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1: INTROUCTION The project involves the design of the complete electrical installation system for a Government Agency building. The scope of my project was to make the electrical design of the second, sixth and seventh floor of a building meant to be Government Agency building. The electrical installation design includes the in-coming power supply, low voltage switch board, electrical distribution, power and lighting, fire alarm and detection systems and earthing system. Lighting design is to be carried out to ensure a good lighting system, which provides the required levels of illumination as provided by the IES and the CIBSE codes for interior lighting. The important factor is to do the selection such that the effective light output is approximating the normal light in all aspects. The exterior lighting designs include flood lighting and security lighting and the lighting is done considering reasonable proximity. Calculations have to be carried out to determine the maximum load demand for the building, this also enables accurate sizing of the stand-by generators whose detailed specifications does not form part of this project. Since it is not easy to determine the power factor at which the building will be operating at until it is practically commissioned, an assumed power factor of 0.8 is considered as well as a diversity factor of 0.8 as these are acceptable industrial standards. Estimated costs for the project will be carried out in this report. This will be done using the current market rates. To estimate the cost involved: first quantities of material has to be calculated and scheduled in the bills of quantities in the specification section.

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1.1: OBJECTIVES: The main objective of this project would be to arm me with the necessary design skills, theoretical considerations and practical challenges associated with the design and analysis of Building Electrical and IT Services.The project is expected to meet the following objectives: d To use I.EE and CIBSE and all relevant British Standards Specification and

Codes of practice d To meet I.E.E. Regulations, Electric Power Act and By-Laws of KP & L

Co. Ltd., The I.E.E. Regulations for Electrical Installations, d To prepare a tender document and Bills of Quantities for the proposed

project thereby estimating the cost of the electrical works of the project.

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CHAPTER 2: LITERATURE REVIEW When it first came up, even experts in the building industry were not sure whether it could last. In fact some even predicted that it would soon wither away and succumb to stiff competition in the market place. But multi-functional building for higher education colleges came conquered and stayed. They are usually 4 to 5 floor buildings that house lecture halls, offices and other necessary rooms for the college within the same building. It is especially convenient because services such as security and parking are shared. Due to dynamic nature of the building, its design is quite involving due to the varying standards applicable in the provision of services based on the functionality of each unit. Normally, the lighting and low voltage power is carried out first or computation of the loading. Other things like the elevator loadings are considered. The total loading is then determined so as to enable one to determine the power distribution, sizes of generators and type of supply needed. In Kenya, electric power for buildings is usually purchased from KPLC. Before any electrical installations are carried out, KPLC is requested to provide information on the type of supply available: either single-phase or three-phase. Electric power is brought into a building through cables to an entrance control point and more often than not, to a meter in the building. It is then distributed throughout the accessories by means of additional conductors, which are often designed to carry a given current capacity. In later design stages, equipment requirements may be revealed gradually. As a result, equipment and its location may be changed and electrical loads have to be completely revised. As a result, the estimates of electrical loads have to be carefully made so that the electrical design can easily be modified to accommodate the load changes. Also, possible expansion of the building and its services has to be considered in order to ensure the effective design of the installation system.

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2.1: INCOMING ELECTRICITY SUPPLY The building electrical system is the final link in the power generation and delivery process. The 4 main sub-divisions in this process are: Generation, Transmission, Distribution and Utilization. This is illustrated below:

Fig.1: The Four Areas of Power System Activity 2.1.1 Generation: The method by which electricity is generated in a country reflects the resources available to that country. Dependence is placed on the most extensive natural resources in a country, e.g., coal, peat, water tidal basin, oil, natural gas, solar power, wind power and nuclear fuel. The extent to which any or all of these resources is available depends on the country and its ability to produce commercial quantities of electrical energy. Electricity is generated in power-generating stations which are often situated far away from the consumers of electric power and near the natural resources of energy. For example, large hydro-power generators are installed at places where a large quantity of water at a high head is available for driving turbines which in turn drive generators.

