategies discussed elsewhere in this book are achieved, in a real fire it would be the objective for occupants to have got clear of the dangerous areas before such smoke conditions had developed.

The tests should take account of the vital matter of timing. If a real fire is detected early, if the alarm is given promptly, and if the occupants immediately commence evacuation, they have increased chance of escaping safely. It would be an objective that they would be clear of the danger area before the smoke cooled and filled the lower volume of the escape corridors.


It must be stated that at present there is no firm basis on which to predict which type of way-guidance system (see Section 5.4) or which type of low-mounted floor-floods (see Section 4.3) will give the best results under all conditions.

A series of tests as described, using substantial numbers of test subjects, and subjecting them to different initial lighting conditions, different emergency lighting systems, and different way-guidance systems, would enable theories to be tested, and the best systems and products to be developed or improved.

It is hoped that the trade organizations, and the professional organizations concerned with lighting - as well as those concerned with public safety - will participate and share in this work - and perhaps in its cost. As the lighting industry has no research centre of its own, perhaps a research programme as outlined here could be mounted at the Building Research Establishment or at a university. Such a programme would be very much in the public interest, and - in view of the human suffering and loss of life that might be prevented -would well deserve Government funding or a grant from the European Community.

The results of such research would be not just of academic interest, but clearly would influence future standards of fire safety and emergency lighting systems. It is quite likely that the results of such research would necessitate a fundamental rethink of the whole subject of lighting to aid escape from premises. This could only be of long-term value to the lighting industry, as well as significantly enhancing the safety of the millions of persons who live and work in all kinds of buildings.

3.3.4 A recent research

Since the foregoing was written, a paper describing a programme of research carried out by Aizlewood and Webber at the Building Research Establishment has been published41. The paper describes their practical experiments involving 24 test subjects who traversed a test route under various conditions of emergency lighting and 'wayfinding' (way-guidance). The authors are to be congratulated on this eminently practical research which studied the speed of movement of subjects, recorded their opinions, and assessed their ability to negotiate the test route with the presence of various minor


obstacles. The general conclusion was that the performance of users escaping by the aid of way-guidance systems could be as good as or better than their performance under conventional overhead emergency lighting.

The systems of way-guidance used in the tests included luminous way-guidance track and markings illuminated by photoluminescent material, by electroluminescent material, and by subminiature filament lamps, but did not include tests of tracks illuminated by LEDs. Subjects were timed, observed covertly, and were questioned on what they saw, and their opinions of the various lighting conditions were noted. Each subject traversed the test route four times.

While welcoming this paper as evidence of serious progressive thinking along the lines which form much of the substance of the present book, and acknowledging that it is the intention of BRE to carry out further similar tests under smoke conditions, the following adverse comments on the test programme as described must be made:

• The test subjects went through the test route singly, and were not subjected to the problems of crowding that occur when a group of people are trying to escape from danger. They therefore did not suffer the physical and visual obstruction of a mass of other bodies, nor the stress which may arise from the aggressiveness or competition of other escapers in a real danger situation.

• Valuable though the results are, the tests were performed in clear air conditions, and therefore can tell us little about how persons would behave in a similar environmental situation when smoke is present.

• Because the test subjects each went through the test route four times, there was doubtless a measure of learning which simplified their task. Therefore the tests tell us nothing about how a crowd of strangers would behave in the same conditions if they were unfamiliar with the test route.

Not only did the experimenters conclude that a low-mounted way-guidance system could be just as effective - or better - than a conventional system of overhead emergency lighting in enabling persons to escape from a building in clear air conditions, but they stated that way-guidance systems deserve serious consideration by


the industry, designers and specifiers. They said they see a need for new European and British Standards to deal with the subject of way-guidance as a method of emergency lighting for smokefree conditions.

It is most encouraging to learn that BRE intends in the future to study escape routes in smoky conditions, but the author believes that tests which involve only sending individual test subjects through the test route will still not answer the question: What are the best lighting conditions to enable a crowd of frightened people to get out of a dark - possibly smokefilled - building, quickly and safely, when they are not familiar with the route?

3.4 Escape guidance in densely occupied areas

3.4.1 Introduction

This Section discusses the effectiveness of emergency lighting methods, the visibility of exit route signs, and the effectiveness of illumination and way-guidance along escape corridors. Twelve different cases are considered. Referring to Table 3.1:

Cases 1, 2, 3 and 4 are where the premises are provided with emergency lighting and exit signs to BS 5266. Cases 5, 6, 7 and 8 are where the premises are provided both with emergency lighting and exit signs to BS 5266 and also with a low-mounted way-guidance system. Cases 9, 10, 11 and 12 are where the premises are provided only with a low-mounted way-guidance system and no conventional emergency lighting. Cases 1, 2, 5, 6, 9 and 10 assume that there is an emergency which requires the evacuation of the premises, but that the normal lighting is operative. Cases 3, 4, 7, 8, 11 and 12 assume that the normal lighting has failed, whether or not there is any other emergency condition requiring evacuation of the premises. The conditions in the twelve cases discussed are summarized in Table 3.1.


Table 3.1 A comparison of conventional emergency lighting, way-guidance systems, and combinations of both, in smokefilled and smokefree conditions when the escape routes are densely crowded

Case No.

1 2 3 4

5 6 7 8

9 10 11 12

Condition of the

normal lighting (note A)

On On

Failed Failed

On On

Failed Failed

On On

Failed Failed

Is BS 5266 emergency

lighting installed? (note B)

Yes Yes Yes Yes

Yes Yes Yes Yes

No No No No

Is low-mounted way-guidance

installed? (note C)

No No No No

Yes Yes Yes Yes

Yes Yes Yes Yes

Is smoke present? (note D)

No Yes No Yes

No Yes No Yes

No Yes No Yes

Safety rating

(note E)

5 1 3 1

5 4 4 3

5 4 4 3

Notes to Table 3.1 A - The normal lighting is assumed to provide an illuminance of 200/500 lux

at floor level in smokefree conditions. B - The emergency lighting is assumed to be a conventional system to BS

5266, with luminous exit signs over doorways at 2 m above floor. In cases 9,10,11 and 12, it is assumed that no overhead emergency lighting is provided, but that luminous exit signs are fitted over doorways at 2 m above floor.

C - The way-guidance system is assumed to be a skirting-board mounted or floor-recessed luminous way-guidance strip system of the types discussed in Section 5.4, plus low-mounted luminous exit signs.

D - The presence of smoke is assumed to be hot smoke such that it obscures the upper volume of the space and is dense enough to make a standard luminous exit sign (mounted at 2 m above floor) invisible at 2 to 3 m distance.

E - In attributing an arbitrary safety rating to each of the twelve cases, the author has taken into account the factors set out in Section 3.4.2. Referring to the grade of safety likely to be achieved by the various systems under conditions of 'lighting normal', 'lighting failed', 'smokefree' and 'smokefilled' as shown in the table, the safety ratings are scaled as 5 = Excellent, 4 = Superior, 3 = Satisfactory, 2 = Moderate, and 1 = Poor.


3.4.2 Factors affecting the arbitrary safety ratings allotted to systems listed in Table 3.1

In allotting the arbitrary safety factors to the twelve cases listed in Table 3.1, the author considered the following:

• Apparent brightness of exit signs

In the presence of the normal lighting, the apparent brightness of BS 5266 internally-illuminated exit signs will be relatively low, and the signs may not be readily visible from a distance. This 'swamping effect" will depend on the level of general lighting illuminance, the intensity of light from the general lighting luminaires directed towards the exit sign and its background, and the reflection factors of the sign and its background. In a space having a general lighting system comprising diffusing luminaires or uplighters, the upper wall brightness may be high, and the exit sign may not be at all noticeable as its brightness will be of the same order as that of its background. However, under conditions of failure of the general lighting, but with the correct operation of emergency lighting to BS 5266, the exit signs will appear to be brighter than when viewed under high ambient luminance conditions. (Some proposals for the provision of more easily recognized luminous exit symbols are given in Section 5.2).

• Illuminance on the floor

A general lighting illuminance of, say, 200 to 500 lux on the floor in an empty room may reduce to a small percentage of this illuminance on the floor when the room is densely occupied. An emergency lighting illuminance of, say, 0.2 to 5 lux on the floor in an empty room may reduce to an almost immeasurably small value when the room is densely occupied. When, because of obstruction by smoke, or obstruction by escapees' bodies, there is insufficient light at each escapee's feet to enable hazards, change of level or steps to be seen and negotiated, tripping and falling may occur, and persons may be injured by being crushed or trodden underfoot.

• Panic

Panic may occur in any dense crowd, leading to injuries when the persons at the rear push impatiently - being unaware of why the


people at the front are not moving along. Darkness or poor lighting conditions may exacerbate such a situation.

• Finding the escape route

In a dense crowd, in the absence of smoke, persons may be able to see the distant high-mounted exit signs; but they may not be able to see them at a distance of greater than 2 to 3 m in the presence of smoke. A person in a dense crowd whose view is obstructed by other persons may lose his sense of direction, especially if he is unable to see an exit sign ahead. It is important to note that, in a dense crowd, children and persons of short stature cannot see ahead, and may be unable to see distant exit signs even in smokefree conditions. Being able to see the ceiling (if the normal lighting or the overhead emergency lighting is working) may help to offset this effect, which leads to the possibility of placing escape route direction signs on ceilings (though, of course, they would be obscured in smoky conditions). In both smokefree and smokefilled conditions, orienta-tion may be aided by the use of luminous way-guidance devices recessed in the floor or at skirting-board height.

• Luminance of low-mounted way-guidance systems

As described in Section 5.4, a system of floor-recessed or skirting-board-mounted luminous way-guidance devices (the compo-nents of which may have a brightness of say, 5 to 40 cd/m2) will not appear to be very bright when seen under normal empty-room lighting conditions (an illuminance of say, 200 to 500 lux on the floor). Low-mounted way-guidance devices will appear to be much brighter if the ambient light flowing towards the floor is limited (i.e. under emergency lighting conditions), and brighter still when light flowing towards the floor from overhead normal lighting or emergency lighting is largely obstructed by the bodies of escapees. It is believed that, even under dense crowd conditions, a suitable low-mounted way-guidance system would assist escapees to navigate obstructions and changes in floor level; it would assist them to orient themselves and to move towards an exit, on foot or crawling on hands and knees.


• Obstruction of low-mounted way-guidance systems by other persons

It is a common objection to the use of low-mounted luminous way-guidance systems for emergency escape that they may be concealed from view by the presence of other people, and that the brightness of such devices would be insufficient to provide the necessary guidance and reassurance to frightened persons trying to escape in an emergency. The author believes this not to be so, and proposes that these factors should be the subject of practical tests (see Section 3.3).

3.4.3 Some conjectures

It would seem from the considerations in Sections 3.4.1 and 3.4.2 that there is a case for adopting the use of low-mounted way-guidance systems to aid the movement of persons along escape routes. It is appreciated that low-mounted systems might be obstructed by furniture, by items placed in or near the escape corridors - for example, in shops they might be partially obscured by temporary displays; none the less, they have the potential to provide greater safety in crowded conditions, and in the presence of smoke.

If, after thorough testing (see Section 3.3) it was shown that way-guidance was more likely to get people safely out of danger than any other system (even in conditions of smoke or when the escape corridor is packed with people), it might be argued that there is no need for an overhead system of emergency lighting to BS 5266 (which, although not specifically cited in legislation, is at present a requirement in business premises in the UK) - but the validity of this statement has not yet been tested.

With any system of low-mounted way-guidance, it would always be an essential requirement to provide clearly visible luminous exit signs at high level (2 to 2.5 m above floor) for these, being normally visible from 20 to 50 m away, give essential guidance and may enable rapid evacuation of the premises before they become smokefilled; but the author doubts whether overhead emergency lighting will remain mandatory beyond the next few years. It seems likely that future developments will lead to the approval of emergency lighting systems comprising conventional luminous high-mounted exit/direction signs


plus low-mounted way-guidance, and that, in time, the provision of conventional overhead emergency lighting will become optional. It would only take one or two reports of people escaping safely through smoke with the aid of low-mounted way-guidance systems for the insurance companies to start stipulating their use irrespective of the provision of overhead emergency lighting.

3.5 Escape guidance in outdoor areas

3.5.1 Legal requirements

UK and EC legislation (see Section 2.2) imposes duties on occupiers of premises which go far beyond the basic Common Law duty to provide for the reasonable safety of employees and other persons who enter their premises (see Section 2.1). The word 'premises' in legislation and in Common Law does not mean only the buildings; it includes also all exterior spaces. In other words, the occupier has a clear legal duty to provide 'sufficient and suitable' lighting over the whole of his premises, including all outdoor areas accessible to the occupants.

An outdoor industrial area may be a dangerous place; it may for example, contain chemical storage vats or gas cylinders which could cause injury to persons should there be a fire or an accident with a vehicle or a crane. In such circumstances, persons in the vicinity will need to be able to see so they can escape to a place of safety, even under mains-failure conditions at night. Only when lighting is provided that satisfies this need will the occupier's duty to provide for the reasonable safety of persons be performed.

3.5.2 Current practices

Outdoor lighting installations at industrial premises in the UK rarely incorporate proper facilities for personnel safety in the event of mains failure. In general, industry does not provide lighting levels out of doors that meet the recommendations of the CIBSE Code8 for similar tasks performed indoors, nor the requirements of BS 52664 or Lighting Guide LG0623 for external emergency lighting; indeed, outdoor emergency lighting to facilitate escape is rarely provided and, even when it is provided, it may not be fully effective.


It is clearly a matter of great importance to provide sufficient illuminance under mains-failure conditions to enable a person to pick his way safely across an industrial yard cluttered with potentially hazardous obstructions on a dark night and reach a place of safety.

3.5.3 Possible future practices

The recommendations of BS 52664 have little relevance to the needs for providing lighting for escape in outdoor areas. For example, if a minimum centreline illuminance of emergency lighting level of 0.2 lux is needed to enable a person to find his way along a well defined corridor with a level floor, it is apparent that he would need a rather higher illuminance in order to be able to descend safely in darkness down a series of ladders from a partly constructed building when the lighting has failed.

It has long been the opinion of the author that there is need for a new standard for outdoor emergency lighting, especially for construction sites, in chemical plants, and in other hazardous outdoor areas. It is hoped that the law will be amended to make it clear that occupiers have a duty to provide emergency lighting out of doors. It is understood that suitable standards for exterior emergency lighting will be imposed soon by EC legislation; in the absence of official guidelines, the proposals given in Section 3.5.4 may be followed.

3.5.4 Emergency lighting illuminances for outdoor applications

Occupiers must satisfy the requirements of local legislation and the lighting codes of the country in which a lighting installation is located, as well as contractual requirements. In general, the lighting requirements for minimum standards of safety and health are greatly exceeded by the levels of lighting commonly employed for ordinary efficient operation of plant and premises. There is no general agreement as to the levels of illuminance required for outdoor security lighting, for outdoor emergency lighting, nor for many types of outdoor work, and anomalies exist between recommendations for the same function when performed indoors or outdoors.

The determination of illuminances for emergency lighting for outdoor workplaces is not a subject upon which lighting experts are


yet generally agreed. The author's proposals are set out in Table 3.2 (see Section 10.1) and are based upon the following two principles: • that the level of the emergency illuminance (lux) should take

account of the nature of the escape route, and particularly in respect of possible hazards to persons traversing that route; and

• that the emergency illuminance (lux) should take account of the illuminance level that was present immediately before the failure of the normal lighting.

The minimum measured illuminance (MMI) values given in Table 3.2 are used for checking the installation, and are values measured on the ground below which the illuminance at any point should not be allowed to fall. They are values which should be sought for and checked regularly with a lightmeter, and the appropriate actions taken if the MMI level is not found at any point in the lighted space.

3.5.5 Pilot lighting

It is recognized that it would be impracticable and extremely costly to try to apply BS 52664 standards of emergency lighting to the whole of very large outdoor industrial areas. However, emergency lighting at many such locations might be achieved by installing a system of pilot lighting (sometimes called 'beacon lighting'), i.e. a system of strategically placed luminaires or luminous direction signs which would act as markers under conditions of failure of the normal lighting.

When the normal lighting is not operating, pilot lighting will enable a person to safely traverse a series of clearly marked straight paths through the site for the purposes of fire patrol or security patrol, or enable him to make his way to an exit or designated place of safety. If such pilot lighting systems were supplied from an uninterruptible electrical supply, a considerable increase in safety over present practices would be obtained. In hazardous areas, the pilot lighting luminaires would need to be of suitable protected design.

3.5.6 Escape route marking

For marking escape routes and denoting exits in outdoor working environments (and especially in hazardous ones) the use of


intrinsically safe phosphorescent markings and exit signs is known (see Section 5.3), and this practice has much to recommend it. Particularly in places where the public may be present, the use of luminous way-marking strips along exit routes and to delineate paths and stairways, luminous handrails or balustrades for guidance along the escape path in darkness and smoke should be considered (see Section 3.3). The use of internally-illuminated bollards with luminous directional signs to aid pedestrian movement should also be considered; such bollards can be constructed as self-contained emergency lighting units (see Section 7.2.4).

3.5.7 Personal lights

In some dangerous locations it is good practice for operatives to carry personal lights with them - just as miners invariably wear their cap-lamps; but in many industrial locations it is not practicable for persons to carry with them a personal light, i.e. a torch or handlamp, such equipment being easily lost or broken, and liable to be stolen; it is also difficult to ensure that the batteries are kept in a good state of charge. However, it is perfectly feasible for persons entering or working in such areas routinely to carry with them one or two chemical light sticks (see Section 7.5.4).

3.6 Locations and groups of users requiring special features of emergency lighting

This Section discusses some locations and groups of users (taken in random order) which may require special features of emergency lighting.

3.6.1 Hospitals

The guidelines given in Hospital Technical Memorandum No. 11 'Emergency electrical services'33 may, at the discretion of the enforcing authority, supplement or replace the recommendations of BS 52664.


It is now common practice in the UK for the lighting in surgical operating suites and intensive care wards to be provided with uninterruptible supplies (see Section 6.3), but it is less clear what arrangements are made in other parts of hospital premises, though stairs and corridors are normally fitted with escape lighting.

In wards, the problem is that during a failure of normal lighting (without any other emergency condition requiring evacuation), patients must still be supervised and essential procedures carried out. Some wards have low-mounted wall-recessed nightlight luminaires, and these might be readily converted to provide emergency escape lighting, perhaps merely by being fed from a maintained emergency power circuit.

In some modern hospitals, in addition to the bed-head light (provided for the use of the patient), there is also a 'watchlight', this being a luminaire containing a low-wattage lamp; this is used by the nurse to see the patient's face at night without unnecessarily waking him up. It would seem to be a good practice to place watchlights on a maintained electrical supply.

During a power failure, medical and surgical procedures in the wards may be carried out using portable self-powered lighting; for example, trolley-mounted luminaires powered by standby batteries carried in the trolleys.

Evacuation of wards on upper floors almost invariably requires that beds, stretcher-trolleys or wheelchairs must be taken down in lifts. Although it is normal practice not to operate lifts during a power failure or emergency, in such cases special standby power supplies must be provided for the lifts, both for lighting and for motive power.

3.6.2 Persons in wheelchairs

Many public buildings are now provided with wheelchair access, and it is common for wheelchairs users to ascend to upper floors by lift (see Section 3.6.1). If a system of ramps (of such design that wheelchairs may use them safely) is provided, these should be provided with a generous level of emergency lighting, and very clear marking of the edges of the escape corridors (see Section 3.6.13). A code of practice for means of escape for disabled people is given in Part 8 of BS 558831.


3.6.3 Persons with visual handicap

Some persons registered as blind have some small measure of vision which is insufficient for normal seeing and mobility, but which might enable them to follow a brightly luminous low-mounted way-guidance system (see Section 5.4) as can many partially-sighted persons. In consultation with organizations who can provide expert advice in this field, it may be possible to provide other facilities to persons with a visual handicap to escape from premises in an emergency, such as:

• low-mounted luminous guidance signs could be provided along escape corridors (see Section 5.4), perhaps at luminances far higher than would be employed in other premises;

• in addition to announcements being made over public address systems, repeater loudspeakers might be provided to give guidance and reassurance along escape routes;

• the conformation of the kerbs, or the surface of escape corridor floors, could be of such nature that will enable visually handicapped persons to follow the escape route (as is already practised to enable visually handicapped persons to move about in training establishments and in certain gardens open to the public);

• in appropriate situations, illuminated handrails to aid escape should be employed in places in which visually handicapped persons may be present (see Section 5.4.5).

Such features would, of course, be additional to the normal features of an escape corridor for use by sighted persons.

3.6.4 Schools

It is common practice to teach children the 'Green Cross Code' relating to how to cross a road safely; this has doubtless saved many children from injury or death. It is suggested that emergency lighting and exit signs and symbols, and the luminous way-guidance marking of escape routes should also be the subject of education to children and young persons. The emergency lighting and escape signing in the schools could be used as teaching aids. It is desirable that, from an early age, children should be able to recognize the signs for an escape route, and know how to behave during a failure of lighting or in any other emergency - including fire and the presence of smoke.


3.6.5 Public transport

Some railway and airport premises present considerable risk to persons on crowded concourses should there be a failure of the normal lighting. Failure of lighting can lead to danger to persons on railway platforms in the dark hours, and at all times on underground stations. Following the King's Cross disaster, public authorities and the transport industry expressed considerable interest in the means of guiding large numbers of persons to safety in dark and smoky conditions. There are systems of luminous handrails and luminous balustrades available which give guidance to persons for escape (see Section 5.4).

3.6.6 Large retail stores

In the case of fire occurring in large retail premises, there is an essential need to evacuate large numbers of people (including elderly persons, small children and babies in prams) quickly before there is a build-up of smoke. Simple failure of the normal lighting can create considerable difficulty, as many persons on the premises may be unfamiliar with the store layout and may not know which way to go to reach an exit. They may become confused and frightened, as the only way out of the store that they are familiar with is through the checkouts.

In the case of stores on several floors, customers who are unfamiliar with the store layout may be in difficulties when the alarm sounds or the lights fail. They may have come to their present positions on an upper floor by lift or escalator, and will have to find their way down again by a different route. Clear informational and emergency exit signs have an educational purpose in training customers into a knowledge of the store layout for their own safety (Figures 3.1a, 3.1b and 3.2).

Public address systems are used in stores as a promotional aid, and also for staff messages. In the crowded conditions such as are common in large stores during sale time, recorded announcements broadcast over the public address system will inform customers and staff of any emergency, but without generating the fear and possible panic that may follow the sounding of strident bells and alarm sounders. The wording of announcements may be tailored to the


Figure 3.1a Externally illuminated exit sign in a retail store, (see Section 3.6.6)

needs of persons in each part of the store, and can be varied during the course of evacuating the premises to take account of some escape routes being obstructed or smokefilled (see Section 8.4).

For emergency lighting in large supermarkets and large retail stores, conventional emergency lighting luminaires may have to be positioned at 4 to 6 m centres on ceilings that may already be cluttered with the normal lighting and other services. Because of the presence of floor obstructions (which may change in form and position according to marketing needs), a preferred method may be


Figure 3.1 b Externally illuminated exit sign in a retail store, (see Section 3.6.6)

to use the normal overhead lighting for emergency use; this is conveniently done by placing some of the fluorescent lamps on maintained circuits. This method uses lamps of considerably greater lumen output than the lamps commonly used in emergency lighting; if the selected lamps are correctly spaced to ensure even distribution, it will result in emergency lighting at illuminances considerably higher than in conventional schemes. To limit the power consumption, the selected lamps can be operated at lower power when in emergency mode. To avoid problems with overheating, batteries and chargers, etc may be placed in separate local compartments, each serving one

Safe movement at low l ighting levels 47

Figure 3.2 Exit route signing designed to be visible from a distance in a large open-plan departmental store, (see Section 3.6.6)

or a group of luminaires. Alternatively, the lamps selected for emergency duty may be connected to a central battery or standby generator system (see Chapter 6).

A code of practice for fire precautions in the design, construction and use of shops is given in Part 2 of BS 558831.

3.6.7 Hotels and residential premises

In the management of fires and other emergencies relating to all kinds of residential premises, it must be noted that escapers may have nowhere to go when turned out from the danger area (see Section 3.7). It is essential to have wardens or police present as soon as possible to protect property.

3.6.8 Passenger lifts (elevators)

It is normal good practice to locate emergency lighting luminaires within lift cars and in lift lobbies. An experienced fire officer has


advised that it is very helpful to the brigades if an emergency lighting luminaire is also located on the roof of each lift car, as this facilitates rescue of trapped persons in a power failure.

3.6.9 Stairs and escalators

When lighting is restricted, all stairways are somewhat hazardous. It is good emergency lighting practice to locate a luminaire within 2 m of any hazard, and this should include the head and foot of any stair flight including escalators. It is likely that future standards will call for a minimum illuminance of 1 lux on all treads of stairways forming part of escape routes, and this illuminance - or better - should be adopted for systems being designed now (see Section 10.1).