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In Kenya, we mainly use hydro-electric stations. Since most generating plants are located far away from consumers; there is need for transmission of power from the generating stations to the consumers. 2.1.2 Transmission Electricity is normally transmitted from the generating station to sub-stations through transmission lines. In Kenya, power generation is in three-phase at 11kV, 50Hz. The generated voltage is stepped up to 132kV-220kV by means of a step-up transformer for long distance transmission. This reduces the transmission losses since the power is transmitted at low current which also translates to reduction in cable sizes and switch gear capacities. Then by means of three wire transmission lines, electric power is carried to different places where it is received in sub-stations situated near the city or town. 2.1.3 Distribution At the sub – stations after transmission, the transmission voltages are stepped down to distribution voltages of 66kV or 33kV that are further carried through three-wire transmission lines to various sub-stations in the city and towns where the voltage is further stepped down to 11kV, 6.6kV or 3.3kV. These voltages are further stepped down to small consumers through 415/240V, 50Hz three-phase and four -wire distributors for domestic and non-domestic applications. 2.1.4 Utilization At this level, power is distributed to the various end users. These are mainly for lighting, electric heating, air conditioning, computer, security lighting and flood lighting. The building systems are the last step in the complex power generation and delivery process. Each type of building has a unique electrical installation requirement. My project has sought to specifically address the electrical requirements of a school of law and commerce building.

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2.1.5 Voltage Tolerance Current carried by the electrical power distribution network varies at different times of the day. This leads to varying voltage drops in the supply cables. It is thus impractical to give each consumer nominal supply voltages i.e. 415/240V at their terminals. Supply Authorities are therefore permitted certain tolerances. Under the Kenyan Electricity Rules, the voltage fluctuations may not vary by more than 5% above or below the declared nominal voltage and frequency must be within +/- I % of the declared frequency of 50Hz. In the industry set up, the applicable tolerance is 2.5%. 2.1.6 Termination Electricity will be supplied to the building by the Supply Authority. This supply will be provided by a cable brought from outside into a suitable point in the building which is referred to as the main in-take. From this the electrical sub-contractor will provide a space for housing the Authority's meters, current transformers and voltage transformers. It is from the above point that the sub-contractor will then provide a molded circuit breaker as specified and a by-pass switch for the stand-by generator before terminating the supply cable to a bus bar. From the bus bars, electricity is then distributed to the various electrical boards in the premises. 2.2 ELECTRICAL DISTRIBUTION SYSTEM 2.2.1 Low Voltage Switches and Switch Gear The switch gear is an assembly of the main and auxiliary switching apparatus for operation, regulation protection and other control of the electrical installations. Switch gear devices include circuit breakers, switches for protective equipment, meters, instrumentation and control equipment. Power from the secondary of the transformer is fed into the board low voltage switch for distribution into the building. Total incoming power is normally sub divided into several circuit

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breakers. A metal enclosed low voltage switch-gear will be used for this project and it includes the following equipment: d Low voltage power circuit breakers that are mounted stationary or removable

and contained in individual grounded metal compartment. d Bare bus and connections. d Instruments, meters and protective relays. d Instruments and control transformers. d Control wiring and accessory devices. d Circuits breakers controlled at the switch-gear with the circuit breakers being

removable, mechanical interlocks will be provided for proper operating sequence.

All main switches should be insulated in an enclosed pattern and be fixed at close proximity to the point of entry of the supply. The I.E.E. regulations clearly stipulate the following which should be taken into consideration when designing a switch board:

1. Open type switch shall be placed only in dry situations and in ventilated rooms and they shall not be placed in the vicinity of storage batteries or exposed to chemical fumes.

2. In a damp situation where inflammable or explosive dust, vapor or gas is likely to be present, the switchboard shall be totally enclosed or made flame-proof as may be necessitated by the particular circumstances

3. Switchboards shall not be effected above gas stoves or sinks, or within 2.5 meters of any washing unit in the washing room or laundries or in the bathrooms, lavatories or toilets or kitchens

4. Incase of switchboards unavoidably fixed in places with abnormal moist atmosphere, the outer casting shall be weather proof and shall be provided with glands and bushing or adopted to receive screwed conduit, according to the manner in which the cables are run