When an escalator stops because of power failure, its motion arrests quite sharply, and there may be accidents due to persons falling. When an escalator is stationary, it may be used as a means of escape, but people may be confused by the top and bottom steps being of diminishing size, and again may trip and fall. For both these reasons there is need for enhanced levels of emergency lighting at escalators.

3.6.10 Curved passages

Where an escape route turns through an angle, it is good practice to locate emergency lighting luminaires and direction signs at such changes of direction. In the case of curved escape routes and passages, the luminous guidance devices should be placed on the outer side of the curve to give best visibility (Figure 3.3).

(b)

Figure 3.3 Scrap plans showing emergency luminaires (a) positioned on the outside of a curved passage for greater visibility, and (b) located to be visible along both arms of an angled corridor, (see Section 3.6.11)


3.6.11 Sloping floors, stairs

Sloping floors and ramps are particularly hazardous in the dark, and especially for elderly persons who may become confused and fall. Additional lighting will be needed at such locations, and it will be helpful if illuminated signing is provided (see Section 5.2.7).

3.6.12 Windowless buildings; long corridors

BS 558831 gives codes of practice for fire precautions in the design, construction and use of various kinds of buildings. In the case of windowless buildings, the point is made that one should distinguish between an 'emergency condition' and a 'lighting failure'. In the latter condition it is obvious that the emergency lighting should be operating; but in the former, there is no reason why selected luminaires, which form part of the normal lighting of the building, should not be activated by an alarm condition to ensure that there are no parts of the building in total darkness.

The above reasoning also applies to long unfenestrated corridors which form part of an escape route.

3.7 The designated place of safety

3.7.1 Objectives

An escape lighting system that enabled escapees to get out of a building in an emergency would not have performed its function adequately if in an emergency it results in a crowd of frightened people suddenly finding themselves in the open air, but in the dark without lighting and possibly still exposed to danger.

The Fire Precautions AcP requires that the means of escape to a place of safety 'shall be capable of use at all material times' - this phrase being construed to mean that sufficient and suitable lighting for escape shall be provided, and this surely should apply to outdoor areas. It is often wrongly assumed that, in an emergency, persons will be safe if they can simply get out of the building; in fact, the adjacent outdoor areas may contain many kinds of hazards (see Section 3.5), and so the need for 'escape lighting' may extend a considerable


distance from any building to enable escapers to reach a 'designated place of safety'.

If escapers were to remain in the close vicinity of the building which they have just left they could possibly be subject to further danger; e.g. • they may be in danger from falling debris or glass falling from

windows because of heat or explosion; • by crowding near an exit they may obstruct the free passage of

others escaping from the building; • if they remain close to the building they may be affected by smoke

or toxic fumes; • if they remain close to the building they may be subject to danger

because of the arrival of fire appliances and other emergency services vehicles (and may hinder their movements).

3.7.2 Requirements

There may be need for more than one designated place of safety relating to a particular premises, and there may a choice of routes thereto. The area near a final exit from the building, and the route from there to the designated place of safety may contain dense smoke. The presence of smoke or other hazard may determine which is the safest route.

In the absence of a specific legal requirement or other specification, it is proposed that the following requirements for the external route to a designated place of safety, and for the place of safety itself, should be satisfied: • The external route from the last exit from the building to the

designated place of safety shall be as straight, level and free from hazards as possible.

• The external route shall be suitably lit at least to emergency lighting standards (see Section 10.1); better still, that the lighting shall be of the order 10lux along the centreline of the route.

• To enable safe movement along the external route in conditions of smoke, clear low-level luminous signs or marking, or handrails (see Section 5.4) shall be provided.

• The external lighting shall not employ low-pressure sodium lamps, for these are devoid of colour-rendering property, and would


therefore make it more difficult for persons to identify other persons that they seek (e.g. lost children, friends from whom they have become separated).

Considering the requirements when a large number of persons have escaped from premises such as hotels, large retail stores, stadia etc, the following requirements would apply:

• Preferably the designated place of safety shall provide a measure of shelter from inclement weather, for the escapees may be in a state of shock and distress, and not ready immediately to depart from the site. In the case of persons who have escaped from residential premises (e.g. blocks of flats, hospitals, hotels), they may have nowhere to go to until arrangements have been made for them.

• It is desirable that at the designated place of safety there shall be facilities to assist escapees, e.g. first aid equipment (including oxygen), telephone, etc, and that a qualified First Aider be in attendance. It would be beneficial if a responsible person could be in attendance as soon as possible to give reassurance and to handle urgent matters for escapers.

4 Emergency lighting luminaires

4.1 Description

The terminology used in emergency lighting practice is confusing to those coming new to the subject, and there is not universal agreement on some of the terms. This is recognized in TM1210 which states that some of the terms used therein may be differently defined in other documents. Types of emergency lighting luminaires and internally illuminated exit signs are discussed in this section, while their modes of operation are described in Section 4.2.

(Note: In this Chapter, references to 'lamp' may be taken to mean 'lamp or lamps'.)

4.1.1 General functions of luminaires

The term luminaire is preferred to 'lighting fitting' or 'lighting fixture', as the latter terms are used to describe other electrical fitments. The quality requirements for all types of luminaires and internally illuminated signs, e.g. constructional features, optical performance, electrical safety and durability, are covered by BS 453317. The construction and enclosure must be appropriate to the duty and the environment in which the luminaire will function as follows:

• Mechanical

To physically support the lamp and enclose control gear, battery and charging circuit (if required) and to provide means of attaching the luminaire to a structure or support.

• Electrical

To provide electrical connections to the lamp and the electrical components, and means of safely introducing the mains connection or emergency supply as appropriate.

Emergency lighting luminaires 53

• Light control

To provide means of controlling the distribution of light from the lamp.

• Safety

(a) To provide enclosure of the lamp, control gear and electrical circuitry for protection against electric shock, burns etc.

(b) To protect the lamp and ancillary components from mechanical damage, and prevent the ingress of moisture, corrosive substances, dusts etc.

(c) To provide environmental protection against the effects of a broken lamp or the heat of the lamp and other components, so as to prevent fire and explosion being caused (see Section 7.4).

4.1.2 Types of emergency lighting luminaires

An emergency lighting luminaire may be described as 'single-point', 'slave', or 'combined':

• Single-point luminaire

An emergency lighting luminaire containing a lamp, a secondary-cell battery and a charging circuit to charge the battery from the mains. During failure of the mains supply, the supply to the lamp is derived from the integral battery. Note that it is possible to convert an existing normal-lighting luminaire to emergency use by the addition of a retrofit kit; in some cases, because there is not physical room within the existing luminaire to house batteries etc, the additional components may be housed in a separate compartment positioned not more than lm from the converted luminaire.

• Slave luminaire

An emergency lighting luminaire containing a lamp but no batteries. During failure of the mains supply, the supply to the lamp is derived from a remote source.


• Combined luminaire:

A single-point or slave emergency lighting luminaire which also functions as a normal luminaire (see Combined luminaires - Section 4.2.3).

4.1.3 Enclosures

It is generally a straightforward operation to provide emergency lighting in a factory or office where there is a 'normal dry atmosphere', for there are plenty of suppliers offering suitable equipment, typically with enclosures to IP2032. Especial care must be exercised in the selection of emergency lighting equipment for food premises, for hazardous areas and for other aggressive environments. There may be applications of emergency lighting in areas requiring protected types of luminaires (protected against entry of dusts and moisture, typically to IP6532), as well as corrosion-resistant and flameproof luminaires, and for these the choice of products on the market is limited. The best solution may often be to locate a central battery in a 'normal atmosphere' zone nearby, and to use bulkhead luminaires having appropriate enclosures as slave luminaires in the areas where special protection is required (see Section 7.4).

4.1.4 Lighting of non-luminous signs

Non-luminous emergency signs (e.g. those printed on wall-mounted placards or applied by painting on to a wall surface) require to be externally illuminated to the requirements of BS 52664. The illumination may be achieved by locating a suitable luminaire near each sign to cast light upon it, and such external lighting units may be of 'single-point', 'slave' or 'combined' construction (see Section 4.1.2). Local luminaires for lighting non-luminous exit signs may be operated in the 'maintained' mode (see Section 4.2.1), or in the 'non-maintained' mode (see Section 4.2.2). The latter is not preferred, as it is desirable that exit signs shall always be illuminated so that occupants and visitors become aware of the exit positions. For this reason the 'maintained mode' (see Section 4.2.1) or the 'combined' mode (see Section 4.2.3) are preferred for luminaires serving this duty.

Emergency l ighting luminaires 55

In the case of small luminaires designed to light signs externally, because there are no losses due to light having to pass through a diffusing medium, higher illuminances are easily obtained on the surfaces of such signs, or conversely the required illuminance can be achieved with a lamp of smaller power (and hence smaller battery capacity and at lower cost). The spill-light from such luminaires will contribute locally to the emergency lighting of the escape route.

If there are a number of emergency signs to be illuminated within an area, cost may be saved by making the luminaire for one of the signs of 'self-contained single-point' construction, and feeding a number of nearby slave luminaires from it so that its integral battery is, in effect, a small-scale central battery. To increase reliability, the 'zoning' principle may be employed (see Section 6.1).

4.1.5 Conversion kits

Modification kits are available to convert a wide range of 'normal' luminaires into self-contained emergency lighting luminaires; some kits convert luminaires into automatic self-testing lighting units (see Section 11.2.2, Figure 4.1). If performed in accordance with the

Figure 4.1 Modification kits are available to convert a wide range of luminaires into automatic self-testing emergency lighting units. (Photo: P4 Ltd) (see Section 4.1.5)


instructions provided by a reputable manufacturer of modification kits, such conversions may be entirely satisfactory and safe.

4.1.6 Variety of emergency lighting luminaires

Glancing through the technical literature of many lighting manufac-turers, one might have the impression that the main types of luminaires employed in emergency lighting were internally-illuminated exit signs, and diffusing overhead luminaires. In fact, a high proportion of exit signs are externally illuminated (Figure 3.1), and a very wide variety of luminaires, both self-contained and slave types, are employed to suit the locations and environments in which emergency lighting must be provided (Figure 4.2).

4.2 Modes of operation

An emergency lighting luminaire may be designed to operate either in maintained mode (see Section 4.2.1) or non-maintained mode (see Section 4.2.2). Combined luminaires (see Section 4.2.3) are usually operated in the maintained mode. In the following descriptions, the term 'lamp' may be taken to mean also a group of two or more lamps within the luminaire.

4.2.1 Maintained mode

The lamp is lit during normal use, deriving its power from the mains supply. On failure of the mains supply the lamp is switched automatically to the emergency supply which is derived from an internal battery or remote central battery.

In a variant design (known as 'switched maintained'), the lamp may be switched on and off while the mains are healthy, but, on failure of the mains, the lamp will light automatically from the emergency supply, irrespective of the local switch being on or off. The emergency supply may be applied via a solid-state converter


(a)

(b)

(c) Figure 4.2 Examples of the wide variety of types of luminaires employed in emergency lighting, (a) Self-contained fluorescent diffusing luminaire suitable for normal dry interiors. (Photo: Taison Lighting.) (b) 'Wallpackette III'® emergency luminaire housing a 28 W2D fluorescent lamp, and available for maintained or non-maintained duty. The enclosure is to IP65, suitable for interior or exterior applications. (Photo: Holophane Europe Ltd.) (c) Bardic 8860 self-contained luminaire containing an8W fluorescent lamp in an IP66 enclosure certified for Zone 1 and Zone 2 use. (Photo: Chloride Bardic) (see Section 4.1.6)


within the luminaire to provide an a.c. or d.c. supply to the lamp at the same or at a different voltage and/or frequency to that of the normal supply. Under mains-failure conditions the lamp may give a lower lumen output than when operating on the normal supply.

Maintained emergency luminaires employing fluorescent tubular lamps are common. The use of tungsten-filament lamps for maintained duty is not preferred because of their relatively short life. The use of high-intensity discharge (HID) lamps for emergency lighting has hitherto been regarded as impracticable because of their long restrike and run-up times; but, if such lamps were fed from an 'uninterruptible' electrical supply (see Section 6.3), or fitted with ignitors which ensured almost immediate restrike on reconnection to the emergency supply, their use in emergency lighting systems might well be considered.

4.2.2 Non-maintained mode

In non-maintained emergency lighting luminaires the lamp is not lit when the mains are healthy. This has the disadvantage that, even with the recommended standard and frequency of routine testing, the condition of the lamp and luminaire cannot be known until they are called on to perform. The use of non-maintained emergency exit signs is not recommended.

Note: Any emergency lighting luminaire containing one lamp or group of lamps, whether it is of 'self-contained' construction or 'slave' construction, could be operated either in 'maintained' mode or 'non-maintained' mode. In the latter case, if suitably wired it would still light on mains failure, even if the local switch was off. The switching of emergency exit sign circuits is not recommended.

4.2.3 Combined luminaires

These were formerly called 'sustained' luminaires, but the term has been changed to 'combined' because they can be switched so that their operation is not sustained.

A combined emergency lighting luminaire has two lamp circuits, one of which is energized from the emergency supply, and the other from the normal supply. If desired this can ensure that the


illumination is sustained at all times; however, combined luminaires can be operated with the mains-supply lamps switched or unswitched, and the emergency-supply lamps may be operated in either maintained or non-maintained mode, but the latter is not recom-mended for emergency exit signs.

4.3 Low-mounted floor-flood luminaires

The need to provide sufficient illuminance on the floor to facilitate safe movement along smokefilled escape routes is discussed extensively in this book (see Sections 1.2 and 3.3). This section examines one way of achieving a required illuminance along such a route. No specification or code of practice for the type of equipment discussed in this section yet exists, and the proposals are the author's recommendations.

4.3.1 The concept

To light escape corridors, the idea is proposed of installing small, wall-mounted (preferably recessed) luminaires, these being mounted no higher than 600 mm above the floor. The preferred disposition of such luminaires would be at spacings of not greater than 2 m on alternate sides of the escape corridor (Figure 4.3).

Section 5.4 discusses low-mounted way-guidance systems which provide luminous strips or luminous markers along escape corridors to guide escapers. Low-mounted floor-flood systems are an alternative to such way-guidance systems. It is proposed that the effectiveness of low-mounted floor-flood systems as an aid to escape would be much enhanced by the provision of white reflective guidance strips and direction symbols on the floor or lower walls of the escape corridor, these being illuminated by the floor-flood system. In all floor-flood systems, it is proposed that a white band of high reflectance of not less than 80 mm width should be provided on the floor adjacent to the walls, or on the lowest part of the walls. Additionally, the 'broad arrow' direction symbol discussed in Section 5.2 should be utilized in floor or wall markings to ensure that escapers


Figure 4.3 Sketch layout of low-mounted floor-floods mounted 3001 600 mm a.f.L, spaced at staggered 4 m pitches along an escape corridor, (see Section 4.3.1)

know in which direction to move towards the exit. A design for a small luminous 'broad arrow' direction sign for low mounting is discussed in Section 4.3.5.

4.3.2 Luminaire features

The proposed floor-flood luminaires would be designed to throw light only on the floor to provide an objective illuminance along the width of the escape corridor. The luminaires would either: • house a lamp (or lamps) fed from an emergency or standby supply,

and would incorporate a reflector system, louvers or other means of optical control to produce a very wide downward light distribution, or

• be 'daughter' units containing a fibre-optic emitter to distribute light from a remote 'mother' luminaire containing an efficient lightsource.


The units as described would be designed to present only limited brightness upward, but this would not preclude a possible design which incorporated a luminous directional 'broad arrow' sign (see Sections 4.3.5 and 5.2). If the luminaire is fully recessed, such a sign could be located above the part that emits the main beam; if the luminaire were a surface-mounted pattern, such a sign could be located on its upper surface (Figure 4.4); alternatively miniature separate direction signs could be provided (see Section 4.3.5) fed from the same or a different fibre-optic light supply.

Figure 4.4 Sketches of (a) recessed and (b) surface mounted low-mounted floor-floods incorporating 'broad arrow' direction signs and equipped with small fluorescent or filament lamp. If signs are not incorporated, separate signs as Figure 4.5 may be used, (c) Sketch of fibre-optic output fitting, of which approximately 40 may operate at distances up to 15 m from one lightsource, depending on choice of lightsource. (Acknowledgement to Absolute Action Ltd and Hero Electronics) (see Section 4.3.2)

Various constructional methods could be utilized, as well as a number of alternative light sources, but the concept of piping light to such units by fibre optics should certainly be considered, for this would enable non-electrical low-mounted floor-flood luminaires to be developed for wet or hazardous zones (see Section 7.4), the


lightsource being located in a nearby zone of normal atmosphere. It is also probable that a family of low-mounted 'daughter' floor-floods that were fed by fibre-optic light-guides from a 'mother' luminaire would be of lower capital cost and lower maintenance cost than the same number of luminaires of similar performance each containing a lightsource.

4.3.3 Objective illuminance

The objective illuminance along the centreline of the escape corridor would be not less than 0.2 lux minimum, and conceivably would be 5 lux minimum, or greater in particular situations (see Section 10.1). Low-mounted floor-flood luminaires as described could possibly be designed to produce average illuminances of the order of 10 to 50 lux over escape routes of 2 to 4 m width for special applications.

4.3.4 Applications

It is possible that the principle of employing low-mounted floor-floods might be adapted to the illumination of staircases which form part of an escape route. It would be important to prevent glare to escapers who have to ascend stairs so illuminated (from a basement for example; see Section 5.4). It is also possible that the principle of employing low-mounted floor-floods might be used for providing emergency lighting of open areas (for example, stepped terraces and seating areas in stadia), the luminaires being positioned around the periphery, and possibly also mounted on columns and other fixed objects within the area.

4.3.5 Miniature direction signs

Any system of low-mounted floor-floods or way-guidance system (see Section 5.4) must have means of indicating the direction of the nearest exit. A person leaving a room and entering an escape corridor must immediately be informed if he is to proceed to the left or the right, and for this a directional arrow sign is needed. It is believed


that a miniature luminous sign would serve this need adequately, and it is proposed that the 'broad arrow' sign could be displayed either: • on the upper surface of low-mounted way-guidance luminaires as

described, or • as separate units.

If the latter, the signs could be miniature luminaires each containing a lightsource (a filament lamp, cluster of miniature filament lamps, or cluster of LEDs), or they could be emitters fed by a fibre optic system (Figure 4.5).

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Figure 4.5 (a) Format for miniature luminous 'broad arrow' direction sign for use with low-mounted floor-flood systems or way-guidance systems. The arrow to show white against a black or dark green field. The light source may be subminiature filament lamps, electroluminescence, or LEDs, or the unit may be a diffusing terminal to a fibre-optic system, (b) Sketch of 'Lifeline'® electroluminescent low-level miniature 'broad arrow' direction sign. (Acknowledgement to Absolute Action Ltd and Hero Electronics) (see Section 4.3.5)


4.3.6 Discussion

Overhead emergency lighting systems designed to the general principles of BS 52664 work very well in smokefree conditions. It is suggested that the low-mounted floor-floods discussed in this section might in future be provided as an alternative lighting system to the BS 5266 method, and could be installed now as an additional facility. Experience may show that, in conjunction with suitable escape route signing (see Section 5.2), a low-mounted floor-flood system of lighting could become a valid sole method of illuminating escape corridors in the future.

An objection to the proposal in this section may be that the light from floor-floods may be obstructed by escapers; this is possible, but consider:

• when escapers are crawling under hot smoke, the bulk of the bodies of escapers ahead of one would generally be below the proposed mounting height of the floor-floods;

• if light from the nearest floor-flood is obstructed, one would still be within 2 or 3 m of the floor-floods behind and ahead of the obstructed floor-flood.

It will be seen that the low-mounted floor-flood concept could be a valid alternative to the use of way-guidance systems (see Section 5.4), but it is impossible at this stage to rank these systems in order of merit. This is one of the matters which might be investigated if a programme of testing and research was carried out on escape guidance in smokefilled areas as is proposed (see Section 3.3).

4.4 Some non-preferred equipment

4.4.1 Photoluminescent exit signs

In the present state of the technology of photoluminescence it is not believed possible to create an exit sign from such material that would approach the brightness and duration required by BS 52664.

Large areas of photoluminescent material, viz, a wall, might emit sufficient lumens to provide for safe movement. Perhaps the most promising application of photoluminescent materials is for outlining


doorways (in addition to other clear signing' see Section 5.2) and possibly for delineating the edges of steps and stairs.

4.4.2 Adjustable spotlight units

A unit comprising a battery container on which are mounted two or more directional lamps (typically 100 W PAR lamps) has been on the market for some years in the UK. In the author's opinion such equipment should not be described as 'emergency lighting' for the following reasons:

• spotlamps cannot provide good 'pilot lighting' for they are far too bright and would dazzle and confuse an escaper moving towards them;

• strongly directional lights cannot cast light forward through smoke, and once the escaper had passed them he would have what little light there is behind him and not in front where he needs it; further, in smoky conditions, the glare-back from light scattered and reflected from the smoke could impede his perception of his surroundings;

• spotlights on adjustable mountings may be easily pointed in the wrong direction or tampered with;

• for the small amount of functional value, such units are very expensive.

4.4.3 Certain portable lighting units

Various items described generally as 'portable emergency lighting' have been offered in the UK. In the author's opinion such items should not be described as 'emergency lighting' for the following reasons: • if not permanently installed they may be removed or stolen; • they are usually fitted with a line switch and so may be left

switched off, or not plugged in, so that the batteries may not be in a good state of charge when required for use.

However, under emergency conditions there may well be a need for portable lighting equipment of some kind to be brought into use, e.g. to augment emergency lighting for the continuance of essential tasks during a long failure of normal lighting (see Section 6.3.2).


4.4.4 Non-cut-off units having high brightness

There are offered for sale in the UK various patterns of luminaires claimed to be 'slave emergency lighting luminaires' which incorporate a low-voltage filament lamp. Some of these are of designs far removed from the objectives of BS 5266 in that they give very little effective control of the light output or are far too bright within the required cut-off angle.

A number of conventional and popular emergency lighting luminaires on the UK market which employ glass prismatic or imitation crystal bowl enclosures are also far too bright for the duty. Persons in emergency conditions of lighting may be highly susceptible to glare because of visual embarrassment (see Section 3.1). The control of direct glare from emergency lighting luminaires is a matter of importance, and overhead luminaires should provide cut-off at 70° from the downward vertical as seen by the person moving along an escape route in the direction of the exit.

4.4.5 Certain retrofit conversion kits

It is possible to convert existing normal-lighting luminaires to duty as maintained, non-maintained or sustained emergency luminaires, and satisfactory equipment to provide for this is available. However, there are some retrofit kits which are of dubious quality and may not be safe; for example, some units containing battery, charger etc, and designed to provide an emergency supply to one or more nearby existing normal luminaires may only be suitable for use in dry, clean atmospheres. The user should check that there is no fire risk caused by mounting such enclosures on vertical surfaces or the ceiling -some, for example, may exhibit surprisingly high surface tempera-tures. Attention should be paid to the method of making earth connections, and ensuring that testing etc can be carried out without exposing the operator to risk of electric shock.

4.4.6 Certain DIY self-contained units

The author has knowledge of a user who purchased a number of self-contained emergency-lighting units from a DIY store and


installed them in his small factory. Two of these units overheated and soon failed in service, and one actually caused a small fire. Investigation showed that the units were only safe if wall-mounted in a certain orientation, for when ceiling-mounted or mounted another way up, they overheated and became electrically unsafe. Following legal representations to the supplier, it is understood these products have been withdrawn from sale.

4.4.7 Solar-powered devices

Units of this kind have been offered in the UK, with the inviting instructions: 'Emergency lighting you can fit and forget! Let the sun charge the batteries for you. No mains wiring. No maintenance required.' Caveat emptor!

4.4.8 Certain units with connection leads

A representative demonstrated a self-contained luminous emergency exit sign to the author by plugging its flexible lead into a socket. He stated that some customers preferred to purchase these items 'complete with a 2m lead and plug'. Emergency lighting units should always be 'hard wired' (see Chapter 9).

4.4.9 Emergency signs with nonstandard legends

The occupier of some premises purchased a number of self-contained sign luminaires, and took advantage of the supplier's offer to supply signs with wording to the customer's requirements. The occupier used signs bearing the words 'NO EXIT' at certain doorways, and was forced to remove them on the instructions of the Fire Prevention Officer.

5 Luminous emergency signs and way-guidance devices

5.1 Functions of luminous emergency signs

For emergency signs to fulfil their function, the signs themselves must be clearly delineated and properly illuminated all the time the premises are occupied (see Sections 5.1.1 and 5.2). They must be located correctly (see Section 5.1.2), any wording must not mislead the reader (see Section 5.1.3) and the symbols must not be misused (see Section 5.2.11).

5.1.1 Signs giving a clear unambiguous message

The following functions should be fulfilled at all times that the premises are occupied, and not only when there is a failure of the normal lighting or some other emergency condition exists:

• to enable persons to identify exit doors which will enable them to reach a designated place of safety;

• to enable persons to identify escape routes which lead to exit doors;

• to enable persons to locate fire alarm points, fire hoses and extinguishers;

• to provide persons on the premises with reassurance as to their safety at all times.

Emergency signing also has a training function, in that persons on the premises consciously or unconsciously come to learn the locations of the exits, escape routes and fire equipment (see Section 3.6.6). This is possible only if the emergency signs are illuminated during all the hours of occupancy, i.e. if they are operated in the maintained or sustained mode (see Section 4.2), and if they are bright enough to be clearly visible in the presence of daylight or the normal lighting.

Luminous emergency signs and way-guidance devices 69

5.1.2 Wrongly located signs can give a confused message

It is essential that emergency signing shall be clear and unambiguous. It should be noted that, to some extent, the implied meaning of a sign may change according to its situation.

An example of bad signing is as follows. In the consulting rooms of a medical group practice, the exit route from the consulting rooms to the street door was via the waiting room. Thus, as seen from the consulting-room side, the door into the waiting room was the escape route. In attempting to make this quite clear, a painted EXIT sign was fixed to the inner side of the door, i.e. on the side of the door nearest to the consulting rooms. The door was fitted with a self-closing device, but what had not been foreseen was that it became customary to prop that door open with a chair, with the result that the word ΈΧΙΤ could be seen from the waiting room side. This gave the impression to persons in the waiting room that the door was the route to an exit, which it was not - a potentially dangerous situation.

5.1.3 Wording on exit signs

Currently, the normal wording consists of the word 'EXIT. If there is an exit the occupier does not want the public to use normally (for example, that leads through a stock room or private area) but which could be used in an emergency, the words 'EMERGENCY EXIT' or TIRE EXIT' may be used.

It has been proposed from time to time that exits which are intended for use only in emergency conditions should be fitted with Occulting signs', viz. signs which are normally blank and not illuminated, but which display a legend such as ΈΧΙΤ' when internally illuminated. Such signs are not approved as they are not visible and illuminated when the public are on the premises, users of the building do not have the opportunity to learn (perhaps even subconsciously) the layout of the premises and the locations of the escape routes.

Unapproved but used in a few premises is the legend 'WAY OUT' - or even OUT'. Under no circumstances should the words 'NO EXIT' be used, for, in a time of emergency, such could easily be mistaken for ΈΧΙΤ', possibly with tragic results. Current thinking is tending towards the elimination of all wording on exit signs, and the use of symbols only (see Section 5.2.2).


5.2 Escape route signs

Fire safety signs are covered by BS 5499.199112, Part 2 of which specifies self-luminous signs. The objectives of escape route signing are reviewed in Section 5.1. This section reviews the required features of escape route signs, and conjectures on possible future practice.

5.2.1 Identifying the escape route

Factors which must be considered in order to make an escape route as safe as possible will include: • The signing must show the way clearly, with minimum possibility

of escapers misreading the signs (see Sections 5.1.1 and 5.1.2). • The signing must allow for there being more than one possible way

out, and the signing at places where there is a choice of route should be unambiguous.

• Signs may be needed to give additional information such as where the escaper will come to ramps or stairs, or to indicate locations of extinguishers and fire call points.

5.2.2 Signs with wording

BS 5499.199112 stipulates the use of green letters on a white field (or reversed), with letter size up to 125mm high (designed to be legible in clear air at a distance of 50 m). Signs may be internally or externally illuminated.

A good case can be made for discontinuing the use of the legends 'EXIT and 'EMERGENCY EXIT' on emergency signs. The following factors may be considered:

• Illiteracy

There is a high incidence of illiteracy world wide. According to a report of the OECD (Organization of Economic Co-operation and Development)18, illiteracy is no longer restricted to Third World countries; several million people in the most advanced nations of Europe cannot read or write. In Germany it is estimated that three million adults are functionally illiterate; of 500,000 men aged 18—23


called up for military service in France, one in five could not read a simple 70-word text. The United States labour secretary ack-nowledged recently that 20 per cent of US high school graduates could not read their own diplomas. Similar conditions exist in the UK, with the added problem that around one million people in the population can read only languages which do not use our alphabet, e.g. Arabic, Greek, Hebrew, Russian (Cyrillic characters), Sanskrit, Urdu etc. Further, it is illogical to use signs which, in an emergency, could only be recognized by children if they have learned to read. At any time, there are very large numbers of persons visiting the UK who are literate in a European language in which the word ΈΧΙΤ' is not used.

• Visual defect

Considering only persons who have nominally normal vision, about 15 per cent of the population have some degree of visual defect and (according to the author's random testing of a small sample) cannot read letters 10 mm high at a distance of 1 m. Of course, most people have their visual deficiency optically compensated by spectacles or contact lenses - which might easily be displaced during an emergency; thus, an appreciable proportion of the literate population would be unable to read the word 'EXIT' under typical emergency conditions.

5.2.3 The 'running man' pictogram

For reasons such as are cited in Section 5.2.2, the 'running man' pictogram as specified in ISO 6309 (Figure 5.1) has been adopted.

Figure 5.1 'Running man' exit pictogram. (see Section 5.2.3)


Until 1991, externally and internally illuminated signs for use in installations meeting BS 52664 were required to have the word ΈΧΓΓ or TIRE EXIT' in conformity with BS 5499:1980 (with-drawn) and BS 2560:1978 (withdrawn), both of which are superseded by BS 5499.199012. All exit signs are now required to show a graphic symbol or the pictogram to indicate a safe exit. For an initial period, which has not yet been defined, such signs must be used to indicate ordinary exits. It is expected that, where appropriate, signs at egresses which are to be used only in a fire or other emergency will have to show the word ΈΧΓΓ or TIRE EXIT', or perhaps 'EMERGENCY EXIT'.

Various objections to the use of the 'running man' pictogram have been expressed, including:

• A running figure suggests that escapers should run along the escape corridors - which would be bad advice.

• The 'running man' pictogram is used in two forms: running to the left (to be used at an exit to the left), and running to the right (for an exit to the right, or straight on, or up, or down). Thus the escaper has to puzzle out the actual meaning of the sign at a time when seconds count.

• Such a crude cartoon character that does not clearly indicate its meaning is unsuitable for conveying £n important message upon which lives will depend.

• From a distance, the 'running man' pictogram appears just as a mottled blurred image, and only becomes clear when one is closer to it. (It is understood that long distance legibility was not an objective of the devisers of the pictogram, who rely upon the wording shown with the pictogram to clarify its meaning as the escaper approaches the sign!)

Based upon the above considerations, it is the author's earnest hope that the 'running man' pictogram will have but a short life, and that it will soon be entirely replaced with a simple arrow sign (see Section 5.2.5) which, in the author's opinion, will more certainly fulfil the desired function.

5.2.4 Escape-route signing

In designing escape route signing, much can be learned from our experience in the use of signs for the control of road traffic. Some


years ago it was considered necessary to display legends on street bollards such as 'KEEP LEFT', 'KEEP RIGHT' and even 'PASS EITHER SIDE'. The present system of simple arrow signs specified by the Department of Transport (and used fairly consistently throughout the world) perform their duty excellently, and there are no problems of having to read wording in order to divine the meaning of a sign (Figure 5.2).

It can be argued that traffic signs are intended to be read by motorists who have normal or corrected vision; but the speed with which signs have to be comprehended by a driver in a moving vehicle puts the driver's visual task on a par with the recognition problem experienced by an escaper on seeing an exit sign - in other words, both forms of signing have to convey extremely important information in a fraction of a second. Imperative traffic signs use the 'broad arrow' symbol; this may be displayed within a circular field, though this is not a constant practice.

It is suggested that the Department of Transport pattern of 'broad arrow' traffic sign currently in use (Figure 5.2) could be used as the blueprint for the emergency signing of all escape corridors. An example of the use of the 'broad arrow' symbol is seen in the 'Ecolight'® exit signs of Saunders-Roe Developments (Figure 5.3). It is the author's strong recommendation that the 'broad arrow' should very soon become the only symbol to be used to indicate an escape route to an exit (Figure 5.4), and to signify the exit itself (Figure 5.5). Such a policy would not preclude the use of the means to emphasize the outline of an escape door and make it more easily visible in smoke, such as:

• photoluminescent strip; • electroluminescent strip; • luminous strip containing subminiature filament lamps; • luminous strip containing LEDs; • fibre-optic luminous strip.

5.2.5 Luminous 'broad arrow' exit and direction signs

It is the author's opinion that in applications where a luminous 'broad arrow' sign is mounted at 2 to 2.5 m nominal height, a dark arrow (dark green or black) silhouetted on a bright background would be


Figure 5.2 Typical applications of the Department of Transport 'broad arrow' symbol in traffic signing (see Section 5.2.4)


Figure 5.3 Examples from the range of Ecolight® self-contained emergency 'EXIT signs which employ electroluminescent displays having a lamp life of around 70,000 hours (about 8 years) of normal use. (Photo: Saunders-Roe Developments), (see Section 5.2.4)

Figure 5.4 'Broad arrow' symbols (a) pointing upward to indicate 'Go straight on', (b) pointing downward to indicate an exit, (c) used with wording to show the direction to an exit (may point to right or left), (d) used alone (may point to right or left) (see Section 5.2.4)


M

SL LUMINOUS STRIP TO ENHANCE VISIBILITY OF THE EXIT IN THE PRESENCE OF SMOKE

e Figure 5.5 High-mounted and low-mounted self-illuminated 'broad arrow' signs used to designate an exit. The door may be outlined by a luminous strip which may be of photoluminescent material, electroluminescent material, or may contain subminiature filament lamps or LEDS, or may be a fibre-optic luminous strip (see Section 5.2.4)

appropriate, as an aid to recognition from a distance - say up to 30m or more.

The 'broad arrow' symbol would also be appropriate to use in small low-mounted luminous direction signs along exit routes, and to give directional orientation to persons traversing an exit corridor by low-mounted floor-floods (see Section 4.3.5) or following a low-mounted way-guidance system in smoke (see Section 5.4). In such applications it is recommended that the 'broad arrow' symbol be used in reversed format (white on black or dark green).

5.2.6 Other signing along escape routes

There is considerable value in reminding occupants of buildings about escape routes during normal occupancy so that the occupants learn about the building layout - perhaps even subconsciously; it is for this reason that exit signs should be illuminated during all the hours that the premises are occupied.

Unlit repeat symbols could be used in locations such as large open-plan offices, or in large machine shops, where a sign showing the reversed format of the 'broad arrow' symbol (white on black or


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Figure 5.6 The reversed form of 'broad arrow' symbol (white on black or dark green) can be used as a repeat symbol and reminder to occupants of the direction of the nearest fire exit. Sign could be made of photoluminescent material, (a) Typical dimensions and positioning; (b) an example in use (see Section 5.2.6)

dark green) could be affixed to any convenient vertical surface so that the top of the sign is 300 mm above the floor (Figure 5.6). Such signs could be made of photoluminescent material, and self-adhesive.

If important information about the nature of the escape route which would be of value to an escaper must be displayed along the escape route (e.g. approaching a ramp or stairs), this information can be conveyed without causing any confusion by displaying it in symbol form within a red triangle frame, generally in the style of Department of Transport cautionary signs (Figure 5.7).


Figure 5.7 Signs to indicate hazards along an escape route. Colours: black on white within a red triangle (see Section 5.2.6)

5.2.7 Non-escape route directions

In the current arrangements recommended by the Department of Transport for traffic signs, the 'broad arrow' is used only for imperative instructions. Directions in which the motorist may proceed optionally are distinguished by the use of the 'chevron arrow' (Figure 5.8). It is suggested that the Department of Transport 'chevron arrow' could be used as a blueprint for all non-escape-route directional signing in premises, e.g. where it is desired to indicate the direction to a place or department etc, but where such signing is not intended to aid escape from the premises, and the indicated direction is not necessarily a route to an exit (Figure 5.9).

5.2.8 Colours of signs

A strong argument exists for emergency exit signs to emit only white light (see Section 3.1), and the preferred colour for the 'broad arrow' symbol on all exit signs would be black on a white field. However, following the common convention, it is suggested that on high-mounted internally-illuminated emergency signs having a white luminous field, the 'broad arrow' symbol could be coloured dark green if presented on the white luminous field so it is seen as a dark silhouette when the sign is illuminated.

Chevron arrows, used for non-escape-route signing (Figure 5.9), should not be coloured green. They could, for example, be black or dark brown on a white background.


Figure 5.8 Typical applications of Department of Transport 'chevron' symbol to impart non-imperative information for traffic direction (see Section 5.2.8)

W Staff Shop

Figure 5.9 'Chevron' symbol used on signing to give non-escape-route information. Colours: black or brown on white (see Section 5.2.7)

5.2.9 Educating the public

If the 'broad arrow' symbol were adopted to indicate all emergency escape routes, it is likely that many members of the public would at once recognize its significance, and many would soon come to associate the symbol with exit routes; none the less, there would be

Stores >


need for a public education programme so that all members of the public shall come to understand the significance of the symbol as soon as possible. The information should be communicated in English and in the many languages in use by minorities in the UK (for example in leaflets or by public information messages on TV), and also by the use of mime and cartoons without need for words. It would be advisable to retain the word 'EXIT on signs for a period while the public was becoming familiar with the 'broad arrow' symbol in this application, but in time the wording could be dropped and only the symbol used.

5.2.10 Misuse of emergency symbols

Many large premises have need for internal signing to direct staff and visitors to various locations on the premises. In a factory in which a good standard of emergency lighting and emergency signing had been provided, some new signs were erected, pointing the directions of the canteen, personnel office, accounts office, stores, etc. The person responsible for putting up the signs could not have given much thought to the matter, for the signs incorporated the 'broad arrow' symbol which could lead persons unfamiliar with the premises into believing that the routes indicated were escape routes. It is recommended that direction signs other than those for escape routes should use the 'chevron arrow' symbol (Figure 5.9), not the 'broad arrow' symbol (Figure 5.4).

5.3 Non-electrical escape route signs

Provided they comply with the requirements of BS 5499:1991 for fire safety signs12, escape route signs of any construction may be employed, for example, those illuminated by gas.

Still in use, but of currently declining popularity, are exit signs which are self-luminous by virtue of containing a phosphor which is activated by a radioactive material - usually titrium. Because they do not require an electrical supply, these signs are suitable to use in flame-hazard areas. They are required to comply with Part 2 of the standard, and usually have letters 125 mm high which are designed to


be visible at a distance of 26 m during the effective life of the sign. Because they do not require the regular inspection and testing necessary for battery-operated exit signs (see Chapter 11), titrium-activated signs are often employed in places where maintenance is difficult.

Titrium-activated signs have several serious disadvantages: • Their characteristic is to give a steadily declining luminance

throughout life; unfortunately they may be entirely neglected and left in situ until approaching extinction (i.e. below the minimum required luminance of 2Cd/m2), with consequent reduction in safety for the occupants of the premises.

• Those having the responsibility for maintenance of titrium-activated signs are usually unable to measure the brightness of the signs, and must rely upon the manufacturer's guidelines, a projected date for replacement being given at the time of purchase. With changes of staff likely to occur more frequently than the replacement period of the equipment, this is easily forgotten (see Section 11.1). Further, because it is unlikely that the user would carry out daily inspections as required by BS 52664 for luminaires containing lamps, self-luminous signs are likely to be so neglected as to be obscured by dirt.

• Because they contain radioactive material, time-expired titrium-activated signs must not be disposed of along with ordinary waste or garbage, but must be returned to the original manufacturers for safe disposal. Unfortunately this important fact may not be known to persons currently responsible for their care, and illegal dangerous disposal may occur.

5.4 Luminous way-guidance systems

5.4.1 Background

After many years of appearing to ignore the problem, even the experts in the emergency lighting field are now admitting that overhead emergency lighting systems have little value in smokefilled premises, and agree that exit signs mounted at 2 to 2.5 m above the floor are valueless when smoke is present (see Section 3.2). Low-mounted way-guidance systems may be used at present in the


UK provided the requirements of BS 5266* are also satisfied. Way-guidance systems are being studied in many countries and may soon be widely adopted. It is understood that such systems (known rather confusingly as 'proximity lighting') are already a legal requirement, or will shortly become so, in parts of the USA.

Sections 3.1 to 3.4 inclusive indicate the value of low-level way-guiding systems in enabling persons to make their way along escape routes in conditions of smoke and/or in densely crowded conditions. Section 4.3 discusses low-mounted floor-flood luminaire systems which may be used for illuminating escape corridors. The present section discusses practical systems of way-guiding.

5.4.2 Visual requirements

In smoky conditions, whether walking or crawling on hands and knees, the escaper needs visual guidance, that is, he needs a continuous luminous strip or a series of luminous devices that he can follow. Contrary to the requirements for conventional emergency lighting and low-mounted floor floods, a way-guidance system need not shed a significant level of illuminance on the surroundings, its function is primarily to be visible by its luminosity. However, some way-guidance systems now available are claimed to emit sufficient light to satisfy the illuminance requirements of BS 52664, e.g. the GuideLite® 'SCM' range marketed by Existalite Ltd (Appendix A) (Figure 5.10), and so presumably - with the agreement of the enforcing officer - could be employed without any provision of conventional overhead emergency lighting.

A way-guidance system may consist of a continuous luminous strip, or may comprise a series of luminous devices arranged linearly so that when the escaper is adjacent to one he can see a continuation of the luminous strip, or - where an array of discrete luminous devices is used - at least one other luminous device ahead. The actual luminance of the way-guiding strip or line of devices that is needed to ensure clear visibility will depend on the luminous area projected towards the observer's eyes, but luminances of the order of 20 to 80 Cd/m2 are believed to be necessary for a continuous illuminated strip of about 30 mm wide. The visibility of a strip containing a series of small bright sources could be considerably higher than that of a uniformly luminous strip emitting the same number of lumens per


Figure 5.10 Demonstration of way-guidance in smoke conditions using Existalite /GuideLite'® strip which employs an array of sub-miniature low-voltage filament lamps (Photo: Existalite Ltd) (see Section 5.4.2)

unit length, for example, a strip bearing a series of small bright emitters such as LEDs or miniature tungsten-filament lamps.

Way-guidance luminous strips or arrays of luminous devices may be either recessed into the floor (Section 5.4.3) or wall-mounted (Section 5.4.4).

5.4.3 Floor-recessed way-guidance systems

If recessed into the floor of escape corridors not wider than 2 m, way-guidance devices will preferably be located along the centreline of the escape corridor, but could be installed along both edges of the floor. In the case of escape corridors wider than 2 m, two or more luminous strips or arrays may be needed to ensure there is an adequate standard of visibility, e.g. the escaper should not be more than 2m - and preferably not more than 1.5m - from luminous guidance.

The construction of floor-recessed way-guidance systems should be such that they will not be damaged by being walked on, and be


capable of withstanding the pressure of objects, wheeled trolleys etc without damage. If the floor is carpeted, means may be devised to hold down the edge of the carpet with the channel which contains the way-guidance equipment. Where appropriate, a floor-recessed way-guidance device must be capable of withstanding water, damp or any other adverse environmental condition that may be present.

5.4.4 Wall-mounted way-guidance systems

Wall-mounted way-guidance systems should be mounted not higher than 300 mm above the floor, and may be fully or partly recessed, or surface mounted. If surface mounted, it will be preferable if the luminous strip or array of luminous devices is continuous in construction or is mounted within a continuous channel so there are no projections which would cause injury or impede movement under very crowded conditions. In the case of systems which consist of a series of luminous devices, if they cannot be 'streamlined' to prevent injury or impediment to movement, it would be preferred for these to

Figure 5.11 Way-guidance system using subminiature filament lamp arrays in strips mounted just above the skirting boards, and framing doorways (Photo: Existallte Ltd) (see Section 5.4.4)


be recessed flush with the wall. There is much to be said for locating way-guidance strips and devices at the angle of the floor and wall or just above the skirting-board (Figure 5.11).

5.4.5 Luminous sources for way-guidance systems

At the time of writing, several way-guidance systems are on the market, and it is known that other UK manufacturers are developing such systems. The following notes relate to products under consideration, in development, or available now.

• Titrium-activated self-luminous devices

These are not recommended and, as far as can be ascertained, no practical way-guiding system using this type of luminous source is likely to come on to the market. The difficulties of application mainly concern the practical matter of ensuring that linear elements shall remain sealed to prevent the escape of radioactive gas. The relative fragility of such devices makes them unsuitable for recessing into floors. However, it is possible that wall-mounted or wall-recessed self-luminous signs of this construction, displaying the 'broad arrow' directional symbol (see Section 5.2.5), could be used in association with way-guidance luminous strip devices which do not in themselves provide an indication of the direction to be followed. Devices of this kind are thought unlikely to be bright enough to provide way-guidance by themselves.

• Photoluminescent materials

Known examples of this type of material do not appear to provide sufficient luminance or sufficient duration to perform the task of way-guiding adequately. The luminance of photoluminescent mate-rials decays in a matter of hours after exposure to light, and this introduces a factor of uncertainty as to the brightness that will be exhibited at any time; if, for example, the area concerned was not provided with adequate daylight, and the normal lighting was not in use, the small amount of energy stored by the material would decay so that its brightness and effective duration might be insufficient in an emergency. However, the use of photoluminescent material as an


auxiliary means of signalling obstructions and outlining exit doors has much to recommend it.

It is understood that at least some photoluminescent materials are unable to withstand the temperature of hot air or hot smoke which may be present in a fire, and that such materials may be permanently damaged by such exposure. This does not seem a good enough reason not to use these materials.

• Light emitting diodes (LEDs)

Electroluminescence is the phenomenon of visible light being emitted by substances when subjected to electrical stress. This is the principle of the light emitting diode (LED) which emits light when the crystal material within it is subjected to a constant electric field. Arrays of LEDs may be utilized in strip form to form a way-guidance system such as is available from companies such as Defence Components Ltd (Appendix A).

In the Guide-Lite® System from Existalite Ltd (Appendix A), one form of their continuous linear system (the 'SCD' LED range) utilizes LEDs arranged to have a strongly directional property along the axis of the strip to enhance the guidance properties of the system.

• Electroluminescent (EL) strips

Electroluminescent plastic sheet materials emit light from phosphor materials which are subject to an alternating electric field, the phosphors commonly being doped inorganic crystals. Such materials have been known for many decades but, because it has hitherto been impossible to raise their luminous efficacy significantly, they have not developed into practical illumination light sources as had once been hoped, and their application hitherto has been limited to some specialized uses such as emergency signs in aircraft. A new chapter to this story is now being written, for improved materials with enhanced electroluminescent properties have been developed (Figure 5.12).

Describing the construction of a product of DCL Defence Components Ltd (Appendix A), the back of EL strip and sheet materials may be formed from thin aluminium sheet, while the front of the strip is formed from a transparent conductive film. In order to achieve the desired distribution and uniformity of brightness from the


Figure 5.12 Demonstration of way-guidance in smoky conditions using 'Lifeline*® electroluminescent strips set in the angle between wall and floor (Photo: Absolute Action Ltd in association with Hero Electronics) (see Section 5.4.5)

emissive surface, dedicated current paths or 'bus bars' are added to the transparent electrode by deposition. The resultant assembly -which has the electrical characteristics of a capacitor - is completed by encapsulating the material between two environment-resistant transparent layers. Thin profile EL strip materials of this kind are claimed to offer low power consumption, long life and high reliability, coupled with a rugged construction that will survive in severe environments.

• Filament-lamp linear arrays

The sub-miniature lamps as used in the GuideLite® 'SCM' system from Existalite Ltd (Appendix A) have a life of upwards of 40,000 hours (approaching five years of continuous operation), and are operated on a 24 V SELV (safety extra low voltage) system. The intrinsic brightness of such lamps is high (up to 2480 Cd/m2), giving excellent guidance characteristics in dense smoke conditions (Figures 5.10,5.11 and 5.13)


(a) (b)

Figure 5.13 A method of outlining a door with way-guidance strip containing subminiature filament lamps. The strips are powered by the battery in the exit sign which contains one 12 inch 8 W fluorescent lamp. The exit sign battery also powers the two low-mounted exit signs in which the letters are formed in LEDs, (a) On mains failure, (b) 40 seconds later in typical smoky conditions when the conventional exit sign is invisible from one or two paces. (Photos: Existallte Ltd) (see Section 5.4.5)

• Fibre-optic systems

Although the applications technology of fibre-optics is still in its infancy, there is plenty of evidence that light-piping will become a dominant feature of many applications of lighting in the future1'20. Fibre optics have already found some applications in emergency lighting, where the use of an efficient lightsource to pipe light to a number of satellite luminaires brings the benefits of reduced maintenance, and possibly lower installed costs and running costs (see Section 4.3.2). Fibre-optic technology seems to have a particularly promising future in the provision of way-guidance systems as is indicated by the way-guidance strips developed by Absolute Action Ltd (Appendix A), where the distribution of light can be tailored exactly to the optical requirements, e.g. to project luminous flux preferentially in a desired direction, or to produce overall brightness of the strip, or to produce a bright edge or side to the strip etc. (Figure 5.12).