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The equipment in the LV switchboard should be mounted on the board such that there is no possibility of an inadvertent contact with live parts whenever a person is performing operations like changing circuit breakers or manipulating switches etc 2.2.2 Metering The supply authority normally meters the power afforded. For large buildings, current transformers are used for meter protection. The primary coil of the current transformer is connected to the line and the output from the secondary coil taken to the meter. 2.2.3 Distribution The size of the incoming cable is dependent on the expected maximum load demand. The current flowing along it must be divided among a number of smaller cables running to the various parts of the building. Since it is quite costly to run all sub-circuits from the main in-take point due to cost of cables and the excessive voltage drop, current is distributed to a number of distribution boards which split it further to a number of final sub circuits. This is mainly because it is economical and practical to divide the supply first over a few large cables and then into the final small cabled in the second step. 2.2.4 Cable Rating and Protection The sub main cable from the distribution must be rated to carry the maximum simultaneous current by all the final sub circuits on that board. Once the current is calculated by the designer, the size of the cable can be determined by the current carrying capacity and allowed voltage drop. For protection against short circuit and overload, a circuit breaker or other protective device at the main intake should be included. Distribution boards normally have circuit breakers thus the final sub circuits are protected. The electrical cable should be carefully installed and should not come into contact with other services such as water pipes, water tanks, etc. 2.2.5 Distribution Boards

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Position of the distribution board within a building is important and mainly depends on the plan of the building. Apart from architectural considerations, balancing of the sub mains and the length of the final sub circuits to find the most economical way of keeping the total voltage drop at a minimum is vital. It has been found wise to keep the number of distribution boards down by having a reasonable number of final sub-circuits on each board. To achieve this without excessive long final sub-circuits, it is normally necessary to have the board fairly central for all the circuits it is serving. The I.E.E Regulations stipulate that where fixed live parts between which (although more than 240V) are inside enclosures, although separate from each other but are within reach of each other, a notice must be displayed giving maximum voltage between the live parts. Within reach is usually taken to mean 2 meters. Since it is not pleasant to have many notices in a building saying 'Danger - 415V' it is prudent to plan the distribution inside the building so that circuits on different phases are kept more than 2 meters away from each other 2.2.6 Precautions Another factor to consider in design of electrical distribution is the position of the other services. If a fault develops on an electric cable, its protective casing i.e. sheath would become live. In selecting the cable routes, I have had to try and minimize the dangers arising from cable faults although protection is still afforded for such faults as discussed in other chapters of this project. For example if a live conductor breaks and touches the outer sheath or conduit the exposed parts become live. The protective device (say circuit breaker) will operate and trip but the small time lag before it trips although it may be milliseconds could prove fatal to someone touching the metal part to which the current leaks. For the above reason it is a good practice to have electrical wiring separated from other services by at least 1m. Where this is not possible the metal work of the earth continuity conductor of the electrical supply as stipulated by the I.E.E Regulations.

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2.3: LIGHTING DESIGN 2.3.1 General The main reasons for illumination are: d Functional

In building design, the roles of both daylight and electric light have to be considered. Daylight is usually supplemented by electric light in cases where daylight will not light a room to acceptable standards. Distinctive appearance of a room with daylight depends on: d Color of daylight d Its random changes of intensity and color d Good illumination of walls and other vertical surfaces in rooms with side

windows There should be enough light in the interior at all times to allow work or other activities to be carried on effectively and safely and to give its occupants the sense of a well lit building.

d Aesthetic The lighting system can also function as an architectural design tool in helping to determine both the appearance and the mood of various interior spaces, e.g. restaurants employ illumination systems to improve on the ambience.

d Security This is mainly for outdoor lighting. A carefully planned exterior lighting system can enhance the security of a premise. In some cases, they are integrated with the security systems.

2.3.2 Objectives The main design objectives are:

(a) Safety and health

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(b) Performance (c) Appearance and comfort.

Other design objectives take the form of physical constraints that include: (a) Energy consumption (b) Hazardous environmental considerations (c) Physical problems in installation of equipment (d) Access for maintenance

2.3.3 Design Consideration The level, quality and design of the lighting in an interior in which work of a visually exacting nature has to be carried out should be based on the requirements of d Size of the visual task and distance from the eye. d Visual Performance d Visual Comfort and pleasantness. d Energy and cost effectiveness (which as a long term effect on the

installation) The function of the room of occupancy and the visual tasks to be carried out determine the choice of the lighting system. The most common types are: (a) General lighting – that provide an approximately uniform luminance over

the whole working area.