• Directional signalling feature

In a linear array of small lightsources, it can be arranged for sources to be switched sequentially to produce an apparent movement. For example, if all the sources were extinguished, and were then lit and extinguished rapidly in sequence, the eye would perceive this as a single source moving along the array. Conversely, if all the sources were lit, and then each was extinguished for a brief period in sequence, the illusion of movement would be created. Sources may be switched singly or in groups to produce the effect.

This feature may have applications in imparting a directional signalling property to low-mounted way-guidance systems. For example, a person entering an escape corridor from a side entrance would be instantly informed of the direction in which to proceed. Of course, other methods of giving this directional information may be employed, including the use of directional arrow signs (see Section 5.2).

• Other way-guidance systems

Continuous illuminated handrail systems may be used for aiding escape on the level, on inclines, along curved passages, and on stairways. An important application is on platforms of underground platforms for which a special handrail/emergency escape guidance system is manufactured by Industrolite Ltd (Appendix A) for London's Underground (Figure 5.14).

• Laser systems

The following information has been gleaned from an editorial report in a journal21 and from a press release issued by Mr Brian Perry22

who claims to be the inventor of the 'Ariadne'® emergency lighting system for which it is understood he has made patent applications.

The system is claimed to be 'a desirable extension to existing escape systems', and is said to be an escape system indicating direction 'like cat's-eyes on roads' by utilizing a continuous luminescent beam to identify one or several escape routes. It is claimed that the system can be activated automatically by means of fire or smoke detectors and a central control panel will graphically


Figure 5.14 Illuminated handrail system developed for London's Underground. (Photo: Industrolite Ltd) (see Section 5.4.5)

show the location of smoke, fire detectors, the architecture of the premises and the laser beams themselves.

The technical details issued so far are scant, but describe a 'highly columnated [sic] monochromatic and coherent beam of light, imperceptible in dust-free air [which] becomes highly visible when the minute particles present in dust or smoke act as a diffuser'. It is claimed that the invention 'affords an early-warning system and [will] sustain the "cat's-eyes" effect during the fiercest of smoke conditions, to a point when visibility and even life is lost, but where such directional information can be vital to the Fire Brigade.' It is claimed that the use of optical devices, beam-splitting and fibre-optic techniques permit the laser beam to be bent to follow a non-linear


path or 'be used for alternative signalling purposes'. It is claimed that the system's signals are visible where other forms of lighting are obscured by smoke. Another feature claimed is the use of laser beams to illuminate holographic signs.

If this invention is a genuine advance in the technology of escape lighting, then it deserves every encouragement; but the following points should be considered:

• The triggering of emergency lighting systems by detection devices is not new. Any system of emergency lighting can be so controlled and supervised by an 'intelligent' fire-control system (see Section 8.5).

• A collimated monochromatic beam of coherent light presents a potential danger, for laser beams must be efficiently guarded, or blindness or permanent damage to vision may be suffered by a person into whose eyes such a beam entered.

• It is claimed that the laser beam is luminous in smoke so that it could be used as a way-guidance device; but that it is invisible in clear air. Thus it could give no way-guidance in clear air conditions (which are the most common conditions under which persons need to escape from premises, e.g. on simple failure of the normal lighting).

• The issued material indicates the use of a laser beam to detect the presence of smoke, apparently by splitting the beam so that part goes through a clean volume of air and part goes through a volume of air which may be contaminated, and the difference in transmitted light detected. The effectiveness and reliability of such an elaborate means of detecting smoke are unknown, but the method does not appear to give any advantage over other known methods of smoke-detection.

• One is unable to imagine what benefit would arise from having 'holographic exit signs' as discussed in the sources quoted, and one must doubt if such could satisfy the requirements of BS 52664 and BS 549912.

6 Power supplies for emergency lighting

Choices as to the disposition and type of batteries to be employed are critical to the economy of an emergency lighting system, affecting both the capital cost and the cost of maintenance throughout the life of the installation.

6.1 Disposition of batteries

Batteries for emergency lighting are usually secondary (rechargeable) cells. Batteries may be integral (a battery is located within each single-point luminaire) or remote (a single battery supplies a group of luminaires). Neither method is clearly superior for all sizes and types of installations. Both methods may be employed in a single installation.

6.1.1 Integral batteries

Each luminaire or sign having an integral battery will require to have an internal charging device, as well as circuitry to detect and respond to mains failure. These features add to the initial cost of such units which also have a higher cost of maintenance per unit than do slave luminaires. The use of single-point luminaires with integral batteries is popular because of the simplicity of the wiring installation.

6.1.2 Central battery

A central battery provides the emergency power supply to a number of slave luminaires which may be located on more than one floor of a building or in more than one building. The central battery and its

Power supplies for emergency lighting 93

charger, etc may be located in a special room or in a plant room, and there may be associated generators for stand-by supply (see Section 6.3).

A central battery system is often the most economical method to employ where there is a large number of emergency luminaires and signs; but if many lighting points are located at considerable distances from a possible location for the battery (involving high costs of cabling and difficulties due to voltage-drop) then integral batteries may be more economical. A practical solution may be to have a central battery to supply most of the luminaires, and to employ self-contained luminaires for situations distant from the core of the installation.

For emergency lighting and signing in hazardous atmospheres, a central battery system may be preferred because the use of slave luminaires and signs will require less maintenance to be carried out on them, perhaps under difficult environmental conditions (see Section 7.4).

6.1.3 Zonal batteries

Instead of having a single central battery, a number of smaller zonal batteries may be employed. These typically will be self-contained battery cubicles each incorporating its own charger, and each providing power for the emergency luminaires in an area.

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ό Figure 6.1 Zonal battery system. The two areas have individual battery cubicles, Wand 'Β'. Each cubicle supplies a small number of selected luminaires (shown as 'a' and 'b') in the adjacent area to give greater security of lighting (see Section 6.1.3)


This arrangement may be cheaper than having a single large battery which requires special accommodation. The zonal battery units may be metal cabinets which can be located in any well-ventilated room that has a 'normal atmosphere' (e.g. no special environmental hazard). The reliability of such an arrangement is as good as for other systems, but an extra degree of security can be achieved by connecting some key lights in each area to the zonal battery cubicle in another area (Figure 6.1). This concept can be utilized in the horizontal, or to provide interconnections between floors in a multistorey building.

6.2 Selection of battery type

The choice of type of battery for an emergency lighting system should take account of factors such as capital cost, maintenance require-ments, expected life of the equipment, and its suitability for specific duties in terms of battery life and maintainability (see Section 6.2.1) and battery duration (see Section 6.2.2).

6.2.1 Batteries for self-contained units

The batteries used in self-contained emergency lighting luminaires and signs are most commonly of the sealed lead-acid type or sealed nickel-cadmium type. The maker's instructions regarding which way up such batteries are to be mounted should be followed. The life of sealed batteries will be shortened if they are subjected to elevated temperature, for example, as occurs in some maintained or combined luminaires, or if the units are in hot environments (e.g. bakeries), or if they are mounted above a source of convected heat (e.g. furnaces).

• Sealed lead-acid batteries

The cells of these are unvented, and require no topping-up of the electrolyte. They give best service if regularly cycled through normal discharge/charge, and if not subjected either to overcharge (being charged for long periods above the trickle-charge rate) or prolonged discharge (discharged beyond the rated capacity). These batteries


should not be left for long in a discharged or partially-discharged condition. Batteries of this type of suitable capacity may also be used for small central systems (say, up to six luminaires). The rated life is 4 to 10 years.

• Sealed nickel-cadmium batteries

The cells of these batteries are unvented, and require no topping-up of the electrolyte. Capacity may be reduced if they are subjected to prolonged overcharge or over discharge. Some loss of capacity may occur if these batteries are not put through a normal discharge/charge cycle occasionally, but this effect is not so marked as for lead-acid cells. They will tolerate being left for long periods in a partially-discharged condition. The rated life is 4 to 7 years.

6.2.2 Batteries for central-battery systems

The batteries used in central-battery systems are usually vented lead-acid batteries or vented nickel-cadmium batteries. Batteries of these types of suitable capacity are also used for starting stand-by generator prime movers (see Section 6.4).

• Vented lead-acid batteries

The cells of these batteries are vented, and topping up with distilled water will be necessary at intervals of 3 to 6 months or more frequently in hot conditions. Deterioration and loss of capacity will follow failure to keep the plates covered with electrolyte. The specific gravity of the electrolyte in these batteries should be checked weekly with a hydrometer.

All lead-acid batteries give best service if regularly cycled through normal discharge/charge, and if not subjected either to overcharge (being charged for long periods above the trickle-charge rate) or prolonged discharge (discharged beyond the rated capacity). These batteries should not be left for long in a discharged or partially-discharged condition.

A high-performance version of vented lead-acid cell has Plante plates in which the chemically active material is in paste form contained within perforated hollow electrodes. Cells of Plante


construction can yield lives of up to 25 years, whereas other types of vented lead-acid cells have lives of between a third and a half of this according to type.

• Vented nickel-cadmium batteries

The cells of these batteries are vented, and topping up with distilled water will be necessary at 6 to 12 months intervals or more frequently in hot conditions. Deterioration and loss of capacity will follow failure to ensure that the plates are covered with electrolyte. The specific gravity of the electrolyte in these batteries should be checked monthly with a hydrometer. A useful check on performance is the use of a test instrument comprising a voltmeter mounted on two spikes with which the cell can be contacted to make a discharge through a resistor forming part of the instrument; this on-load voltage test of individual cells will indicate if any cell is deteriorating and should be replaced.

All nickel-cadmium batteries give best service if regularly cycled through normal discharge/charge, and if not subjected either to overcharge (being charged for long periods above the trickle-charge rate) or prolonged discharge (discharged beyond the rated capacity). These batteries will tolerate being left in a discharged or partially-discharged condition provided the plates are covered by the electrolyte. Cells of this kind can yield lives of up to 25 years.

6.3 Battery duration

6.3.1 Nominal duration versus actual duration

The nominal duration of a battery is specified in ampere-hours (Ah) at a specified rate of current discharge (amps). The actual duration of a battery, i.e. its ability to supply its normal designed load for the specified number of hours can be ascertained by discharge/charge testing (see Section 11.1). When such testing shows that the actual duration of the battery has declined to below its specified nominal duration, the battery must be replaced. In the case of large open vented lead-acid cells, cost may be contained by replacing the plates only. In the case of large batteries comprising separate cells, cost may be contained by replacing only the defective cells.


6.3.2 Determining the required nominal duration

BS 52664 recommends that the battery duration of escape lighting for even the smallest premises should be at least 1 hour (plus any period of occupation permitted by the inspector for essential duties to be performed), and that for larger premises a duration of 2 or 3 hours should be specified. Even the 3 hour duration should not be regarded as a maximum for, if no stand-by power is available (see Section 6.4) a greater battery capacity may be justified for reasons of safety. When determining the required battery duration, consider the time it takes to search a large building - especially a multistorey one - to ensure that everyone is out; searching by the subdued illumination of the emergency lighting, possibly in the presence of smoke. Consider what happens when, during the search, an ill or injured person is found on an upper floor; consider the time it takes to descend by the stairs (the lifts being inoperable), to fetch medical aid, to carry the stretcher to the upper floor, render first aid, and then to transport the patient on the stretcher down the stairs to safety. It seems unlikely that the above scenario could be enacted in just 1 hour; and if there were many patients, the time taken to clear all casualties from a high building could be much longer.

The specification of battery duration is thus seen to be an important factor in the specification of emergency lighting equip-ment. It is impracticable to provide much more than a 3-hour duration in the case of self-contained luminaires, and thus a need for greater duration would be a reason for opting for a central battery system. It will always be better to err on the generous side and to specify a 3-hour duration or longer, unless there are provisions for stand-by power supplies for lighting (see Section 6.4) or for mobile lighting (see Section 7.5) which can be quickly brought into use.

6.3.3 New developments in batteries

A considerable amount of research is currently being undertaken to discover combinations of chemicals which will yield improved designs of rechargeable batteries. The search is for batteries with enhanced characteristics such as: lower capital cost, longer life, smaller bulk, lighter weight, faster recharge times, reduced liability to damage from excessive charge or over-discharge. Other objectives are to find


batteries that may be constructed from materials which are less damaging to the environment and easier to dispose of or recycle. Much research seems to be directed to trying to develop batteries for electric cars; however, one new type of battery has been announced which may have some potential value to the development of improved electrical storage for emergency lighting, and this is the nickel hydride (NiH) battery40.

The NiH cell has a high energy density - about twice the capacity of a conventional nickel cadmium (NiCd) of the same weight and volume. It has the disadvantage of high temperature rise at full charge, perhaps requiring a temperature cutout to prevent damage. At the moment NiH cells are more expensive than NiCd cells, but this price difference may change when production of NiH cells increases.

6.4 Stand-by power supplies

6.4.1 Security of power supplies

Mains electricity supplies may be made more secure by taking supplies from two feeders fed from different parts of the supply company's distribution network. It is normal good practice to divide distribution circuits so that lighting loads are separate from power circuits, and adequately protected against overload. Supplies to luminaires in each area of the premises may be fed from two or three phases to minimize the risk of total blackout. Good engineering and maintenance will reduce the risk of breakdown of lighting, but failure may be due to causes beyond the occupier's control, viz, fire, or a failure of the mains supply.

6.4.2 Effects of long outages

Quite apart from emergency conditions due to fire and other dangers which may accompany - or be the cause of - a failure of lighting, a blackout in any workplace can have serious effects; loss of lighting for some hours could not only lose production, it could cause danger because some vital activities cannot be stopped quickly. The cost of such interruptions can be high compared with that for the provision


of stand-by generation to provide power for lighting and essential services during a long mains outage.

Emergency lighting enables persons to escape from premises or from situations of danger during a failure of the normal lighting; it may also enable essential tasks to be continued during a failure of normal lighting, e.g. bringing plant to shut-down, and continuing essential processes to avoid danger or major loss. If such activities are likely to extend beyond the battery duration of the emergency lighting (generally 1 hour or 3 hours), or if a higher illuminance is required for those essential tasks than is provided by normal emergency lighting, then standby lighting may need to be employed.

6.4.3 Stand-by supplies

Self-generation is more costly than buying energy from a power company, but continuous generation can be economic if it is possible to utilize the waste heat from the prime movers (e.g. for steam-raising or environmental heating). However, the cost of having a mains supply to be used only to back up self-generation may be surprisingly high. Despite such considerations, the capital cost of installing generator plant for stand-by use may be justified.

It can be arranged for there to be a bridging battery to provide power for a very short period while the generator is starting up. With suitable controls it is possible to provide an 'uninterruptible' or 'virtually uninterruptible' supply, so that there is no outage during change-over from the normal supply to the stand-by supply (see Section 6.4.4).

6.4.4 No-break supplies

On sites having special processes and dangerous operations, it may be desired to raise the reliability of the power supply for lighting and other essential loads. Equipment of correct design can give a very high degree of protection against interruption111. Some ways of achieving this are briefly summarized in this section.


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Figure 6.2 Rotating-machine system with no-break power supply feature (see Section 6.3.4)

• Rotating-machine no-break power system (Figure 6.2)

This method interposes an electrical rotating-machine between the external supply and the load. On failure of the mains a.c. supply, the d.c. motor takes an alternative supply from the battery, the loss of rotational speed (and hence the loss of frequency of the a.c. output) being minimized by provision of a flywheel to bridge the interval of a second or two while power is being automatically switched to the d.c. motor drive for the alternator. Variations on the theme include:

(a) a 3-unit assembly (alternator, a.c. motor and d.c. motor, all on one shaft);

(b) a dual-wound motor (with a.c. motor and d.c. motor windings) driving an alternator;

(c) units as above in which the d.c. drive doubles as the charging unit for the storage batteries when the mains are healthy.

Any of the above variations can be backed-up with a prime-mover to drive the alternator during outages.

• Virtual no-break standby system (Figure 6.3)

An alternative to using a rotating-machine assembly is for power for the load to be taken as normal from the mains, and for an alternative static power supply to be held in readiness and in frequency


SOLID-STATE SWITCH

a . c . SUPPLY

CHARGER

LOAD

INVERTER

BATTERY

Figure 6.3 Diagram of solid-state 'virtual no-break' stand-by power system (see Section 6.3.4)

synchronism. Change-over by solid-state switching enables the supply gap to be limited to about 0.25 of a cycle, meaning that HID lamps will not be extinguished. On restoration of the supply, switching back is of about the same delay duration, and then the batteries return to charge.

• Solid-state no-break standby system (Figure 6.4)

Such systems employ solid-state switching initiated by a microproces-sor which performs various monitoring and control functions.

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STARTER BATTERY CHARGER

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Figure 6.4 Diagram of 'virtual no-break' system giving a 2-tier standard of reliability. Switches 'Α', 'Β', 'C and 'D' are microprocessor-controlled (see Section 6.3.4)


Typically the battery capacity might be 30 minutes. In normal mode the battery is 'floating', and the output from the static inverter is zero (or is provided with a small dummy load for operational reasons). The modes are:

(a) Normal mode: Switch Ά ' connects main battery charger to mains; Switch Έ ' connects the maintained load to the mains.

(b) Failure mode: Switch Ά ' operates; Switch Έ ' operates to disconnect the maintained load from the normal supply and connect it to the static inverter.

(c) Reversion mode: If normal supply is restored within, say, 1 minute, the microprocessor will bring the static inverter into synchronism with the mains supply before operating Switch Ή ' to reconnect the maintained load to the mains supply, and Switch ' A' operates to reconnect the main battery charger to the mains.

(c) Emergency operation mode: If the normal supply is not restored within a short period, say greater than 1 minute, the microprocessor closes Switch 'C to start the prime mover, monitors the result, repeats if necessary, and opens Switch 'C again on engine start-up. It synchronizes the alternator and static inverter, and operates Switch 'D' to transfer the maintained load to the alternator output.

A series of protective or recovering steps are then carried out according to circumstances. For example, if there is spare generator capacity, it will commence recharging the main battery and starter battery. During the remainder of the outage, the static inverter has zero output but remains in synchronism with the alternator. If the alternator frequency should drop (possibly indicating failure), Switch 'D' will operate, transferring the load back to the static inverter. When mains power is restored, the system reverts to normal mode.

The benefits of such a stand-by power system as described are:

• High reliability. • At every stage the microprocessor will control the system to give

the highest reliability to the maintained load. • Automatic operation, but with the facility for manual intervention

at every stage. • The programme takes account of malfunctions of plant, and will

maintain essential load for as long as possible under all circumstances.


• Minimum size of stand-by battery required. • The microprocessor can monitor parameters such as low fuel for

prime mover, as well as operating annunciators and alarms, and switching lighting.

• Virtual no-break supply enables use of HID lamps.

Under emergency conditions, mobile lighting units having their own generators and intended for outdoor use may be used to provide temporary indoor lighting, and battery-operated handlamps may be of great value under emergency conditions, as may chemiluminescent lights (see Section 7.5).

7 Applications of emergency lighting

7.1 Installations in new and existing buildings

7.1.1 Installations in new buildings

It has long been the lament of lighting engineers that lighting is often one of the last matters to be considered by clients and their architects in the planning of new buildings. In the past this might have been due to the scant education in lighting that architects received during their professional training. But today, with the growth of combined practices (in which experts in lighting and building services engineering are members of the professional design team) there can be no excuse for failure to provide consultation with the client and within the design team.

It is essential to ensure that all aspects of lighting are integral to the building design, and that proper budgetary provision is made for the cost of lighting. Early consultation will enable a number of important design matters relating to emergency lighting to be given proper consideration, including:

• creating opportunities for the integration of lighting architecturally and visually within the building design;

• giving the architect the opportunity to create clear wide escape routes which will add significantly to the safety of the building;

• early consideration can be given to the installation of way-guidance systems or low-mounted floor-flood systems to facilitate escape in smoky conditions (see Section 5.4);

• examining the possibility of specifying luminaires for the general lighting which are 'combined luminaires', viz. which have integral emergency lighting facilities; for example, the 'Sensa' range of fluorescent-lamp luminaires (Figure 7.1) from Thorn Lighting (Appendix A);

Applications of emergency lighting 105

Figure 7.1 Thorn 'Sensa' luminaire which incorporates occupancy sensing and automatic output adjustment, and may be fitted with an integral emergency-lighting feature (Photo: Thorn Lighting) (see Section 7.1.1)

• early consideration of lighting matters will enable emergency luminaires and cable runs to be located in accordance with the guidelines of BS 52664 so as to reduce risk of them being damaged by fire and heat.

7.1.2 Installations in existing buildings

Installations of new, replacement or upgraded emergency lighting are often associated with modifications or upgrading of buildings, and the matter may be in the charge of a building contractor rather than an architect. In any event, it is essential that the installers of the emergency lighting shall be fully familiar with the special require-ments for the electrical installation (see Section 9.1).


• Hazardous zones

There may be serious practical difficulties in upgrading or installing emergency lighting in hazardous zones unless the processes can be stopped, the premises ventilated and a permit-to-work issued when conditions are safe (see Section 7.4).

• Refurbishment and emergency lighting

Refurbishment of emergency lighting may be carried out because the batteries in single-point and combined luminaires are reaching their end of life and must be replaced. Commonly, batteries in such luminaires require early replacement because they have been operated at elevated temperature (see Section 6.2). A method of installing local batteries for single luminaires and groups of luminaires is sometimes adopted in retrofit conversions, with the battery and its charging and detection circuit housed in a separate compartment. If the battery for a single combined luminaire is so housed separately, the battery compartment should be located within 1 m of the luminaire (see Section 4.1). Remote battery compartments should be clearly labelled in accordance with BS 5266*.

It is possible - and sometimes very economical - to carry out retrofit conversion of existing luminaires to emergency use by use of adjacent battery compartments which feed emergency power to the luminaires on mains failure. Any such battery enclosure must comply with the environmental conditions at the point of use (see Section 7.4).

• HID high-bay installations

Some HID (high intensity discharge) lamp luminaires are fitted with a bridging lamp; this is an additional small lamp - usually a low power tungsten-halogen lamp - which is energized when the main HID lamp is switched on. During the lamp run-up period, when the current through the HID lamp reaches a certain proportion of its normal maximum, the bridging lamp automatically extinguishes. The purpose of the bridging lamp is to provide at least some light during the time the HID lamp is running up; thus, if there was a short interruption of the supply, the bridging lamp would operate while the HID lamp was cooling down, restriking, and then running up, thus


avoiding what could be a dangerous period without light. Of course, the bridging lamp as described is not emergency lighting, for when the mains supply fails, it cannot light; but it is possible to provide connections so that in the event of a power failure the bridging lamp can operate from an emergency supply. It is suggested that this idea could be of value in large HID-lamp installations (for example, in aircraft hangars), for the cost of conversion of the luminaires in this way might be less expensive than other means of providing emergency lighting from luminaires at mounting heights of the order of 30 m above floor level.

• Fluorescent-lamp installations

For large fluorescent-lamp installations (e.g. in offices, industrial premises and supermarkets) a method of providing emergency lighting that recommends itself in terms of simplicity and cost is to connect selected lamps within multilamp luminaires to an emergency supply. To overcome problems regarding the operating temperature of the battery if it should be housed within the fluorescent luminaires, separate local battery compartments may be used, or the selected lamps may be connected to a central battery (see Section 3.6.6).

7.2 Exterior locations, stadia, parking areas

7.2.1 Legal responsibilities of occupier

The Fire Precautions Art3, Health & Safety at Work Act1 and other legislation impose duties on occupiers of premises which go beyond the basic common law duty to provide for the reasonable safety of employees and other persons who enter their premises (see Chapter 2). It may not be generally realized that in that context, and in common law, the word 'premises' does not mean only the buildings; it includes also exterior spaces to which employees and other persons have access. Thus, the occupier has a legal duty to provide 'sufficient and suitable' lighting over the whole of his premises, including all outdoor areas accessible to the occupants.

It is sometimes assumed that persons who are in an exterior area are safe; but just getting out into the fresh air is not a guarantee of


safety. Open spaces may have many dangers, including the risks of tripping and falling in inadequate light, or being injured by moving vehicles. When there is a failure of the normal lighting, people escaping from any premises, including outdoor ones, cannot be considered as safe until they reach a 'designated place of safety' (see Section 3.7), and they should be provided with such emergency signs, lighting and way-guidance as are necessary to enable them to get there swiftly and safely.

7.2.2 Outdoor industrial areas

An outdoor industrial area may be a dangerous place; it may for example, contain chemical storage vats or gas cylinders which could cause injury to persons should there be a fire or an accident with a vehicle or a crane. There may be unexpected obstructions, or excavations. Only when suitable lighting for escape is provided will the occupier have discharged his duty to provide for the reasonable safety of persons.