Fig 2.1 (b) Localized lighting – This system employs an arrangement of luminaries related

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to the position of the tasks and workstations Fig 2.2 (c) Local lighting – This is mainly for workstations as they provide illumination

only over a small area occupied by the task.

Fig 2.3

Directional Effects in Lighting Flow of light can have either a direct component (coming from the light source) or indirect component (by reflection from room surfaces). The flow of light determines where the shadows will be cast and how dense they’ll be. A designer should consider these effects as some of the effects make it easier to see a task and others make it more difficult to see a task. The term modeling is used when considering these effects. This term describes the ability of light to reveal solid form. It is ‘harsh’ or ‘flat’ depending on relative strengths of the direct and diffuse components of the light reaching the object. Good modeling is essential for sculpture display and can also help to reveal the detail of many industrial tasks. 2.3.4 Lighting Level Three different levels of lighting can be established depending on the type of interior, and the activity carried out:

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1. The minimum for circulation areas 2. The minimum for working interiors 3. The optimum for working interiors.

2.3.4.1 The minimum for circulation areas: To be able to just barely discern the features on a human face a luminance of approximately 1cd/m square is necessary calling for a horizontally luminance of approximately 20lux. For this reason, 20lux is regarded as the minimum luminance value for all circulation (non-working) areas. 2.3.4.2 : The minimum for working interiors The perception of the features of the human face is judged as being just acceptable (meaning that these features can be satisfactorily recognize without any special effort) at a luminance of 10-20 cd/m square providing there is a controlled background luminance. This means that a vertical luminance of at least 100lux, and an even higher horizontal luminance, is required. A horizontal luminance of 200lux is regarded as the minimum that is acceptable for rooms where people stay for long periods, and for all working interiors especially lecture halls and offices 2.3.4.3 The Optimum for working interiors Investigations have been carried out in order to establish a preferred range of luminance levels for working interiors having average values of room surface reflectances. The maximum reflectance preferred is approximately 2000lux. The I.E.S. code of practice for interior design gives the recommended average luminance levels for different areas and purposes. 2.3.5 Glare It’s experienced if windows/luminaries, seen either directly or by reflection in shiny surfaces, are too bright compared with the general brightness within the interior. Excessive glare makes it difficult to recognize detail, or causes visual discomfort to people in the room or both. Direct glare can be caused by bright luminaries appearing in the field of view of an observer. Reflected glare will occur if the observer sees the reflection of a source in a glossy surface. Reflected glare from large surfaces and furnishings etc can be avoided by exercising care in the

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selection of materials reflection properties. Reflected glare from surfaces below eye-level tend more troublesome than that from above. Glare occurs in two forms which sometimes occur separately but are often experienced simultaneously. The first is known as disability glare and impairs vision objects. The second is known as discomfort glare and is generally experienced as a feeling of discomfort, which tends to increase with the passage of time thus causing fatigue. Glare is normally reduced in the following ways: d Calculating the glare index which should be lower than the limiting value of

the room d Opening luminaries fitted with louvers whose cut-off angles are sufficient to

prevent lamps being seen directly at normal angles of view. Values of limiting glare index for different installations are given in CIBSE Interior Lighting Code. An uncorrected Glare Index table is given which has glare indices for different installation layouts. These indices are used to calculate the discomfort glare index of an installation. Uncorrected glare indices must be corrected by adding (or subtracting) conversion terms for mounting height, total lamp flux per luminary and glare conversion term for the luminary version. Flicker: This is normally caused by the frequency variation in light output of the lamps. For incandescent lamps, the variation is small: for discharge lamps, including fluorescent lamps, the flicker is more pronounced. In order to avoid flicker, the following can be done: d Fluorescent lamps of high rated current when used for lighting an interior

should preferably be of the shielded electrode type to reduce flicker d The light over the task area can be supplemented with light from a local

incandescent lamp to reduce disturbing or confusing stroboscopic patterns. Also, stroboscopic effects and flicker can be lessened by:

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d Using 3-Ø electrical supplies and mixing the light from lamps on all phases as much as possible

d Using lead-lag circuits or d.c. circuits d Using high frequency supply or circuit where this is economically justified