Outdoor lighting installations at industrial premises in the UK rarely provide proper facilities for personnel safety in the event of mains failure. In general, industry does not even provide lighting levels out of doors that meet the minimum recommendations of the CIBSE Code8 for similar tasks performed indoors. Outdoor emergency lighting to facilitate escape is rarely provided, and when it is provided, it may not be fully effective.

It is clearly a matter of great importance to provide sufficient illuminance under mains-failure conditions to enable a person to pick his way safely across an industrial yard cluttered with potentially hazardous obstructions on a dark night. The recommendations of BS 52664 seem to have little relevance to the needs for lighting for escape in many outdoor areas. For example, if a minimum illuminance of emergency lighting illuminance of 0.2 lux is needed to enable a person to find his way along a well defined corridor with a level floor, it is apparent that he would need a rather higher illuminance in order to be able to descend safely in darkness down a series of ladders from a partly constructed building when the normal site lighting has failed.

It has long been the opinion of the author that there is need for a new and more realistic standard for outdoor emergency lighting; in 1980 he first published some proposals for this, having in mind the


special dangers on construction sites, in chemical plants, and in other hazardous outdoor areas. It is hoped that the law will be amended to make it clear to occupiers that they have a duty to provide adequate emergency lighting out of doors. Further, it is hoped that more suitable standards for exterior emergency lighting will be imposed in due course by EC legislation.

While the realistic determination of illuminances for emergency lighting for outdoor workplaces remains a subject upon which lighting experts are not generally agreed, the author offers his own proposals for indoor and outdoor emergency lighting illuminance values which are given in Table 10.1 (see Section 10.1).

7.2.3 Exit route guidance out of doors

Because the visual environment of outdoor places may differ greatly from indoor ones, additional or alternative methods of providing exit route guidance may need to be employed, including the following:

• Pilot lighting

It is recognized that it may be impracticable to apply BS 5266 standards of emergency lighting and signing to very large outdoor industrial areas, and for these it may be necessary to employ other methods. The objective of enabling safe movement when the normal lighting fails at many such locations may be achieved by installing a system of pilot lighting, i.e. a system of strategically placed luminaires, illuminated bollards or signs which would act as direction markers during a failure of normal lighting.

When the normal lighting is not operating, the pilot lighting will enable a person to traverse safely a series of clearly marked straight paths through the site for the purposes of fire/security patrols, or enable him to make his way to an exit or designated place of safety in an emergency. If such pilot lighting systems were supplied from an uninterruptible electrical supply (see Section 6.4), a considerable increase in safety over present practices would be obtained. In hazardous areas, the pilot lighting luminaires must be of suitable protected designs (see Section 7.4).


• Exit signs in outdoor situations

In areas where large numbers of members of the public may be present, the provision of adequate lighting and signing is vital, for many persons present at any time may not be familiar with the layout of the premises. It is thus of great importance that there shall be strategically placed signs to indicate the ways out of any area, with adequate illuminance over open areas and along specific escape routes.

Exit signs, which must comply with Parts 1, 2 or 3 of BS 549912, should be uniform in style, format and colour throughout the premises concerned, and illuminated at all times that the public are on the premises, day and night. While the mounting of exit signs at the conventional height of 2 to 2.5 m is generally satisfactory outdoors, consideration should be given to employing some larger signs and placing them at higher mounting heights (to enable persons to see them from a greater distance when there is a dense crowd), and to employ additional low-mounted signs (which will be visible if the area becomes filled with hot smoke).

• Luminous handrails

It is especially important to ensure there is adequate visibility at stairs and places where there are ramps and changes of level, and the use of way-guidance systems and illuminated handrail systems (see Section 5.4) should be considered, particularly in places where the public may be present in large numbers.

• Illuminated bollards

The normal lighting of open concourses, car-parks etc presents no great problem, for such areas can readily be illuminated by floodlighting; the provision of emergency lighting and escape signing may not be so easy, particularly if one wishes to ensure that there will be adequate light for guidance in the event of the area becoming smokefilled. One method of providing ground illumination and guidance is to employ illuminated bollards (Figures 7.2 and 7.3). Bollards for this duty may be 'self-contained' (fitted with integral emergency batteries, chargers etc), or 'slaves' (supplied from a secure supply fed from a central battery).


Figure 7.2 Bollard fitted with 26- Watt Type PLC compact fluorescent lamp. Operates from normal mains, plus integral 3-hour duration emergency operation from integral nickel-cadmium batteries (Photo: Poselco Ltd) (see Section 7.2.3)

Figure 7.3 Sketch of base-lit bollard for providing directional guidance to vehicles or pedestrians in open spaces. Such a bollard may be fitted with integral batteries to provide 3-hour duration of emergency operation. (Acknowledgement to Forest City) (see Section 7.2.3)


• Way-guidance systems

Where it is desired to provide exit route guidance without obstructing the open area, ground-recessed way-guidance strip systems for outdoor use are feasible. Several systems available now or shortly to be on the market are described as watertight (see Section 5.4). A feature of such strips is their robustness which allows persons to walk on them. Manufacturers state that strips robust enough to withstand the impact and wear of heavy traffic can be made available.

• Ground-recessed direction signs

For some open areas it may be desired to provide brighter sources that can be provided in way-guidance strip form, and ground recessed luminaires may be used (Figure 7.4). Robust enough to stand the weight of vehicles, they would carry the 'broad arrow' direction symbol (see Section 5.2). The upward flow of light from such units will illuminate adjacent buildings etc, and provide orientation.

Figure 7.4 Ground-recessed luminaire of similar construction to the base of a base-lit bollard, but fitted at ground level with a traffic-resistant transparent cover carrying a 'broad arrow' directional symbol. Such a unit may be fitted with integral batteries to provide 3-hour duration of emergency operation. (Acknowledgement to Forest City) (see Section 7.2.3)

• White lining

In designing outdoor escape guidance systems, the value of highly reflective white lines on road surfaces etc should not be overlooked. Proposals have been made to use photoluminescent paints for this purpose, but as far as the author has been able to ascertain such are not yet a practical method. It is understood that the luminance of the


paint is not of a high order, its luminescent period is short (about 20 minutes to half brightness), and the available paints are not durable enough to withstand heavy pedestrian traffic over them even if clear varnished.

7.2.4 Stadia and sports premises

In the design of facilities to provide the means of safe escape during an emergency involving lighting failure under conditions of dense crowding (see Section 3.4) it must be appreciated that when large numbers of people are stimulated by the event they are attending, excitement can rapidly turn to panic in an emergency. Persons in the midst of a large dense crowd have a very limited view of their surroundings, and really can only see upward; to give them direction guidance and reassurance, high-mounted (3 to 10 m high) bright luminous directional signs may be positioned over the escape lanes and concourses.

For clearly defined routes which may be traversed by the public out of doors, CIBSE Lighting Guide LG06 - The outdoor environment23

recommends a minimum illuminance of 0.2 lux along the centreline, and calls for 50 per cent of the route up to 2 m wide to be lit to a minimum of 0.1 lux with a uniformity of 0.025. It is agreed that such illuminances may suffice for moving along a clearly defined, level and unobstructed exit route, particularly if comprehension of one's surroundings has been enhanced by the provision of clean white painted lines; but the recommendation does not take into account the low reflectance factors of typical surroundings, nor take account of the illuminance to which the occupiers' eyes were adapted immediately before the lighting failure. As discussed extensively in other parts of this book, it would take only a whiff of drifting smoke to make an illuminance of 0.2lux quite inadequate.

It is recommended in Lighting Guide LGÖ623 that consultation should take place with the local enforcing authority before the scheme is finalized. This is sound advice, and it would be wise to consult with the insurers as well.

There is rightly considerable public concern about crowd safety, and exceptionally high standards of emergency lighting are justified in situations where a failure of the normal lighting - with or without there being fire or other emergency - might result in an excited crowd


starting to push, or get into a state of panic. By the provision of additional emergency lighting (with illuminances possibly up to 10 lux or more) the possible repetition of tragic events that have occurred in football stadia may be avoided.

7.2.5 Shopping malls

A shopping mall is technically an indoor situation, but its size may justify planning the emergency lighting in a way that would be appropriate to an outdoor location. Shopping malls often have very high glazed ceilings, so that the designer may consider mounting emergency luminaires at heights far higher than conventional heights of 2 to 2.5 m above floor level. If fire occurs, rapid build-up of hot smoke may completely obscure the light from such high-mounted emergency luminaires; indeed, smoke may rapidly prevent daylight from the overhead glazing reaching the pedestrian concourse floor. For this reason it may be necessary to provide emergency lighting in the form of floodlighting from the sides of the public areas, perhaps from just above shop facia height, possibly with floor-level or low-mounted way-guidance as well (see Section 5.4).

7.2.6 Outdoor parking areas

The outdoor areas commonly visited by most people are car-parks. Many motorists will not leave their cars in unlighted car-parks; many women drivers prefer to park in a street (even contrary to any restrictions) rather than use an unlighted car-park. Entering and parking is not the problem; what motorists dread is having to find their way out from the car in the dark. Problems arise when drivers return to a car-park on foot and find it in darkness; once they reach their car again they feel safe, and will have no problem in driving out of the car-park without lighting being provided.

It is an academic point whether what is needed should be termed security lighting1 or emergency lighting. Motorists need lighting to enable them to move safely between the entrance and their car; they also need to be provided with sufficient ambient light to make them confident that they will not be set upon out of the darkness by muggers.


Discussing this problem in a press article, Dodillet and Pears25 cite the requirements of BS 5489: Part 9: Section 326 which calls for normal lighting levels of 50 lux average and 10 lux minimum on the ground in exterior car-parks, and make the point that: Good lighting levels . . . enhance the pedestrian's feeling of personal security and ability to move freely without the threat of being attacked.

The present author has no hesitation in recommending that the minimum standard of emergency lighting illuminance in car-parks should be in accordance with Table 10.1 (see Section 10.1), i.e. an average of 1 lux (or 1 per cent of the normal illuminance if this is greater), with a minimum measured illuminance of 0.2 lux. However, crimes involving cars are increasing year by year, and many assaults and robberies, and stealing of or breaking into cars occur in car-parks; thus far higher illuminances than these may be very well justified. Indeed, in vulnerable situations, the normal car-park lighting should be regarded as 'maintained' emergency lighting, i.e. there should be no diminishment of illuminance on failure of the normal mains supply.

7.3 Areas of special risk

There are locations in which the continuous functioning of the lighting system is essential to prevent the occurrence of a very high probability of injury to persons or the likelihood of some failure or malfunction of plant which could result in significant loss or strategic danger. An example of the latter relates to control rooms for security monitoring (see Section 1.3), for which BS 7499:Part l25 calls for the provision of emergency lighting capable of being brought into operation within 60 seconds of the failure of mains powered illumination, with a duration of at least 4 hours.

Obvious examples of areas of special risk are operating theatres and intensive-care units in hospitals, where it is already standard practice to have 100 per cent back-up of power supplies for the lighting, i.e. interruption of the normal supply will not affect the lighting levels (see Section 3.6.1).

A dangerous condition may arise in some situations if there should be a failure of the lighting but if the supply to plant is not interrupted; the common example is that of machine shops, where a failure of the


lighting which left unguarded machines operating would be hazardous to personnel. One way of dealing with this problem is to arrange that any failure of the supply to the lighting circuits shall trip the supply to other loads; but this may not be acceptable if cutting the supply to other loads would itself produce danger or would result in unacceptable loss. An approach to be considered is that in EC Directive 89/392/EEC13 which legislates for the provision of individual systems of emergency lighting built into or associated with individual machines (see Section 2.6), a provision which is of especial importance in relation to machines which cannot be adequately guarded for operator protection.

Certain potentially hazardous situations can be identified where lighting failure would create especial conditions of danger; these include nuclear laboratories and nuclear materials processing, power stations, and the manufacture of munitions, explosives and fireworks, etc. Of course, not all parts of such premises carry the same risk, but it is suggested that in those areas where the risks consequent on lighting failure are most acute, the stratagem of providing two completely separate systems of emergency lighting should be followed. Alternatively the emergency lighting system shall itself have a back-up system of additional batteries or generating plant (see Section 6.4) to provide a double fail-safe system of emergency lighting.

A working environment which carries a high risk of personal injury is any construction site or civil engineering site. Such sites have a death rate higher than that for deep-sea fishing; and it has long been suspected that many injuries on sites do not find their way into the official statistics because they are suffered by self-employed persons or casual dayworkers and do not get reported. Many sites are operated nominally in daylight hours only, and so the need for emergency lighting is not perceived by the operators - even for the unfenestrated areas of partly built structures, e.g. lift shafts, staircases, basements, tunnels etc. The technical requirements for providing a measure of emergency lighting are not difficult to satisfy; the difficulty is often the reluctance of the site operators to provide even a decent standard of normal lighting for work, let alone emergency lighting1. Emergency lighting from self-contained emergency luminaires could be provided, even on sites having no mains electricity supply. Emergency luminaires can be kept in a good state of charge by a small generator set provided for the purpose, but


switching would have to be provided to prevent the batteries becoming discharged when the generator set was not running - e.g. at night when the site is closed.

7.4 Emergency lighting in hazardous zones

The enclosures of replacement or new emergency lighting equipment for installation in hazardous zones must comply with the require-ments for the zone concerned (see Section 4.1). There may be difficulty in carrying out the work of installing or modifying emergency lighting as it is not permissible to open electrical enclosures or luminaires for maintenance purposes within such zones unless the processes can be stopped, the premises ventilated and a permit-to-work issued by the responsible engineer when conditions are safe.

For applications in areas requiring flameproof, corrosion-resistant, or hoseproof, etc luminaires, the choice of emergency lighting products on the market is limited. The best general solution may be to locate a central battery cubicle in a 'normal atmosphere' zone nearby, and to use slave luminaires having appropriate enclosures in the areas where special environmental protection is required. For general emergency lighting, suitably protected types of bulkhead luminaires may be used.

A review of lighting practice in hazardous and hostile environ-ments is given in the author's Lighting for Industry and Security1. In that book he also outlines proposals for the development of a new kind of universal pressurized type of luminaire which might gain approval for all kinds of rugged, wet and flame-hazardous zones, and which could greatly simplify and cheapen the provision of safe and durable lighting in such zones. It is conceived that emergency lighting equipment constructed on the same principle could be developed.

7.5 Temporary, mobile and portable emergency lighting

7.5.1 Temporary emergency lighting

Where premises are occupied temporarily (for example, during such time that electrical installation contractors are working in otherwise


unoccupied premises) the legal requirement for the provision of 'sufficient and suitable lighting' (including emergency lighting) in workplaces still applies, and may be satisfied by the introduction of a temporary system. In some cases the enforcing authority may permit the temporary use of lamps powered by propane or butane gas; in other cases temporary electric lighting may be employed.

If, for example, work had to be carried out in an area having no mains supply, a number of self-contained illuminated exit signs and luminaires could be brought to the site and fixed temporarily in position, their integral batteries enabling them to operate if personnel are on the premises during the hours of darkness. Control of such luminaires by a local light-sensitive switching device would be possible, and sufficient duration ensured by the provision of additional batteries. Temporary emergency lighting luminaires and signs could be connected to an electrical supply when this becomes available.

To enable work to be carried out in an area having no daylight, portable self-contained lights or handlamps may be used, or a temporary installation of emergency lighting luminaires and signs could be connected to a mains supply if available, with back-up provided temporarily by an external battery and/or generator set mounted on a vehicle or trailer (see Section 7.5.2).

7.5.2 Mobile emergency lighting

Specialist suppliers can provide on hire vehicles or trailers which are equipped with a battery and/or a generator set1. Such mobile power units may be used:

• to provide temporary power from a generator for lighting; • to provide battery back-up power to temporary lighting; • to provide a temporary supply to enable the discharge/recharge

testing of the batteries in emergency lighting systems in premises that are continuously occupied (see Section 11.3).

7.5.3 Portable handlamps and torches

As an aid to dealing with emergency situations during a failure of normal lighting, battery-powered handlamps and torches have their


place. The practical difficulties relating to their use include: • To prevent misuse or theft, battery-powered handlamps and

torches have to be kept in a locked room or cabinet when not in use. Therefore, in an emergency situation there may be delay before they are available where they are needed.

• It may only be discovered that the batteries in torches and handlamps are discharged when there is a need to use them.

These problems may be countered by use of rechargeable handlamps which are normally stowed in a charging rack, from which they cannot be removed until a magnetic lock is released by mains failure or on the operation of a fire-alarm or other emergency circuit.

If portable electric handlamps are used, the following cautions should be observed:

• Personnel should not enter an otherwise dark area which is lit with only one portable handlamp, lest it should fail or be damaged and leave the personnel exposed to danger.

• Handlamps and portable lights containing miniature tubular fluorescent lamps or compact fluorescent lamps which are operated on high-frequency control gear may not be fully screened for radiated radiointerference (see Section 8.2.2), and such handlamps should not be taken into sensitive areas or into proximity with sensitive plant.

• No electrical apparatus of any kind (including battery-operated handlamps) may be taken into any designated hazardous zone unless there is full compliance with the safety requirements for that zone in terms of construction and enclosure of the equipment, and its use (see Section 7.4).

• Under no circumstances should the enclosure of any electrical apparatus be opened in such a zone.

• It is recommended that persons entering potentially dangerous unlit locations and areas into which it is necessary to take portable lighting equipment should also carry one or two chemiluminescent lightsticks (see Section 7.5.4) as a routine precaution.

7.5.4 Chemical lights

Chemiluminescence is the production of light by chemical action. A useful application of this principle is the range of Cyalume®


Figure 7.5 'Cyalume Lightstick'. Bending the stick slightly breaks an inner glass tube which enables two chemical liquids to mix and produce chemiluminescent light (Acknowledgement to Cyanamid of Great Britain) (see Section 7.5.4)


'Lightstick'® chemical lights available from Cyanamid of Great Britain Ltd (Appendix B). These are used for warning purposes in emergencies, and for the safety and comfort of persons trapped in the dark, e.g. entombed miners or tunnellers, or submariners marooned on the ocean bed. The light produced by chemical lightsticks is sufficient to enable emergency work to be done in difficult conditions, including in hazardous atmospheres. Because the devices are small and light in weight they are easily carried in the pocket for emergency use. It is recommended that they should be carried routinely by divers, oil rig workers, and personnel who must enter drains, tunnels, boilers, shafts etc, where a little light could save a life.

As a backup to emergency lighting, these devices may be of great value. In large premises, and especially in multistorey buildings, the availability of these lightsticks could facilitate medical treatment and rescue of injured persons under adverse conditions.

Each chemical light is a sealed plastic tube about 150 mm long and about 12 mm in diameter, which is filled with a liquid. In the liquid there is a small sealed glass tube containing another liquid. To activate the unit, one slightly bends the outer plastic tube by hand, fracturing the inner glass tube (Figure 7.5), thus allowing the two liquids to mix and react chemically so that light is emitted. Development of light output is accelerated by shaking the device and warming it in the hand. No heat is produced and the unit is sealed, so it can be used in the presence of flammable gases and can be operated under water. The chemicals used are non-toxic.

A range of patterns is available, in colours (white, green, orange, red, blue), and various durations and outputs (12 hour, 8 hour, 30-minute Hi-Intensity, and 5-minute Ultra Hi-Intensity).

8 Design considerations

8.1 Consultation

Design of an effective emergency lighting system for a new building or refurbished premises depends greatly on early consultation with the architect and with those providing other building services; for example, the structure should be designed so that the provision of automatic closing fire doors will prevent the spread of smoke and fire into the escape corridors. Too often the provision of adequate escape routes, emergency lighting and fire alarm systems is a matter dealt with late in the building design process - almost as an afterthought.

8.2 Specifications for equipment

8.2.1 Specifications for emergency lighting luminaires etc

Summarizing the requirements very briefly:

• Emergency lighting objectives and requirements - BS 5266 Part l4. • Applications design - for interiors, TM1210 and ICEL:1003n; for

exteriors, LG0623. • Emergency luminaires - construction to BS 453317 Part 101 and

Part 102.22 (see Sections 4.1 and 7.4 regarding enclosures). • Fire safety signs - BS 5499Λ99012. • Emergency lighting located in machinery - EC Directive

89/392EEC13 (see Section 2.6).

8.2.2 Radio-frequency interference (RFI)

Emergency lighting equipment may give rise to radio-frequency interference which can affect sensitive installations such as computers and communication systems.

Design considerations 123

The EC Electromagnetic Compatibility (EMC) Directive28 became UK law from 1 January 1992. The regulations state that equipment complying with the regulations may have the 'CE' mark affixed to it and may be sold throughout the EC without restrictions. The relating specifications are BS 539429 and CISPR-1530.

If emergency lighting equipment is to be installed in premises in which there is sensitive equipment, the specifier should specify his requirements to the emergency lighting supplier. If unshielded emergency lighting equipment may be liable to cause interference, the advice of a specialist supplier may be needed; for example a company such as RFI Shielding Ltd (Appendix B) which specializes in providing screening and interference-suppression materials.

8.2.3 Quality

Purchasers who want to ensure that suppliers can provide emergency lighting equipment that will be of suitable standards of performance, quality and safety, will no doubt give preference to suppliers that are BSI registered firms. Products from such firms may carry the BSI Kitemark Symbol of Quality certifying that the product has been manufactured in accordance with the relevant sections of BS 5750 Quality Assurance.

Suppliers may claim that their emergency lighting products comply with relevant standards, but preference should be given to products bearing the ICEL Certification Scheme symbol which confirms that the luminaire light level and spacing claims have been tested and approved, and that the product meets Kitemark requirements.

8.3 Integrating with other interior lighting

8.3.1 Emergency lighting integrated with normal lighting

The normal lighting of an interior is defined as lighting to aid the safe movement and the performance of normal working tasks by the occupants, and may be augmented with any available natural lighting1. Emergency lighting may be integrated by the operation of selected lamps in the normal lighting system on non-maintained or maintained emergency power circuits (see Section 4.2).


8.3.2 Pilot lighting within buildings

The amount of light needed for patrolling and supervision for security purposes outside of normal working hours will be far less than that needed for normal occupancy activities2, so a system of pilot lighting may be employed for economy and convenience. The system may consist of selected luminaires in the normal lighting system being switched to provide the necessary subdued and economical level of lighting for patrolling and supervision; alternatively, the pilot lighting may consist of a system of small luminaires specially installed for the purpose. A useful safety feature is to have the pilot lighting come on automatically when the normal lighting is switched off during normal working hours; this provides for safety during lunchtimes, tea-breaks, etc, and at the beginning and end of working hours, between shifts, etc.

8.3.3 Integrating interior lighting systems

A typical arrangement for the use of normal lighting, the pilot lighting, and of maintained or non-maintained emergency lighting is shown in Table 8.1.

8.4 Emergency systems and emergency management

8.4.1 Fire prevention by design

Useful references to sources of information on legal and other requirements for emergency lighting are given in CIBSE Technical Memorandum TM1634. Fire precautions should start with correct specification, design and construction of the building31. It can never be good practice to conceive the format for a new building without the fire precautions for it forming an essential part of the brief to the design team (see Section 8.1).

Modern buildings may have sophisticated systems of fire detection, smoke control (motorized smoke curtains, extract fans etc), fire venting devices to prevent build-up of heat (automatic shutters, forced-draft smoke venting), sprinklers, automatic fire doors, etc,


Table 8.1 Use of lighting systems

Normal working hours

Non-working hours, building patrolled

Building closed, not patrolled

Mains failure at any time*

Normal lighting

On

Off

Off

Off

Pilot lighting

Off

On

Off

Off

Non-maintained emergency

lighting

Off

Off

Off

On

Maintained emergency

lighting

On

On

On

On

* It can be arranged that if there should be a failure of the mains supply when the building is not occupied, the emergency lighting circuits will not be activated.

together with computerized monitoring and supervision by a remote monitoring station. Such systems of fire control may be integrated with the security system of the building.

8.4.2 Fire alarms (signals, annunciators)

Systems of audible fire alarms (annunciators, public-address pre-recorded announcements) may be integrated with the emergency lighting system and any system of guidance to enable the premises to be evacuated even in conditions of thick smoke. It should be an objective to evacuate the building swiftly before any smoke present cools and descends, thus making movement along exit routes the more difficult (see Sections 3.3, 4.3 and 5.4).

The automatic transmission of recorded announcements may enable guidance to be given as to the best route out of danger.


Recorded announcements have the advantage that the messages can vary in different parts of the premises; they can also change over the period of time while evacuation is taking place, the message in each part of the premises being tailored according to the nature and progress of the emergency

8.4.3 Fire prevention by safe practices

No matter how well designed the premises are in terms of fire safety, it is only by the performance of safe practices that fire will be prevented. Typical matters requiring attention are:

• ensuring that the emergency lighting system is kept in a state of cleanliness and good repair, and carrying out the required inspection and testing routines (see Section 11.1);

• ensuring that escape corridors and exits are kept unobstructed at all times;

• avoiding unnecessary risks, such as bringing highly flammable substances into the building;

• permitting smoking only in selected areas having minimum fire risk.