2.3.6 Colour in Lighting The co lour of an object/surface as we see it depends principally on its: d Spectral reflectance d Spectral characteristics of light illuminating it d Way in which the eye responds to light of different wavelengths

The eye is generally more sensitive to light of certain colors than others. E.g. except in low brightness, the eye’s response is greatest to light in yellow-green region of the spectrum and least to light in the deep red and deep blue regions. The relative amounts of light radiated by sources in different parts of the spectrum are expressed conveniently by spectral power distribution curves. The recommendations include: d The lamps selected for lighting an interior or activity should have

appropriate colour appearance and co lour rendering properties d Lamps of cool co lour appearance shouldn’t b used in interiors with

relatively low luminance d Lamps having the correct colour rendering properties should be used d Unless for special reasons, lamps of the same colour appearance should be

used throughout an interior and not necessarily throughout a building

2.3.7 Lighting Control The need to conserve energy has produced many proposals to assist conservation. A frequently mentioned example of waste is the use of artificial lighting at times when day light would be capable of providing the required working luminance. The basic ways of controlling the level of the artificial lighting in an interior are:

• Manual ON/OFF control • Manual dimming

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• Automatic ON/OFF control • Automatic step-wise control • Automatic dimming

2.3.8 Lamp lumen depreciation The luminous output of all lamps decreases with use, but the rate of decrease varies widely between lamp types. Lighting calculations must, therefore, take into account the specific depreciation in luminous output of the particular lamps involved. For fluorescent lamps, which are used extensively in this project, the following factors are most likely to influence the rate of depreciation: d Lamp quality and type of phosphor (if used) d Quality of ballast (if used) and the type of associated circuit d Operating conditions e.g. switching cycle, tube wall temperature and

mounting position. Maintenance factor The factor is defined as the ratio of the average luminance on the working place after a certain period of use to the average luminance obtained under the same conditions for a new installation. It takes, therefore the overall depreciation caused by various factors. When determining the number of lamps necessary to provide the required luminance for a particular lighting installation, it is usual to apply a maintenance factor to the calculations. If no information on the depreciation of lamps luminaries and room surfaces, or the cleaning schedule is available, the values given below (general) can be used. The cleaning period is assumed to be 12 months.

-__

r_ ,.....

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Table

1: Propo

sed maintenanc

e factor

s for service value of luminance 2.3.9 Security & Outdoor Lighting Outdoor lighting is used for a variety of purposes in our modern society. For work or recreation, it enables people to see essential detail in order that they may undertake their activities at night. It can facilitate and enhance the safety and security of persons or property, for example through lighting pathways within the college environment. It may be used to emphasize features of architectural or historical significance, and to light parks and gardens. The different uses to which lighting is put, impose different requirements on the kinds and amounts of light needed, and give rise to differing potential adverse impacts. Because of this, lighting codes often distinguish the general types of lighting uses, and apply somewhat different standards for each. Most lighting is used for general illumination, to provide simple visibility in areas used by pedestrians (walkways), pedestrians and vehicles (parking lots) or vehicles alone (roadways) at night. The lighting is used to allow the relatively simple tasks of navigation, avoiding hazards such as people, curbs or other vehicles, and locating vehicles. Similar kinds of lighting and lighting code standards are applicable for security lighting. The relation of lighting to security is complex and uncertain, and one must be certain what is meant by "security." Various outdoor codes are adopted for these reasons.

Room Category Lamp lumen maintenance factor

Luminaries-and room surface dirty maintenance factor

Total maintenance factor.