8.4.4 Fire detection systems and security monitoring

Fires are sometimes started by intruders maliciously or by carelessness; many fires are deliberately started by persons employed on the premises as a means of concealing shortages of stock or cash. One of the prime functions of security staff and security systems is the early detection of fire.

Because on-site patrols are costly and not always as efficient and reliable as might be hoped, there is a strong trend to take advantage of the capabilities of modern security monitoring systems employing such a high level of software that they are called 'intelligent' systems. Monitoring systems of this kind are usually readily extended to include highly effective means of fire detection, the equipment having the facility to test all its circuits and detectors every few seconds and to give early warning of suspicious conditions which might develop into a fire. If remote monitoring is employed, the


system will submit all alarm messages to a central monitoring station by telephone or packet radio transmission. The central monitoring station can investigate conditions at the protected premises by the use of alternative detection devices and, if a fire or other emergency condition is confirmed, will take all necessary actions including sending for the fire brigade and/or police, despatching a mobile patrol to the premises, and notifying keyholders.

Such systems may be integrated with emergency lighting systems, e.g. the monitoring computer will frequently check for the correct working of all parts of the system including luminaires, wiring, batteries, generator (fuel and lubrication levels etc), and will signal any fault. When an emergency condition is detected, the control circuitry can automatically transmit alarm announcements to the occupants, switch on non-maintained luminaires, start up generator sets etc (and can do this for part or for the whole of the premises), and will keep a record of all events. The system may include an 'event management program' (see Section 8.4.5).

8.4.5 Emergency management systems

An important concept for modern management is the provision of an 'event management program'. This is an analysis of all the possible causes of injury, threat or loss which may occur during the operation of the business, and is usually described by a complex computer-generated algorithm. Based on that analysis, possible preventive or corrective actions are formulated for all the events reviewed, and for combination of events. These actions are ranked in preference modes (cheapest, most effective, quickest to implement, simplest to understand, etc) and then processed by software to produce an event management program, i.e. a rapid means of calculating 'What shall I do if . . . .?' It is then possible to set up a syllabus for training based on such a program, and training formats can be devised for top managers, middle managers, supervisors, rank and file staff, security and fire personnel, etc.

For proper appreciation and implementation for such a complex plan, the training of management grades is the first priority. For a large organization, it is improbable that any one person would have complete knowledge of the whole plan, and would be able to implement all parts of it. This is where a partnership is formed


between the software and the operators, so that when the computer is made aware of a possible cause of injury, threat or loss being present, it will do several things very rapidly: • It will record all the data as it occurs. • Using the probability theory, it will select paths through the

algorithm to discover the best courses of action. • It will signal alarm messages, either general ones like: 'There is a

fire in Department X - and notify all personnel; or specific ones like: 'An attempt is being made to force Door No. 126, Ground Floor' - and notify the appropriate security personnel.

• It will implement a series of specific actions without any management intervention (e.g. broadcasting fire alarm messages, switching on lighting, starting generators), and then will present a series of screen menus for management decisions. If no decisions are made within a timed period, the program may go ahead and take certain emergency actions for the control of safety, threat or loss (e.g. send for fire brigade, transmit recorded message to the police).

It will be seen that a computer driven event management program may be a powerful ally in any emergency; but for full effectiveness, the following are necessary: • The program should be seen as advising, not commanding, for it

can be overridden at any time by a responsible person. • All personnel affected must understand that instituting such a

program does not relieve any person in the organization from the duty of acting responsibly and doing what is necessary to deal with the situation.

• All grades of personnel must be properly trained and have an appreciation of the outline of the whole event management program, and must be trained so they understand the specific duties which are required of them in an emergency.

It will be seen that even a simple event management program which can be written on a single sheet of paper would be better than people having to make hasty decisions in an emergency when they might not be sure of what options are open to their choice. The provision of emergency lighting should be seen as a component of the event management resources of the organization devoted to the objectives of reducing the risk of injury, threat or loss.


8.4.6 Fire alarm call points

Although automatic fire detection is of great value in detecting fire in unoccupied premises, in practice some 70 per cent of fires in business premises occur when the premises are occupied. Fire-alarm call points are thus seen to be of great importance, and the question must be asked: should not every fire-alarm call point be fitted with an integral light operating from a maintained emergency power supply?

8.4.7 Internal smoke control doors

An internal door which is intended to prevent the spread of smoke in a building will usually be fitted with a self-closing device. Such a door may be considered to impede the free movement of persons, and for this reason it may be provided with a magnetic device to hold it in the open position during ordinary use of the building. On the activation of the fire alarm system, the magnetic device is automatically de-energized, permitting the door to close under the influence of its self-closing device.

It is recommended that internal smoke control doors shall be fitted with a toughened-glass window so that an escaper approaching the door after it has closed can see through it. There should be an illuminated ΈΧΙΤ' sign above the door. The 'EXIT sign or an emergency lighting luminaire located within 1 to 2 m of the door on the approach side should illuminate a notice on the door stating:

This door is fitted with a self-closing device

which will allow it to close automatically in emergency.

PUSH TO OPEN

An emergency lighting luminaire should be located on the exit side of such a smoke door, positioned so that it is visible through the door glass panel from the interior side of the door.


8.4.8 Final exit doors

Final exit doors are usually fitted with 'panic bar' locks to ensure that they can be easily opened from within. The usual TUSH TO OPEN' notice on the interior should be well illuminated by an adjacent emergency lighting luminaire.

Because final exit doors present a security risk, they are usually locked when the building is not occupied. This is a potentially dangerous practice; someone forgot to unlock the final exit doors at a retail store some years ago, and several women trying to escape from a fire perished on the wrong side of the toughened glass final exit doors while would-be rescuers looked on helplessly. A safer practice is the use of spring-loaded bolts which are held in the locked position by magnetic coils; the coils are de-energized and automatically release the bolts on the activation of an emergency alarm circuit or on mains failure.

The need for exterior lighting to enable escapers to move safely from the final exit door to the designated place of safety has been explained (see Section 3.7). Final exit doors should be identified externally with a bold sign:

FIRE EXIT KEEP CLEAR

The exterior emergency lighting should be arranged to ensure that the door, its notice and its step are well illuminated. Bollards may be used to prevent vehicles parking so close to the final exit doors that their opening and the movement of persons leaving by them would be impeded (Figure 8.1).

8.5 Access to luminaires

Inconvenience of access tends to lead to neglect to clean luminaires and signs, and to neglect of routine testing if remote means of testing


Figure 8.1 A final exit door leading out into public space (see Section 8.4.2)

(see Section 11.1) are not provided. Because emergency lighting luminaires and signs in ordinary industrial and commercial installa-tions rarely have to be mounted much higher than 2 or 2.5 m above floor level, access is not generally a problem; however the following points should be noted:

• Luminaires on staircases

Locations for luminaires are usually chosen by the design engineer who has in mind the distribution of light rather than the convenience of the person who must later service the equipment. It is common to see luminaires located on staircases where, although they are only nominally 2 m above the plane or incline being lit, are in fact located at positions where it is virtually impossible to gain access by single ladder, and two ladders and a plank must be used.

• Large open areas

Access to overhead emergency lighting luminaires in open areas such as machine shops, large sales areas in departmental stores and


supermarkets may be impeded by temporary or permanent obstructions such as machine tools in factories, and displays and 'gondolas' in retail premises. Locating the overhead luminaires between permanent obstructions will facilitate access for mainte-nance. Access may be gained by using two ladders and a plank. For large premises, access platforms of various patterns are available1.

• Stadia

In discussing the provision of emergency lighting over seating areas in stadia (see Section 7-2) it is seen that the luminaires may have to be mounted on the soffit of the roof structure of a stand, so that luminaires may be 6 m or higher above the plane or incline being illuminated. Access is made more difficult by the presence of permanently installed seating and/or ramps or slopes. In such situations access to the overhead luminaires might be better achieved by walkways or through the roof1.

• Dirty areas

In industrial areas where there is a considerable degree of atmospheric pollution, routine and frequent cleaning of luminaires may be carried by use of a high-pressure water jet.

Warning: To prevent what could be tragic accidents, hosing of luminaires should only be practised if ALL the luminaires and electrical fitments in the area concerned are of 'water jet proof construction17.

9 Electrical installations for emergency lighting

9.1 Reliability and safety

While competent installers will work generally in accordance with the latest edition of the IEE Wiring Regulations24, it is recommended that Section 8 of BS 5266:Part l4 be specifically drawn to the attention of installers of emergency lighting, as those not experienced in this work may not be fully aware of important matters affecting safety and reliability of wiring systems and circuits which are dealt with in that standard.

It is vital that the installation of emergency lighting and signs should not itself be a cause of danger of fire or electrical fault, and the following points should be noted:

• Luminaires are normally designed to operate in a maximum ambient temperature of 25 °C. If ambient temperatures higher than this are likely, advise the manufacturer who may be able to offer suitable equipment for the duty.

• Luminaires may be mounted on normal flammable surfaces (e.g. wooden partitions) if they are T'-marked to BS 453317.

• Note that surge suppressors may be required at the point of connection to the supply wiring if mineral-insulated metal-sheathed cable is employed. If control gear for fluorescent lamps is located remote from the luminaire and is connected by mineral-insulated metal-sheathed cable, seek the lighting manu-facturer's advice as to the maximum distance permitted between the lamp and the control gear.

9.2 Defective installations

It would seem that there is need for a general improvement in standards of wiring, particularly in industrial premises. Over a period


of years, the author has noted the following bad practices in emergency lighting installations:

• Wiring to a self-contained exit sign connected by a long unsupported loop of flexible insulated cable, not of high fire-resistant grade, not in conduit nor otherwise mechanically protected, and vulnerable to damage.

• Surface wiring to emergency luminaires routed immediately above an opening where it was likely to be struck by high loads on forklift trucks passing through. This cabling was in plastic snap-lid trunking, which was not of a fire-resistant grade.

• In an emergency lighting wiring installation in a factory, an unlabelled joint-box.

• At a school, unlabelled switchgear in a plant room containing a central battery. The room was not ventilated.

9.3 Connecting to an external power source

In premises which are continuously occupied (e.g. airports, hospitals, continuously-operating chemical plants) arrangements may have to be made to connect an external mobile power source to the emergency lighting system to permit periodic discharge and charging cycles to be carried out on the batteries as are required by BS 52664

(see Section 11.3).

9.3.1 Central batteries

Connection of an external power source may be made by providing switching and connection means which form part of the permanent installation. For example, at a point where it would be safe and convenient to temporarily locate a battery/generator trailer or vehicle, means of connection should be provided to enable the installed central battery to be isolated from the distribution system which feeds the slave luminaires. The central battery can then be tested and conditioned by a discharge/recharge cycle. If a mains power failure should occur during the testing cycle, the external power supply takes over its duty and will provide power to the slave luminaires for the duration specified in the Fire Certificate.

Electrical installations for emergency lighting 135

9.3.2 Batteries in self-contained luminaires.

• Luminaires having common supply connection

If all self-contained emergency luminaires in an installation are connected to the mains via a common dedicated connection board, it would be possible to arrange for an external mobile power source to be connected at that connection board. The self-contained emergency luminaires can then be put through their discharge/recharge cycle. If there should be a failure of the mains supply during the test cycle, the external power supply would take over the duty and maintain the output of the luminaires for the required duration.

• Luminaires not having common supply connection

If the mains power supplies to the self-contained emergency luminaires and signs in an installation are not fed through a common dedicated connection board, it may be necessary to bring an external battery to each emergency unit. With suitable connection means and circuitry provided in the self-contained emergency luminaires and signs, it is possible to plug in an external battery at each unit.

It can be arranged that plugging-in the external battery isolates the integral battery from the mains, so that it may be discharged by illuminating the lamps in the unit. After a successful test and recharge of the integral battery, removal of the external battery connection restores the unit to normal condition. If a mains failure should occur during the testing cycle, the temporary external battery will power the lamp(s) in the luminaire or sign for the required duration.

• Hazardous zones

It is important to note that above procedures can only be followed in normal environments. In hazardous zones (see Section 7.4), no electrical connections may be made except through approved types of connectors suitable for the hazard, nor may non-protected electrical equipment of any kind be introduced into the zone.

In hazardous zones which are continuously hazardous and continuously occupied, safe testing of the installed emergency lighting system would be possible if the luminaires in the installation are connected to the mains via a common dedicated connection


board; it would then be possible to arrange for an external mobile power source to be connected at that connection board, such connection being made in a non-hazardous zone.

If the mains power supply to the self-contained emergency luminaires and signs in such a hazardous zone are not fed through a common dedicated connection board, it may be necessary to bring an external battery to each emergency unit, but only if this can be achieved within the constraints of safety regulations for the zone. Alternatively, portable self-contained emergency luminaires and signs may be used during the testing cycle of the installed units, these being in enclosures appropriate to the zone (see Section 10.5).

10 Illuminances for emergency lighting

10.1 Specifications and recommendations

10.1.1 Response time

BS 52664 stipulates that, on failure of the normal lighting, the response time of the emergency lighting (time to start operating) shall be not more than 5 seconds, though this period may be extended to 15 seconds (at the discretion of the enforcing authority) if the premises are likely to be occupied for the most part by persons who are familiar to them. This proviso is of little practical value, and relates to systems where the emergency lighting is provided from generators which take an appreciable number of seconds to come into operation. The idea is a bad one, for it would be far preferable for installations powered by generators to have a bridging-battery to operate the lighting between the time of mains failure and the availability of power from the generator (see Section 6.4) so that there is no discernible delay in the emergency lighting taking over.

Experience suggests that, in locations such as machine shops, those first seconds immediately following lighting failure are a time of greatest danger of persons having tripping and falling accidents or colliding with objects etc, and especially if the lights should fail and potentially dangerous machines continue to function. Clearly, the best arrangement will always be for the emergency lighting to come on within a fraction of a second of failure of the normal lighting.

It is understood that it may be the intention of the LGL/24 committee to introduce in a future version of the standard a provision to reduce the permitted delay to 2 seconds maximum, and to allow up to 10 seconds for the emergency lighting to come up to full light output. It can only be commented that if there must be a delay at all, it should be as brief as technology can make it. Every second of delay in the provision of the emergency lighting illuminance on the failure


of the normal lighting tends to increase the fear and anxiety of the subject, and this has a deleterious effect upon his vision in those first vital seconds when his prompt response may greatly affect his chance of survival in an emergency situation (see Section 3.1.4).

10.1.2 Emergency illuminance

BS 52664 lays down the illuminances that shall be provided on escape routes. These are very small indeed, just about the same as full moonlight. They are defined as 0.2 lux minimum along the centrelines of escape routes, with a maximum diversity of 0.025 (40:1); and for 'undefined escape routes', i.e. open areas, without a defined escape path, the standard requires that the whole area should be illuminated to not less than 1 lux average, which (applying the 40:1 ratio) means that these areas could have a minimum illuminance of 0.025 lux.

Such requirements can readily be achieved in small rooms -perhaps by a single luminaire which doubles as an illuminated exit sign as well. Applied to office blocks and cellular offices and corridors, the standard works well enough; but, applied to larger industrial premises which may present a variety of hazards to the escaper, many people have serious doubts as to the adequacy of the recommendations.

Doubts about the adequacy of the 0.2 lux figure stem from experience of the great diminution of illuminance that occurs in the presence of even a little smoke, or because of dust suspended in the air following an explosion. Further, our eyes take an appreciable time to adapt to such a low illuminance following exposure to typical illuminances in the range of 200 to 700 lux of general lighting, or perhaps far higher under local lighting.

In an emergency, the occupants may be frightened, and their adrenalin reaction will result in their pupils dilating, making their eyes more susceptible to glare, and this is likely to delay their adjustment to a very much lower illuminance (see Section 3.1.4). Table 10.1 shows the author's proposals for illuminances for use in interior and exterior emergency lighting systems.

Under emergency conditions, the expectation of achieving safety by the provision of a minute illuminance along the centreline of a

Il luminances for emergency l ighting 139

Table 10.1 Illuminances for indoor and outdoor emergency lighting

Activity Standard design MMI* illuminance (lux) (lux)

Escape along safe and known routes; emergency exit lanes, or walkways and paths where the users are familiar with them or the route is level and not dangerous to traverse

Escape along dangerous or unknown routes;

emergency exit lanes, walkways and paths where the users are not familiar with them or the route is uneven or possibly dangerous to traverse, and involves risk of falls, contact with hot or sharp objects, etc

1 or 1% of the normal illuminance (which-ever is the greater)

or 5% of the normal illuminance (which-ever is the greater)

0.2

* For each of the standard design illuminance values given in Table 10.1 (which are average illuminances over space and time) a minimum measured illuminance (MMI) is given, this being the actual minimum illuminance anywhere on the ground in the lighted area as confirmed with a lightmeter.

theoretical escape route (which may now be cluttered with unfamiliar obstructions) is a somewhat unreal concept. Current thinking on this matter of obstruction of escape route is that the 0.2 lux figure will suffice if the escape route is uncluttered with any obstructions; but that if there is the likelihood of there being unfamiliar obstructions the figure should be raised to 1 lux. It is even being debated whether a trolley, being pushed by an operative at the instant the lights fail, is an obstruction or not, and the view has been seriously put forward that the trolley only becomes an obstruction if the operative lets go of it. It would seem that the enforcing officer is the final arbiter on this matter of illuminance; he may decree that if the escape route is likely

5 1


to be unobstructed at all times, 0.2 lux will suffice; but if it is likely to be obstructed, 1.0 lux must be provided.

Such nonsensical arguments recall the crude experimentation which helped the compilers of the 1975 version of BS 5266 decide that 0.2 lux would be sufficient to provide for safe movement. It is understood that they experimented in a windowless corridor, dimming the lighting little by little to determine the lowest illuminance that would enable them to avoid tripping over a series of cardboard boxes scattered at random positions along the corridor. The experiments were not conducted with accurate photometric controls; we do not know the reflection factors of the floor or walls in that corridor, nor indeed of the cardboard boxes; no one assessed the glare effect from the luminaires that happened to be there; there is no record of the ages of the experimenters, nor do we know the condition of their eyesight. When they performed these classic experiments, they were not in a hurry, and their speed of escape was not timed; they were thoroughly familiar with their surroundings, and knew that they were not in any danger; if they had tripped they would only have fallen on to a softly carpeted floor; there was no smoke; they had all the time in the world to adapt to the low illuminance, and were not suddenly and unexpectedly plunged into virtual darkness and frightened - as real people are in real situations.

The author has done some experiments too. It has to be admitted that his tests also were somewhat crude, but they were very revealing. What he discovered was the rather obvious fact that the higher the normal illuminance at the time of failure, the longer it takes our eyes to adapt to a low emergency lighting level. He used a test card having white letters on a black background, with letters 10 mm high. He experimented to find out how long after failure of the normal lighting it took for a subject's eyes to adapt to 0.2 lux and be able to read the test card at a distance of 1.5 m in an illuminance of 0.2 lux. He found that if the normal lighting was of the order of 700 lux, it could take up to 1 minute 45 seconds for an elderly person to adapt sufficiently to read the test card. This led him to the conviction that an emergency lighting illuminance should have a definite relationship to the level of the normal lighting - a concept he expresses in his recommendations given in Table 10.2.

Another factor that appears not to be sufficiently taken into account in the specification of illuminances for emergency lighting is the nature of the environment and the floor or ground surfaces over

Illuminances for emergency lighting 141

which escapers must traverse to reach the designated place of safety. There is a world of difference between walking along a straight, level, carpeted corridor in the Festival Hall, and making your way across a densely cluttered, uneven and roughly-surfaced yard at a foundry in the middle of the night. Therefore, it is the author's belief that emergency lighting illuminances should take into account the nature of the escape path and its dangers. Being unfamiliar with the surroundings also adds to one's dangers and increases the fear and apprehension - again leading to diminution of one's powers of seeing (Section 3.1.4). This effect is again taken into account in the author's recommendations given in Table 10.1.

Another factor in finding the way along an escape route is the ability to orientate oneself. One cannot walk anywhere without some idea of the direction one needs to head for. This is why - especially in outdoor locations - the concept of 'pilot lighting' is so important (see Section 7.2.5). It must always be remembered that smoke may prevent the escapers seeing that life-saving exit sign, even if it is only a few metres away. As is clearly demonstrated by the theoretical study demonstrated in Table 3.1 (see Section 3.4), in smokefilled conditions, overhead emergency lighting and exit signs are useless, and only a low-level lighting system or a low-level way-guidance system will enable persons to orientate themselves and move towards safety (see Sections 4.3, 5.4 and 7.2).

Notwithstanding the recommendations in Table 10.1, it will always be sound practice to position an emergency luminaire within 2 m of any specific hazard. And, if the hazard is particularly potent (e.g. a hot furnace or retort, with which even brief contact could cause serious injury), it would be better practice to locate two emergency luminaires within 2 m of the hazard. For locations where the risk of personal injury is high, it would be sound practice to increase the emergency illuminance to 10 per cent of the normal illuminance. It is clearly good practice to ensure that any stairway forming part of an emergency escape route (as well as stepped terraces in stadia) shall have an illuminance of at least 1 lux - and preferably 2 lux on every step.

10.1.3 The duty of care

The legal responsibilities of occupiers of premises in regard to emergency lighting are reviewed in Chapter 2. It is tempting to


assume that providing an emergency lighting system that complied with BS 52664 would make the occupier immune to claims for damages and charges of negligence in respect of his duty to provide 'sufficient and suitable' lighting should an injury or death occur, but this is not so; compliance with a British Standard does not in itself confer immunity from legal obligation. If it is judged that a higher standard of illuminance, or a different method of lighting, would better discharge the duty of care that all occupiers have towards persons on their premises, then that higher standard or different method should be adopted.

10.2 Illuminance measurements

10.2.1 The need for measurements

Manufacturers of emergency lighting luminaires will be concerned with photometric measurements as described in BS 5225 Part 335. Such measurements enable the derivation of lighting scheme planning data, and normally will not be the concern of designers, installers, maintainers and users of emergency lighting installations.

To measure illuminance produced by emergency lighting lumi-naires in actual installations, the guidelines given in TM1210 should be followed. Installers of emergency lighting will need to carry out photometric measurements in installations to confirm that the illuminances produced satisfy the requirements of BS 52664 as interpreted by TM1210 and ICEL:1003n. Maintainers and users of emergency lighting may need to make photometric checks on the performance of installations, for example, to detect need for cleaning, relamping or other correction to bring the actual illuminance up to the specified level.

10.2.2 Lightmeters

Illuminance may be measured with a portable instrument called a lightmeter (also called a luxmeter or portable photometer). The light-cell of the instrument is held in the plane of measurement, and the illuminance in lux read from the scale. It is important to note that a lightmeter indicates the illuminance at the point of measurement,


not the average illuminance in the space. If one wishes to measure the illuminance on the floor, the cell must be placed on the floor.

Lightmeters in common use have ranges of 10 lux to 5000 lux full scale deflection and are not sensitive enough to measure the low illuminances used in emergency lighting. Lightmeters reading to much lower levels (e.g. with scales as low as 1 lux, 2 lux or 5 lux full scale deflection) are available for measuring emergency lighting and exterior lighting. Lightmeters are covered by BS 66736.

It is recommended that a suitable low-reading Hghtmeter be held available in every premises where emergency lighting is installed. Its use enables existing lighting to be measured and compared with the recommendations of BS 52664, and enables the user to ascertain if cleaning, relamping or upgrading of the installation is necessary.

Many available lightmeters are bulky and easily damaged in practical use. An instrument which has been developed specifically for the emergency lighting application is the Menvier Hghtmeter which is a robust, laboratory-standard instrument designed for continuous field use (Figure 10.1).

Figure 10.1 Lightmeter for measuring illuminances in the range employed in emergency lighting (Photo: Menvier (Electronic Engineers) Ltd) (see Section 10.2.2)


10.2.3 Care and use of lightmeters

Avoid subjecting a lightmeter to excessive vibration or shock. Do not allow it to become hot, e.g. do not leave it on a radiator or in direct sunshine. Take care not to expose the cell to overbright sources, e.g. exposing it to an illuminance that drives the needle beyond the scale limit or drives a digital indicator to overload; such use can permanently damage the cell. Keep the lightmeter in its case when not in use.

Do not shade the cell with your body when taking readings. For accuracy it may be necessary to repeat readings at a point, but with the operator standing in a different position relative to the cell. If the lightmeter is fitted with a pointer-lock, this may be used to take readings in difficult situations where the operator would shadow the cell if attempting to read it; place the cell at the point of measurement, stand as clear as possible and apply the lock, then take the instrument from that position and read the indication. Follow the manufacturer's instructions as to whether the pointer-lock shall be applied when the instrument is stored or carried about.

Shading of the cell by the operator's body can be avoided by use of a 'wand' (Figure 10.2), which provides a convenient way of taking a succession of readings at floor level without fatigue.

Before using a lightmeter that has not been in use for weeks, expose the cell for ten minutes or so to an illuminance that moves the

SHAFT, IN THREE SECTIONS WHICH SCREW TOGETHER

COSINE-CORRECTED PHOTOCELL

Figure 10.2 Wand to hold separate photocell of lightmeter in position without shadowing it with the operator's body. It provides a convenient means of taking a succession of floor-level illuminance readings without fatigue (Acknowledgement to Belvoir Lighting Consultancy) (see Section 10.2.3)


pointer or digital indicator to about the centre of the scale; then subject it to several swings of up to full scale deflection by facing the cell to a suitable light source, taking care not to expose it to a greater illuminance than that catered for by that scale.

If a scale-change switch is fitted, note that high-resistance in its contacts can cause inaccuracy of readings. To check, cover the cell (for zero reading), and move the scale-change switch between all its settings several times; then uncover the cell and take readings in a position where the measured illuminance can be read on either of two scales, and compare the readings. If scale change is obtained by placing a mask over the cell, the latter test can similarly be performed by making measurements with and without the scale-change mask. If the cell is remote from the instrument, take care not to reverse the polarity when connecting.

10.2.4 Lightmeter suppliers in UK

Some suppliers of lightmeters located in the UK: Belvoir Lighting Consultancy, Applegarth, Burton Lane, Whatton-in-the-Vale, Nottingham, NG13 9EQ. Tel/Fax: 0949 50660.

GEC Alsthom Protection and Control Ltd, St Leonards Works, Stafford, ST17 4LX. Tel:0785 223251; Fax:0785 212232.

Megatron Ltd, 165 Marlborough Road, London, N19 4NE. Tel:071 272 3739; Fax:071 272 5975. Menvier (Electronic Engineers) Ltd, Southam Road, Banbury, Oxon, OX16 7RX. Tel:0295 256363; Fax:0295 270102.

Minolta (UK) Ltd, Tanners Drive, Blakelands North, Milton Keynes MK14 5BU. Tel:0908 211211; Fax:0908 613497. Permic Emergency Lighting Ltd, PO Box 3, Chesterfield, Derbyshire S40 1EX. Tel:0246 270914; Fax:0246 275879.

11 Testing and servicing

11.1 Routine functional testing

BS 52664 calls for daily inspections, and for monthly, six-monthly, three-yearly and subsequent annual inspections and tests.

11.1.1 Daily inspection

This requires the inspector to check that any previously reported fault has been dealt with, and that the lamps in maintained systems are operating; he is required to check that indicator lamps on self-contained luminaires indicate mains healthy ('on charge'), and that the panels on central battery and generator plant are indicating normal operation. Any faults should be noted in the log book for action.

This simple procedure is often honoured in the breach. In the case of small installations, it hardly seems worthwhile for someone to take the trouble to walk round the emergency luminaires every day; and at large premises the maintenance staff always seem to be too busy to visit every part of the works daily for a duty that appears to lack urgency.

Some organizations make departmental managers responsible for checking of the emergency luminaires and signs in their own departments daily, inspection of the central plant being carried out by the maintenance staff.

11.1.2 Periodic inspections and tests

These tests are intended to discover any actual or incipient faults in lamps, luminaires, the distribution system, batteries and generators. Batteries are given a brief check by causing them to supply the lamps by simulated mains failure. Briefly summarizing the required procedures:

Testing and servicing 147

• Monthly

The batteries of self-contained luminaires and signs are to be tested only for long enough to check that the lamps light, and the period of simulated failure of the mains supply should not exceed 25 per cent of the rated battery duration. Engine-driven generators are to be operated to supply the lamps for at least 1 hour.

• Six-monthly

Each 3-hour duration self-contained luminaire is to be energized from its battery for 1 hour, and 1-hour duration units are to be operated for not more than 15 minutes. Engine-drive generators are to be operated to supply the lamps for at least 1 hour.

• Three-yearly

The batteries of self-contained luminaires and signs are to be tested for their full duration.

• Subsequent years

After the first 3-yearly test, a similar test should be carried out annually on self-contained luminaires which have sealed batteries.

The task of carrying out tests of the duration of both central batteries and the batteries in self-contained units may be simplified by employing pulse-coded infra-red transmitter testing devices (see Section 11.2.1). Systems of automatic self-testing are available for both central batteries and those in self-contained units (see Section 11.2.2). In the latter case, although the automatic testing returns a 'no fault' diagnosis, it is vital that the lighting units are actually visited and inspected for signs of lamp blackening, damage or the need for cleaning which cannot be detected remotely.

11.1.3 Routine care

Routine care of emergency lighting luminaires and internally-illuminated exit signs should be coupled with the periodic inspections, and the opportunity taken to clean the luminaires and to


replace any blackened or failed lamps. In hazardous zones it will not be possible to open the enclosures while the plant is operating and a flame hazard exists, but when the opportunity occurs luminaires should be cleaned internally and externally. In very dirty areas, rather than to attempt to clean the luminaires, it may be more practical to swap the installed luminaires for serviced and clean ones; to enable this to be done, it will be necessary for the enforcing authority to permit the disconnection and reconnection of the units by means of approved plugs and sockets.

The importance of being able to obtain easy access to the equipment is stressed (see Section 8.5). In one factory visited by the author, the maintenance engineer was provided with a trolley for carrying spares and cleaning materials, the trolley being fitted with a short ladder to enable luminaires mounted at up to 2.5 m above the floor to be reached with ease.

To facilitate the efficient performance of all routine testing and care of the emergency lighting system in large installations, it is suggested that the user should devise his own specific schedule of work based on Section 12 of BS 52664, so that the luminaires in each section of the premises are visited in turn and given any necessary attention. To this end, a site plan, with identifying numbers allotted to each item of equipment will simplify the procedure. It may be convenient for the identifying number to be displayed on or near each luminaire and illuminated sign, so that members of the staff can phone in to the maintenance department to report any faults seen.

11.2 Tests of battery capacity

Batteries, both those in self-contained units and central batteries, must be tested as set out in BS 52664 (see Section 11.1). The tests of battery capacity by discharge and recharge have the effect of conditioning the cells and help to extend their life (see Section 6.2) as well as confirming their fitness to remain in service. The method of initiating a test is to interrupt the mains supply to the charger, thereby simulating mains failure.

For battery discharge tests to be meaningful, it is essential that the discharge period is carefully timed - a procedure which is itself time-consuming and difficult when there is a large number of


self-contained units to be tested. Even if it is possible to simulate the mains failure for a whole group of luminaires very easily (because they are on the same distribution circuit), someone has to be present towards the end of the 1-hour or 3-hour test period to note the results and to initiate any corrective actions that are required.

Methods of testing which are available include hand-held infra-red transmitters (see Section 11.2.1) and automatic self-testing (see Section 11.2.2).

11.2.1 Infra-red testing devices for self-contained units

Some manufacturers provide a convenient means of simulating mains failure for testing self-contained emergency luminaires and illumin-ated signs by the use of a hand-held coded infra-red transmitter. When the test is initiated, a timing device operates, so the test is in effect a 'go/no-go' test, and it is not necessary for a person to be present while the tests are in progress.

Figure 11.1 'Flashpoint IR' hand-held transmitter unit for initiating and controlling testing of battery duration of self-contained emergency lighting luminaires (Photo: Ring Electronics Ltd) (see Section 11.2.1)


An example of such a testing method is the 'Flashpoint IR'® system from Ring Electronics Ltd (Appendix A) (Figure 11.1) which can be used for testing luminaires indoors and outdoors. Two alternative transmitters are employed for 1-hour and 3-hour duration units. Each luminaire displays two LEDs; a red one designated the 'test monitor' and a green one designated the 'charge monitor'. The hand-held transmitter has colour-coded press-buttons to (a) initiate a 1-hour or 3-hour battery test, (b) terminate a test and reset the system, or (c) set a luminaire in non-maintained mode. In the Ring Electronics system:

• Green LED (Test Monitor): when on it signifies that the luminaire passed the last test performed on it. If it is off, it indicates that the luminaire failed its last test, or that it had not been reset after installation or after a prolonged mains failure. Failure of the green LED to come on after a test could indicate a fault requiring investigation.

• Red LED (Battery Charge Monitor): when on it indicates that the battery is being charged. When off it signifies either (a) mains failed, (b) the unit is under test (i.e. it is under simulated mains failure) or (c) there is a fault requiring investigation.

11.2.2 Automatic self-testing of batteries

Emergency lighting equipment and installations can be supervised and routinely tested automatically to the requirements of BS 52664 by electronic monitoring which may or may not be part of an integrated computer system relating to security and the control of building services systems (see Section 8.4). Examples of systems providing automatic monitoring and self-testing of batteries are those offered by ABB Control Ltd (Appendix A) (Figure 11.2), and by Protect Fire Detection pic (Appendix A).

The Protec system provides a self-testing system for central-battery emergency lighting systems without the need for additional wiring for test circuitry. The controller stores information and produces print-outs of events when required. The central battery testing method is a development of the Protec automatic testing facility for self-contained emergency lighting luminaires. It has the feature that if the normal lighting were to fail in some zones but not in others, the emergency lighting would be switched-on only in the zones affected, so saving battery power.


Figure 11.2 A 220 Va.c./d. c. central battery system for emergency lighting providing fully automatic supervision of function and battery duration tests, which is claimed to greatly reduce maintenance costs (Photo: ABB Control Ltd) (see Section 11.2.2)

11.3 Battery testing in continuously occupied areas

Batteries in all emergency lighting systems must be periodically tested and conditioned by being put through their periodic discharge/charge cycles (see Sections 6.2 and 11.1).

BS 52664 calls for operational testing of emergency lighting batteries, both for central battery systems and for batteries in self-contained units (see Section 11.1). The standard does not explain how testing of battery capacity (see Section 11.2) can be arranged in continuously occupied buildings such as airports, hospitals, power stations etc.


If the battery should be partially discharged and thus be unable to deliver the duration specified in the Fire Certificate, then in order to follow the law scrupulously the building should be evacuated and remain unoccupied until the batteries have been adequately recharged. During daylight hours, in buildings which are adequately fenestrated, this seems anomalous, for failure of the normal lighting would not impede the escape of persons even if the emergency lighting was not functioning. However, in the presence of dense smoke, the proper functioning of any low-level way-guidance system (see Section 5.4) would be vital.

In the opinion of some inspecting officers, a partial discharge of the required battery capacity would make it illegal to occupy a building. For example, if the emergency lighting in some business premises was inadvertently switched on - say, early in the morning - then the proper course would be for the occupier not to admit the staff or public to the premises until the correct minimum battery duration had been restored - an operation which might take 6, 8 or 12 hours according to the specification of the batteries (see Section 6.2).

One way out of this difficulty would appear to be to provide a larger battery capacity than is needed for compliance with the Fire Certificate. Then, it is claimed, a partial discharge for test purposes (or inadvertently) would still leave at least the mandatory minimum duration which must always be available from the batteries when the premises are occupied. The logic of this is flawed, for if the battery is not tested for its full capacity, how can one be certain that the required 1-, 2- or 3-hour duration will still be available if a power failure occurred after the deliberate or inadvertent partial discharge?

A practical method would be to arrange for a contractor to bring a mobile power supply to the building, and to connect it into the circuits to take over the emergency supply duty while the batteries in the installation are being test-discharged and then recharged (see Section 9.3). The mobile power unit could consist of a bank of batteries, or could embody an engine and generator. Such equipment, mounted on a vehicle or trailer, may be hired from specialist suppliers.

In the case of very large continuously-occupied establishments with hundreds of emergency lighting luminaires, it could be economic to


economic to invest in a mobile power unit which could be brought to each building in the complex in turn when it is time to carry out the testing of emergency lighting luminaires.

11.4 Maintenance and repair

11.4.1 Neglect easily occurs

At a number of industrial and commercial premises visited by the author it was noted that the general standard of cleanliness of emergency lighting and exit signing was often very poor, and on several occasions obviously defective equipment was seen (see Section 9.2). This could only mean that the routine inspections and tests recommended in BS 52664 were not being carried out, and that the standards of reliability and safety called for in the standard were not being achieved in those installations.

11.4.2 Carrying out maintenance work on time

Luminaires and signs etc should be cleaned at regular intervals for reasons of hygiene and to maintain the optical, electrical and thermal performance of the equipment. When the time scale is extended, important measures of maintenance or replacement of equipment may be overlooked by those responsible for the care and maintenance of emergency lighting systems (see Section 5.3). The life of emergency lighting equipment may be longer than the period of employment of those responsible for its care, so the keeping of proper records is vital to enable the work to be done by successive persons who become responsible. Better performance of these duties may ensue if a detailed log of maintenance and repair actions is kept, and if a schedule with a 5-year or 10-year span is maintained to ensure that replacements of items having finite lives such as lamps, batteries, titrium-activated self-luminous signs (see Section 5.3), etc, are signalled to ensure that the work is carried out on time. For the care of emergency lighting installations in both large and small premises, there is much to be said for the occupier entering into a long term


contract for regular inspection and maintenance to be carried out by a competent outside specialist contractor.

11.4.3 Some cautions

Persons carrying out maintenance on emergency lighting systems should observe the following:

• Only suitably qualified persons should carry out repairs to emergency lighting systems (see Section 9.1).

• Only replacement parts which have been approved by the supplier of the luminaires should be used.

• Before cleaning any equipment or carrying out any repair or adjustment, isolate the luminaire from the mains.

• Replace failed lamps promptly, as neglect to do this may damage the control unit.

• Avoid contact with hot lamps. • Do not touch the envelope of tungsten-halogen lamps with the

bare hand - this can cause early failure of the lamp. See the lamp maker's instructions.

• When replacing a fluorescent lamp, do not touch the pins or connections as the inverter may still be live even though it has been isolated from the mains.

• Use only lamps of the types and wattages marked on the luminaire or specified in the manufacturer's instructions.

• When carrying out maintenance or repair of emergency lighting in a hazardous zone, observe the safety requirements for that zone. Do not open any electrical enclosure nor make or break any live electrical connection in a flame hazardous zone without attention to the requirements of that zone (see Section 7.4).

• Do not carry out any modification or adaptation of an emergency lighting unit without the manufacturer's agreement, for this could invalidate the manufacturer's guarantee.

• Dispose of batteries, replaced components and failed lamps in accordance with the manufacturer's instructions. Do not open any battery nor burn it.

• Failure to carry out discharge/recharge cycle tests of batteries at the specified intervals will result in their giving lower duration when required to perform, and will shorten the life of the batteries (see Section 6.2).


11.4.4 Spares

Care of emergency lighting installations will be made easier by maintaining a stock of replacement items, e.g. lamps, starter canisters, control gear units etc, and spare luminaires. Note that some types of batteries have a limited shelf life.

11.5 Certification

11.5.1 Completion Certificates

BS 5266:Part I4 requires the completion of a Completion Certificate for a new or altered emergency lighting installation, and such a certificate shall be available for inspection by the enforcing authority which issues a Fire Certificate for the premises. The person signing the certification may be:

• a suitably qualified electrical engineer or a member of the Electrical Contractors' Association or the Electrical Contractors' Association of Scotland;

• a certificate holder of the National Inspection Council for Electrical Installation Contracting;

• a qualified person acting on behalf of one of the above (who must state on the certificate on whose behalf he is acting).

Additionally, where acceptable to the enforcing authority, the authorized representative of a manufacturer of emergency lighting equipment may be deemed to be a suitably qualified person.

11.5.2 Periodic Inspection and Test Certificates

The qualifications for the person signing Periodic Inspection and Test Certificates are generally similar to those required for signing a Completion Certificate (see Section 11.5.1).

11.5.3 Production of certificates

The premiums for insurance for premises are often quoted from a standard scale, and do not necessarily take into account details of


safety and protection measures that may be installed. Experience indicates that lower premiums may be quoted by insurers if they are shown that, in addition to all legally required safety and protection measures being in place, there are additional measures designed to reduce the incidence of loss or injury (e.g. way-guidance systems, or enhanced methods or levels of emergency illuminance). It is recommended that a copy of the Completion Certificate (and details of the emergency lighting and other fire protection systems) shall be made available to the insurers of the premises, and that the insurers should receive copies of subsequent Periodic Inspection Certificates for the emergency lighting system.

Appendix A Buyers' guide to UK emergency lighting equipment suppliers

The letter codes indicate the products and services supplied, thus: A = Integral-battery emergency lighting luminaires. B = Slave emergency lighting luminaires. C = Integral battery emergency signs. D = Slave emergency signs. E = Emergency lighting luminaires for rugged conditions. F = Emergency lighting luminaires for wet and steamy conditions. G = Hoseproof emergency lighting luminaires. H = Emergency lighting luminaires for outdoor use. I = Vandal-resistant emergency lighting luminaires. J = Emergency lighting luminaires for hazardous zones. K = Central battery systems for emergency lighting. L = Fibre-optic emergency lighting systems. M = Non-electric emergency/exit signs. N = Combined 'normal lighting + emergency lighting' luminaires. O = Floor/skirting-board escape guidance lights/signs. P = Handrail lighting to aid escape in smoke. Q = Infra-red switching for test. R = Other emergency lighting products. S = Will sell emergency lighting equipment directly to users. T = A free emergency lighting design service is offered. U = Will undertake installation of emergency lighting. V = Will undertake maintenance of emergency lighting. W = Can provide temporary stand-by supply during testing of

emergency lighting in continuously-occupied areas. X = The supplier is certified as quality assured to BS 5750.

ABB Control Ltd, Grovelands House, Longford Road, Exhall, Coventry CV7 9ND. Tel: 0203 368500. Fax: 0203 364499. ( A B C D H I J K N S T X ; Automatic monitoring and testing).


Absolute Action Ltd, Mantle House, Broomhill Road, Wandsworth, London, SW18 4JQ. Tel: 081 871 5005. Fax: 081 877 9498. (Fibre optic emergency lighting systems). Andrew Chalmers and Mitchell Ltd, 388 Hillington Road, Glasgow G52 4BL. Tel: 041 882 5555. Fax: 041 883 3704. ( A B E F G H I J S T X ) .

Anglepoise Lighting Ltd, 51 Enfield Industrial Area, Redditch, Worcestershire B97 6DR. Tel: 0527 63771. Fax: 0527 61232. (AD NX). H & L Appleby Ltd, Coltham Road, Short Heath, Willenhall, West Midlands WV12 5QE. Tel: 0922 710600. Fax: 0922 405624. ( A C E F G H I N ) . Armada Lighting and Fire Ltd, Unit 1, Huxley Close, Newnham Industrial Estate, Plympton, Plymouth PL7 4JN. Tel: 0752 342942. Fax: 0752 342864. ( A B C D E F G H I K N T ) . Arrow Plastics Ltd, Arrow Works, Hampden Road, Kingston-upon-Thames, Surrey KT1 3HQ. Tel: 081 546 62258. Fax: 081 541 4654. (X; Diffusers and controllers in polycarbonate and acrylic).

Beta Lighting Ltd, 383/387 Leeds Road, Bradford BD3 9LD. Tel: 0274 721129. Fax: 0274 305007. ( A B C D E F H I N S T ) .

Chloride Bardic, Southgate Way, Orton Southgate, Peterborough, PE2 6YG. Tel: 0733 371714. Fax: 0733 371940. (A B C D E F G H I J K N P T U V W X; Monitored emergency lighting). Concord Lighting, 174 High Holborn, London WCIV 7AA. Tel: 071 497 1400. Fax: 071 497 1404. ( A B E G H N S T X ) . Crompton Parkinson (Lighting) Ltd, Wheatley Hall Road, Doncaster, South Yorkshire DN2 4NB. Tel: 0302 321541. Fax: 0302 323934. ( A B C D F G H I S T X ) . Cryselco Ltd, 274 Ampthill Road, Bedford MK42 9QJ. Tel: 0234 273355. Fax: 0234210867. (AFGX).

Appendix A 159

Defence Components Ltd, 7 Salisbury Road, Hungerford, Berkshire, RG17 OLG. Tel: 0488 684625. Fax: 0488 683184. ( A B C D E F G H I J K O P Q T ; LED and EL sources for inclusion in other systems). Emergi-Lite Safety Systems Ltd, Wesley Place, Wellington Road, Dewsbury, West Yorkshire, WF13 IHX. Tel: 0924 450880. Fax: 0924 450770. ( A B C D E F G H I J K N S T V W X ) .

Erskine Systems Ltd, Lee de Forest House, Eastfield, Scarborough, North Yorkshire YOU 3DU. Tel: 0723 583511. Fax: 0723 581231. (BKSVX).

Existalite Ltd, Project House, 18 Tallon Road, Hutton, Brentwood, Essex CM13 1TZ. Tel: 0277 263600. Fax: 0277 263592. ( A C E F H I L N O S T X ; Way-guidance systems).

Fluorel Ltd, 312 Broadmead Road, Woodford Green, Essex IG8 8PG. Tel: 081 504 9691. Fax: 081 506 1792. (AFHNSX) .

Forest City, Park Road, Timperley Altrincham, Cheshire WA14 5QX. Tel: 061 969 0441. Fax: 061 905 1408. (Illuminated bollards with direction signs and ground-recessed direction signs for guidance of traffic and pedestrians).

Glamox Electric (UK) Ltd, 29 Coast Road, Wallsend, Tyne and Wear NE28 8DA. Tel: 091 262 7126. Fax: 091 262 4118. ( A B C D E F G H I J N O S T X ) .

GTE Lighting Ltd, Otley Road, Charlestown, Shipley, West Yorkshire BD17 7SN. Tel: 0274 595921. Fax: 0274 597683. (A E F H I N X; Conversion of tubular lighting systems to maintained mode). Harvey Hubbell Ltd, Ronald Close, Woburn Road Industrial Estate, Kempston, Bedfordshire, MK42 7JJ. Tel: 0234 855444. Fax: 0234 854008. (BDNX).

Holophane Europe Ltd, Bond Avenue, Bletchley, Milton Keynes, MK11JG. Tel: 0908 649292. Fax: 0908 270006. ( A E F G H I J K N S T X ) .


HT Systems Ltd, Ridgeway Industrial Estate, Iver, Buckinghamshire 5LO 9HU. Tel: 0753 654411. Fax: 0753 630002. (AKNSTUX).

Industrolite Ltd, Unit 3, Brazil Close, Beddington Farm Road, Croydon, Surrey CR0 4XQ. Tel: 081665 7070. Fax: 0816841407. ( A B C D E F G H I K N O P Q S T ) .

JSB Electrical pic, Manor Lane, Holmes Chapel, Cheshire CW4 8AB. Tel: 0477 37773. Fax: 0477 35722. ( A B C D E F H I J K N T V X ) .

Lab-craft Ltd, Bilton Road, Waterhouse Lane, Chelmsford, Essex CM12UP. Tel: 0245 359888. Fax: 0245 490724. ( A B C D F H I K M N S T X ; Offer free MSDOS design software).

Lumitron Ltd, Chandos Road, London, NW10 6PA. Tel: 081965 0211. Fax: 081965 8629. (ANSX).

Mackwell Electronics Ltd, Leighswood Grove, Aldridge, Walsall, West Midlands WS9 8SY. Tel: 0922 582255. Fax: 0922 51263. (X - Self-contained battery modules, batteries and inverters).

Maylectro, Lower Moor Way, Tiverton, Devonshire, EX16 6SS. Tel: 0884 242848. Fax: 0884 242292. ( A B C D E F G H I K N T U V X ; Monitored emergency lighting).

Menvier (Electronic Engineers) Ltd, Southam Road, Banbury, Oxon, OX16 7RX. Tel: 0295 256363. Fax: 0925 270102. ( A B C D E F G H I K L N T V ) .

Moorlite Electrical Ltd, Burlington Street, Ashton-under-Lyme, Lancashire OL7 0ΑΧ. Tel: 061 330 6811. Fax: 061 330 2815. (ABFGHISTX) .

Orbik Electronics Ltd, Orbik House, Northgate, Aldridge, Walsall, West Midlands W59 8TH. Tel: 0922 743515. Fax: 0922 743173. (X; Emergency lighting control gear).

P4 Ltd, 7 High Street, Clophill, Bedford, MK45 4AB. Tel: 0484 854330. Fax: 0484 854330. ( A C E G H I N S T U V ; Self-testing integral battery emergency lighting conversion kits).

Appendix A 161

Petrel Ltd, Thimblemill Lane, Birmingham B7 5HT. Tel: 021328 5055. Fax: 021 326 6290. (JSTX).

Philips Lighting, City House, 420-430 London Road, Croydon CR9 3QR. Tel: 081665 6655. Fax: 081 689 2752. ( A B E F G H I K N S T X ) .

Poselco Ltd, Walmsgate Road, Perivale, Middlesex UB6 7LX. Tel: 081 998 1431. Fax: 081 997 3350. ( A B C D E F G H I M N O S T X ) .

Protec Fire Detection pic, Protec House, Churchill Way, Nelson, Lancashire BB9 6RT. Tel: 0282 692621. Fax: 0282 602570. (AB C D E F G H I J K L M N O P Q S T U V W X ; Self-testing emergency lighting control systems).

Rada Lighting Ltd, Hollies Way, High Street, Potters Bar, Herts EN6 5BH. Tel: 0707 43401. Fax: 0707 45548. ( A B C D E H I N S T V X ) .

Ring Electronics, Gelderd Road, Leeds, LS12 6NB. Tel: 0532 798887. Fax: 0532792591. ( A B C D E F G H I K N O Q T V X ) .

Saunders-Roe Developments Ltd, Millington Road, Hayes, Middlesex, UB3 4NB. Tel: 081573 3800. Fax: 0815613436. (CD ST).

Security Lighting, PO Box 12, Peterborough, PE2 6UY. Tel: 0733 371500. Fax: 0733 371560. ( A B C D E F H I J K N T V W X ) .

Selite Group Ltd, Stafford House, 19 Stafford Road, Croydon, Surrey CR0 4NG. Tel: 081686 9919. Fax: 081680 9288. (ABCDEFGHIJKLMNQSTV;Conversionkitsforl2V dichroic lamps etc).

Silvertown Lighting, Springwood Industrial Estate, Braintree, Essex CM7 7QX. Tel: 0376 43434. Fax: 0376 21873. (ABNSTX).


Taison Lighting, Taison Industrial Park, Great Horton Rd, Bradford,West Yorkshire, BD7 4EN. Tel: 0274 521550. Fax: 0274 521481. ( A B C D E F G H I N T ; Maintained emergency lighting conversion kits). Thorn Lighting, Elstree Way, Borehamwood, Hertfordshire, WD6 1HZ. Tel: 081 905 1313. Fax: 081905 1278. ( A B C D E F G H I N T X ) .

Thorlux Lighting, F. W. Thorpe pic, Merse Road, North Moons Moat, Redditch,Worcestershire B98 9HH. Tel: 0527 584058. Fax: 0527 584177. ( A B E F G H I N S T X ) .

Tungstone Batteries Ltd, Market Harborough, Leicestershire LE16 9EZ. Tel: 0858 410900. Fax: 0858 463396. (KVWX).

Appendix B Useful names and addresses

British Electrotechnical & Allied Manufacturers' Association (BE AM A), Leicester House, 8 Leicester Street, London EC2H 7BN. Tel: 071 437 0678. Fax: 071 734 2406. (Trade association of electrical manufacturers) British Standards Institution (BSI), Enquiry Department, Linford Wood, Milton Keynes, MK14 6LE. Tel: 0908 221166. Fax: 0908 320856. Building Research Establishment (BRE), Garston, Watford WD2 7JR. Tel: 0923 894040. Fax: 0923 664010. (Publications relating to wise use of energy and the greenhouse effect) Chartered Institution of Building Services Engineers (CIBSE), Delta House, 222 Balham High Road, London SW12 9BS. Tel: 081 675 5211. Fax: 081 675 5449. (Publications giving recommendations on practice relating to many aspects of lighting - list on application. May advise on selection of consultants.) Commission Internationale de l'Eclairage (CIE), (The UK represen-tative may be contacted through CIBSE) Cyanamid of Great Britain (CLD), 3 The Potteries, Wickham Road, Fareham, Hampshire, P016 7HZ. Tel: 0329 221664:. Fax: 0329 825834. (Chemiluminescent lightsticks) Department of Trade and Industry (DTI), Radiocommunications Agency, Waterloo Bridge House,Waterloo Road, London SEI 8UA. Tel: 071 215 5000. (Information on radiofrequency interference; agency to which complaints should be directed)


Electrical Contractors' Association (ECA), 32/34 Palace Court, London W2 4HY. Tel: 071 229 1266. Fax: 071 221 7344. Electricity Association, 30 Millbank, London SW1P 4RD. Tel: 071 834 2333. Fax: 071 931 0356.

ERA Technology Ltd, Cleeve Road, Leatherhead, Surrey, KT22 7SA. Tel: 0372 374151. Fax: 0372 374496.

Fire Protection Association, 140 Aldersgate Street, London EC1A 4HX. Tel: 071 606 3757. Fax: 071 600 1487. (Provide advice, training, and publications on fire safety.) Health and Safety Executive (HSE), Baynards House, 1 Chepstow Place, London W2 4TF. Tel: 071 243 6000 and 071 221 0870. Fax: 071 727 2254. (Information & Publications Dept open 10am-3pm).

Other HSE offices:

Sheffield: Tel: 0742 768141/0742 752539; Bootle: Tel: 051 951 4381; Re EEC Health and Safety Directives: a free short guide is available: call 071 221 0870 or 0742 752539 between 10am & 3pm.

Institute of Environmental Engineering, The South Bank Polytech-nic, 103 Borough Road, London, SEI 0AA. Tel: 071 928 8989. Fax: 071 261 9115. (Continuing professional education)

Institution of Lighting Engineers, Lennox House, 9 Lombard Road, Rugby CV21 20Z. Tel: 0788 76492. (May advise on selection of consultants) Lighting Industry Federation Ltd (LIF), Swan House, 207 Balham High Road, London, SW17 7BQ. Tel: 081 675 5432. Fax: 081 673 5880. (Trade association of lighting manufacturers. Publications available, list on application) The Loss Prevention Council, 140 Aldersgate Street, London EC1A 4HY. Tel: 071 606 3757. Fax: 071 600 1487. (List of publications available, covering a comprehensive range of publications and visual aids containing technical information and guidance on the elements of loss prevention and control. Publications

Appendix B 165

give specific advice on fire prevention in offices, industry, shops, hotels, etc.) National Inspection Council for Electrical Installation Contracting (NICEIC), Vintage House, 37 Albert Embankment, London, SEI 7UJ. Tel: 071 582 7746. Fax: 071 820 0831. (Quality assurance for electrical contracting)

RFI Shielding Ltd, Warner Drive, Springwood Industrial Estate, Rayne Road,Braintree, Essex CM7 7YQW. Tel: 0376 42626. Fax: 0376 46442. (Specialist providers of electromagnetic interference shielding)

Appendix C Fires in dwellings

Every year fire brigades in the UK are called to some 60,000 fires in homes, and every year more than 900 people die in these fires and over 10,000 are injured.

C.1 Precautions

Guidance on reducing fire risk in residential buildings is given in the Code of Practice for Residential Buildings given in Part 1 of BS 558831. It is clear that many deaths and injuries could be prevented if the occupiers would take some simple steps to improve fire safety. Important among these are:

• Fit a smoke alarm.

The Home Office leaflet Wake up! Get a smoke alarm37 recommends the fitting of one or more smoke alarms conforming to BS 5446 Part

• Ensure that every room has at least one openable window through which escape would be possible in a fire.

Many homes which have double glazing are potential deathtraps, for the windows do not open. It is almost impossible to break the glass of a double-glazed window, even by hitting it with a chair.

• Fit internal doors having improved fire-resistance.

Many modern homes have internal doors that are hollow and are constructed of thin plywood, hardboard or other flammable materials which can burn through in a matter of moments. It could be beneficial to replace these with solid timber internal doors which have greater fire resistance and will slow down the spread of flame.

AppendixC 167

C.2 What to do if fire breaks out in your home

The Home Office leaflet A fire survival guide39 advises:

• Plan your escape route now. Don't wait until a fire starts. • Try to prevent fire starting in the first place - it takes only an

unguarded or careless moment for fire to start. • Smoke and fumes can kill - particularly the highly poisonous

smoke from some furniture; a couple of minutes later your home could be filled with smoke. You will have only a short time to get out; use it wisely and try not to panic.

The leaflet gives following guidelines on how to behave in a domestic fire: 1. To help delay the spread of flames and smoke, if you can safely do

so, close the door of the room where fire has started, and close all other doors behind you.

2. Before opening a closed door, touch it with the back of your hand. Don't open it if it feels warm - the fire will be on the other side.

3. Get everyone out as quickly as possible. Don't try to pick up valuables or possessions. Try not to panic.

4. Telephone the fire brigade on 999 from a neighbour's house or a phone box. State the address of the fire clearly.

5. Do not go back into your home until a fire officer has told you it is safe.

What to do if you are cut off by fire:

1. If you are prevented from getting out because of flames or smoke, close the door nearest the fire and use towels or sheets to block any gaps. This will help smoke from spreading into the room.

2. Go to the window. If the room becomes smoky, get down to the floor. It is easier to breath there because smoke will rise upward.

3. Open the window, try to attract the attention of others who can alert the fire brigade. Wait for the fire brigade, they should arrive in a matter of minutes.

4. If you are in immediate danger, drop cushions or bedding to the ground to break your fall from the window.

5. Get out feet first, and lower yourself to the full length of your arms before dropping.


C.3 Publications available

A number of posters, booklets, leaflets and stickers have been published by the Home Office and the Central Office of Information, giving information to the public on fire prevention and how to escape from fire. Current publications are listed in a Fire Safety Publicity Catalogue issued periodically by the Home Office. Fire Brigades and public organizations may obtain the catalogue and order these publications from: Fire Prevention Literature, PO Box 590, London SE99 7UT.

Private organizations may obtain the catalogue and order these publications from: Fire Prevention Literature, Room 133, Home Office, Queen Anne's Gate, London SW1H 9AT (Tel: 071 273 2756).

C.4 Emergency lighting in the home

As far as can be ascertained, there are no published guidelines dealing specifically with the subject of emergency lighting in private domestic dwellings, though it is clear that the provision of emergency lighting on stairs would be a valuable aid to safety, especially in households where there are children or elderly persons.

The recommendations for emergency lighting given in BS 52664 are applicable to domestic premises in multiple occupation (some of which are required to obtain Fire Certificates; see Sections 2.1 and 2.2).

C.5 New legislation on smoke detectors

According to a recent press report new UK legislation relating to smoke detection in dwellings is expected to come into force on 1 June 1992 (but may be delayed because of formalities of the European Commission). The Building Regulations 1991 will require that new dwellings shall be fitted with smoke detectors. For a two-storey house the requirements will be:

AppendixC 169

• at least one detector on each floor, and all smoke detectors in a building to be interconnected;

• detectors to be mains operated from a separate way on the distribution board, and wired in accordance with IEE Wiring Regulations.

It is commented that it would be prudent to install smoke-detector units having battery back-up.

References

1. Lyons, S., Lighting for Industry and Security, Butterworth Heinemann, Oxford (1992). ISBN 01463248. (A handbook for users and installers of lighting.)

2. Lyons, S., Security of Premises, Butterworths, London (1988). ISBN 0408013672. (A manual for managers of all kinds of premises.)

3. Fire Precautions Act 1971, HMSO, London: 4. BS 5266:Part 1:1988 Code of practice for the emergency lighting

of premises other than cinemas and certain other specified premises used for entertainment, British Standards Institution, London.

5. 'Europe moves on emergency lighting', report in Building Services, p. 5 (January 1991).

6. Factories Act 1961, HMSO, London. (Much of this act has now been replaced with new regulations under the Health and Safety at Work Act 1974. Many remaining provisions will be replaced by new EC-harmonized regulations in 1993, and in the next few years the act will disappear.)

7. Health and Safety at Work Act, 1974, HMSO, London. 8. CIBSE Code for Interior Lighting, Chartered Institution of

Building Services Engineers, London (1978). A new edition is in preparation; defines and explains standards for interior lighting and gives specific recommendations for various kinds of interiors.)

9. Guide to fire precautions in existing places of work, HMSO, London. ISBN 0113409060.

10. Technical Memorandum TM-12: Emergency Lighting, Chartered Institution of Building Services Engineers, London (1986).

11. Application Guide: Emergency Lighting (ICEL.1003), Lighting Industry Federation Ltd, London.

12. BS 5499:1990 Fire safety signs, notices and graphic symbols, British Standards Institution, London.

References 171

13. EC Directive 8913921 EEC (14 June 1989) as amended by Directive 91I368IEEC (20 June 1991) relates to the approxima-tion of the laws of the Member States concerning machinery.

14. The Single Market - Machinery, Department of Trade and Industry, (October 1991). (A publication in the 'Europe Open for Business' series.)

15. Lyons, S., 'Confusion and ignorance in the field of emergency lighting', Electrical Times, (25 January 1980).

16. Emergency lighting, Item 83.9 of LIF Technical News Report, Iss.Tech.13, March 1991, Lighting Industry Federation, London.

17. BS 4533 - Luminaires, British Standards Institution, London. 18. 'OECD Report on Illiteracy', The European, P. 1 (27 February/4

March 1992). 19. Berman, S. M., Energy Efficiency Consequences of Scotopic

Sensitivity, paper at the annual conference of the Illuminating Engineering Society of North America, Montreal, (1991).

20. Dawson-Tarr, E., Fibre Optic Lighting, paper to ERA Conference on Lighting Developments and Applications (1991). ERA Conf.Proc.91-0001.

21. 'Laser fire escape system', article in Electrical Contractor (March 1992).

22. Perry, B., The Ariadne® Fire Escape System - A Brief Summary -The Market, press release issued by Perry Architects, London, (21 February 1992).

23. Lighting Guide LG06 - The Outdoor Environment, Chartered Institution of Building Services Engineers, London (1991).

24. IEE Wiring Regulations, Institution of Electrical Engineers, London. (Regulations for the Wiring of Buildings), 15th Edition and 16th Edition (both in force until 31 December 1992; 16th Edition alone in force from January 1993).

25. Dodillet, H-J., and Pears, I., 'Planning lighting for exterior car parks', in Lighting Equipment News, (February 1992).

26. BS 5489 - Road lighting; Part 9:1990 Code of practice for lighting for urban centres and public amenity areas, British Standards Institution, London.

27. BS 7499 - Manned security services: Part 1:1991 Code of practice for static guarding and mobile patrol services, British Standards Institution, London.

28. Electromagnetic Compatibility Directive 8913361 EEC. (Became law in UK 1 January 1992.


29. BS 5394, Part 1, 1988: Specification for limits and methods of measurement of radio interference characteristics of fluorescent lamps and luminaires. British Standards Institution, London.

30. CISPR-15: Limits and methods of measurement of radiointerfer-ence characteristics of fluorescent lamps and luminaires. Issued by the International Special Committee on Radio Interference (CISPR) and available from Lighting Industry Federation and British Standards Institution.

31. BS 5588 - Fire precautions in the design, construction and use of buildings, British Standards Institution, London.

32. BS 5490:1977 Specification for classification of degrees of protection provided by enclosures, British Standards Institution, London.

33. Hospital Technical Memorandum No. 11 'Emergency electrical services*, HMSO, London.

34. Technical Memorandum TM16 Fire Precautions, Chartered Institution of Building Services Engineers, London. (1990). Source of information on legal and other requirements.

35 BS 5225 :Part 3 1982 (1988) Method of photometric measurement of battery-operated emergency lighting luminaires, British Stan-dards Institution, London.

36. BS 667:1968 (1985) Specification for portable photoelectric photometers, British Standards Institution, London.

37. Wake up! Get a smoke alarm, the Home Office and Central Office of Information, London. Pubn FB2 in series Tire Safety in the Home'.

38. BS 5446 Part 1:1990 Specification for self-contained smoke alarm and point type smoke detectors, British Standards Institution, London.

39. A fire survival guide the Home Office and Central Office of Information, London. Pubn FL03M in series Tire Safety in the Home'.

40. Fry, G., 'Clean power' (article on nickel hydride batteries), Electrical Design, p. 27 (February 1992).

41. Aizlewood C. E. and Webber, G. M. B., Emergency escape route lighting; a comparison of human performance with traditional lighting and wayfinding systems, paper presented at CIBSE National Lighting Conference, (April 1992) and to be published in the Conference Proceedings. (Reviews performance of test subjects traversing a route equipped with emergency lighting and

References 173

subjects traversing a route equipped with emergency lighting and with various systems of luminous way-guidance.)

42. 'New law on smoke alarms', editorial feature in Electrical Contractor, p. 5. (April 1992).

Further Reading

In addition to the foregoing references which are cited in the text, the following documents may also be useful sources in connection with the provision of emergency lighting:

• Regulations and explanatory documents

Electricity at Work Regulations 1989, HMSO, London. Offices, Shops and Railway Premises Act 1963, HMSO, London. Memorandum of Guidance on the Electricity At Work Regulations,

Health and Safety Executive. Bertonshaw, D. R., Recent Developments in Luminaire Safety, paper

to ERA Conference on Lighting Developments and Applications, (1991). (ERA Conf. Proc. 91-0001).

Baker, J. E., Overview of Regulations and Standards - Lighting, paper to ERA Conference on Lighting Developments and Applications, (1991). (ERA Conf. Proc. 91-0001).

• Lamps and luminaires

Lamp Guide, Lighting Industry Federation Ltd, London, (1990). Describes lamp types and gives their designations, powers etc.

Factfinder: Benefits of Certification, Lighting Industry Federation Ltd, London. Explains the BSI safety mark certification for luminaires.

• Hazardous areas

Factfinder: Hazardous Area Lighting, Lighting Industry Federation Ltd, London. Gives guidance on selection of lighting equipment.


List of Approved Equipment, published by British Approvals Services for Electrical Equipment in Fiery Atmospheres (BASEEFA); available from Health and Safety Executive.

BS 5345 - Code of practice for selection, installation and maintenance of electrical apparatus for use in potentially explosive atmospheres (other than mining applications or explosive processing and manufacture), British Standards Institute, London.

BS 5490 - Specification for classification of degrees of protection provided by enclosures, British Standards Institute, London.

BS 6467 - Electrical apparatus with protection by enclosure for use in the presence of combustible dusts, British Standards Institute, London.

Index

References are to sections and paragraph

Access to luminaires, 8.5 Adaptation, 3.1 Automatic self-testing, 11.2.2

Batteries, characteristics, 6.2 Batteries, disposition of, 6.1 Batteries, duration, 6.2 Beacon lighting, 3.5.5 Behaviour of public in fires, 3.2.1 Bland field effect, 3.1.4 Bollards, illuminated, 7.2.4 Broad arrow sign, 5.2.5 Broad arrow sign in reversed format,

5.2.6

Central batteries, 6.1.1 Certification, 11.5 Chevron arrow, 5.2.8 Colour in emergency lighting

(illuminant), 3.1.5 Colour of signs, 3.1.5, 5.2.9 Combined luminaires, 4.1.2,4.2.3 Common law duties of occupier, 2.1 Comparison of emergency lighting

systems, 3.4.1 Consultation, 8.1 Continuously-occupied areas, testing in,

11.3 Contractual responsibilities, 2.3 Conversion kits, 4.1.5, 4.4.5 Crime-prevention aspects of emergency

lighting, 1.3 Curved passages, lighting for, 3.6.11 Cut-off angle, 3.1.3

Daily inspection ,11.1.1 Defective installations, 9.2 Densely-occupied areas, 3.4

lumbers)

Directional signalling by linear lamp arrays, 5.4.5

Dirty areas, 8.5 Disability glare, 3.1.3 Discomfort glare ,3.1.3 DIY emergency lighting, 4.4.6 Doors, self-closing, 1.2.1 Duration of battery output, 6.3.1 Dwellings, fires in, Appendix C

Educating the public, 5.2.10 Electroluminescent way-guidance strips,

5.4.5 Emergency management, 8.4 Emergency systems, 8.4 Enclosures of luminaires and signs, 4.1.2 Escalators, 3.6.1 Escape routes, 1.2, 3.2 Escape route guidance, 2.2.6 Exit doors, final, 8.4.8 Exit pictogram, 2.2.5 Exterior locations, 7.2 Externally-illuminated signs, 4.1.4

Factories Act, 2.2.1 Fear - effect on vision, 3.1.4 Floor-floods, low-mounted, 4.3 Filament-lamp linear arrays, 5.4.5 Fire alarms, 1.2.1,8.4 Fire Certificate, 2.2.1 Fire, deliberately caused, 1.3 Fire detection, 1.2.1, 8.4.4 Fire precautions, 1.2, 8.4.1 Fire Precautions Act, 1.2 Fire statistics, 1.1 Floor-recessed way-guidance systems,

5.4.3

Glare, 3.1.3 Glass bowl luminaires, 4.4.3

176 Index

Handicapped persons, 3.6.2 Handlamps, 7.5.3 Handrail system, illuminated, 5.4.5 Hazardous zones, 7.4 Hazard warnings, 5.2.7 Health & Safety at Work Act, 2.2.1 High-bay installations, 7.1.2 Hospitals, 3.6.1 Hotels, 3.6.7

Laser systems, 5.4.5 LEDs, 5.4.5 Legibility of exit signs, 5.2.2 Legislation relating to emergency

lighting, 2.2 Lifts (elevators), 3.6.9 Light-emitting diodes, 5.4.5 Lightmeters, 10.2.2 Locations of exit signs, 5.1.2 Low-mounted floor-flood luminaires, 4.3 Luminance, 3.1.3 Luminance of way-guidance systems,

3.4.2 Luminosity, 3.1.3

Machine lighting, 2.6 Maintained mode, 4.2.1 Maintenance, 11.4 Mobile lighting, 7.5 Modes of operation, 4.2 Modification kits, 4.1.5

Nickel hydride (NiH) batteries, 6.2.3 Night myopia, 3.1.4 No-break power supplies, 6.3.4 Non-cut-off luminaires, 4.4.4

Non-electrical escape route signs, 5.3 Non-escape-route signs, 5.2.8 Non-maintained mode, 4.2.2 Non-preferred equipment. 4.4 Nuisance, 2.5

Objectives of emergency lighting systems, 1.1

Outages, long, effect of, 1.4.2 Outdoor areas, 3.5 Outdoor exit routes, 7.2.4 Outdoor industrial areas, 7.2.2 Outdoor parking areas, 7.2.7 Overheating of luminaires, 4.4.6

Panic, 3.4.2 Parking areas, 7.2.7 Periodic inspection, 11.1.2 Personal lights, 3.5.7 Photoluminescent materials, 4.4.1 Pictogram, 2.2.5,5.2.3 Pilot lighting, 3.5.5, 8.3.2 Pilot lighting, outdoors, 7.2.4 Place of safety, 3.7 Portable lighting, 7.5,4.4.3 Power supplies, security of, 1.4.1 Public transport, 3.6.5

Quality of equipment, 8.2.3

Reliability of installations, 9.1 Repair of installations, 11.4 Residential premises, 3.6.7, Appendix C Response time to mains failure, 10.1.1 Retail stores, 3.6.6 Retrofit conversions, 4.4.5 Risk, reduction of, 1.2.1 'Running man' pictogram, 5.2.3

Safe movement at low lighting levels, Chapter 3

Safety of installations, 9.1 Safety ratings, arbitrary, 3.4.2 Schools, 3.6.4 Security of power supplies, 6.3.1 Self-testing of emergency lighting, 11.2.2 Shared premises, 2.4 Shock - effect on vision, 3.1.4

Illiteracy affecting reading of signs, 5.2.2 Illuminance measurements, 10.2 Illuminance on the floor, 3.4.2 Illuminance recommendations, 10.1 Infra-red testing, 11.2.1 Inspection, daily, 11.1.1 Inspection, periodic ,11.1.2 Installations, 7.1 Integral batteries, 6.1.1 Integral machine lighting, 2.6 Integrating emergency lighting with other

lighting, 8.3

Index 177

Shopping malls, 7.2.6 Signs, 2.2.5,5.1 Single-point emergency luminaires, 4.1.2 Slave emergency luminaires, 4.1.2 Sloping floors, ramps, 3.6.12 Smoke control, 1.2.1,8.4.7 Smokefilled areas, 3.3 Smoke hindering escape, 3.2.2 Solar-powered emergency lighting, 4.4.7 Specifications, 8.2 Sports premises, 7.2.5 Spotlight units, 4.4.2 Stadia, 7.2.5 Stairs, 3.6.10 Stand-by lighting, 1.4 Stand-by power supplies, 6.3 Sub-miniature filament lamps, 5.4.5 Symbols, 2.2.5

Temporary lighting, 7.5 Tenancies, 2.4 Testing, infra-red ,11.2.1 Testing of installations ,11.1 Tests of battery capacity, 11.2 Tests of new concepts in emergency

lighting, 3.3.2

Titrium-activated systems, 5.4.3 Torches, 7.5.3

Uniformity of illuminance, 3.1.2 Unseeing sentry syndrome, 3.1.4

Visibility affected by smoke, 3.2.2 Visual defect affecting reading of signs,

5.2.2 Visual embarrassment, 3.1.4 Visual performance, 3.1

Wayfinding (way-guidance), 3.3 Way-guidance, outdoors, 7.2.4 Way-guidance systems, 5.4 White lining, 7.2.4 Windowless buildings, 3.6.13 Wording on exit signs, 5.1.3 Wall-mounted way-guidance systems,

5.4.4

Zonal batteries, 6.1.3

emergency lighting. for industrial, commercial and residential premises

Documents