Clean 0.9 0.9 0.8 Average 0.9 0.8 0.7 Dirty 0.9 0.7 0.6

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An outdoor lighting code is a legal document that establishes permitted and prohibited lighting practices, with an emphasis on limiting obtrusive aspects of lighting more than an emphasis on good lighting practices per se. Most lighting codes are concerned primarily with limiting the wide-reaching effects of stray light that causes glare, light trespass, sky glow, and limits the ability of persons to use property in ways that do not want or need lighting. 2.3.10 Emergency Lighting Emergency lighting is designed to come into operation when the normal lighting fails. Categories of emergency lighting are: 2.3.10.1 Escape Lighting This is defined as lighting sufficient to enable a building to be evacuated quickly and safely during an emergency. 2.3.10.2 Safety Lighting This is lighting that is sufficient to ensure the safety of persons engaged in work of a potentially hazardous nature and should not be less than 5% of that given by the normal lighting. 2.3.10.3 Standby-by Lighting This is lighting sufficient to allow activities of vital importance during an emergency. This is the type of lighting provided in this project. Each luminary has its own batteries, which normally "float" across the mains. In the event of a power failure, the batteries are automatically switched in. When power is restored the batteries go back on charge. This system is most reliable; individual lamps can go on functioning even during a fire or when the mains cable is destroyed. 2.3.10.4 Non-permanent lighting with automatic switching This type of lighting works from a central emergency generator or battery supply that automatically switches on during a mains failure. The disadvantage of this system is that it relies on the internal wiring on the building for distribution of the

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emergency power and can thus easily become disrupted in the event of fire, structural damage etc. 2.3.10.5 Maintained supply In this method the luminary is supplied from the normal supply, which may or may not include a generator back-up supply in case of failure. Further to this the luminary has a built-in battery and charger so that in case of failure on the normal supply it switches in. This is now being extensively used in most modern buildings. 2.4 POWER DISTRIBUTION IN A BUILDING 2.4.1 General The final outlets of an electrical system in a building are lighting points, socket outlets and fixed equipment. The wiring of each of these comes from a fuse or a circuit breaker in a distribution board or consumer unit. The circuit breaker must be large enough to carry the largest current ever taken in any one instant by the whole equipment on that sub circuit. The size of both the consumer board and the cable is governed by the type of outlets in the circuit. The size of the in-coming cables will be dependent on the expected maximum load demand and the current flowing along it must divided among a number of smaller cables to be taken to various destinations throughout the building. This division is a function of the distribution system. Most final sub-circuits are commonly wired in 1.5 mm2, 2.5 mm2 or 6 mm2 cables. The cable from the main in-take to a distribution board is known as a sub-main cable, and it is designed to carry the maximum simultaneous current taken by all the final sub-circuits on the distribution boards. Once the current is calculated, the size of the cable can be determined by the current carrying capacity and allowed voltage drop. The allowable maximum voltage drop in the industry is approximately 6% of the load at the final outlets.

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2.4.2 Ring Circuits Installation systems are normally designed in such a way that there are socket outlets for normal power supply and others specifically dedicated and designed for use by computers only. Computer power lines are known as clean lines and are served via a dedicated distribution board and consumer unit. The mode of ear thing for clean lines is different from the mode used for the normal power lines. This ensures that surges occurring in the system do not affect the operation of the computer systems. In some cases, a central Uninterruptible Power Supply (UPS) is usually connected to this line to ensure that computers in the entire building are not affected by the power failures and its instabilities.

2.4.3 Large Equipment Equipments larger than 3-4kw must have circuits for each of them. These include cooker control units for cookers. The appropriate circuit breakers have to be selected for them. These equipments are connected through a fused insulator or a switch fuse. 2.4.4 Isolation Since all equipment requires maintenance from time to time, they must therefore be installed in such a way as to enable maintenance to take place without interference to the rest of the circuitry since power has to cut off to the equipment in such a case. As a result, safety requirement regulations require that here should be an isolator within reach of the machines. Thus, isolators for different circuits and for the whole building should be provided during the design to enhance maintenance of the electrical system.

2.4.5 Protection Generally, protection is that of a faulty circuit. In the occurrence of this, the circuit should be isolated till the fault can be found and corrected. The angers involved in such a case are electric fires and electric shocks to people in the building. The main types of faults are: d A short circuit

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d An overload d A fault to earth

Various devices can be used to provide this protection. They include: re-wire able fuse, high breaking capacity fuses, Miniature Current Circuit Breakers (MCCBs), isolating transformer, etc. For this project, I will mainly use MCCBs. 2.5 EMERGENCY SUPPLIES 2.5.1 Standby Generators Power outages tend to be quite common thus we have to provide for standby power supply which in many cases has the components: d An alternator d Controls that transfer load from normal source to standby power source

Sources of standby power are: d Engine driven generators d Turbine driven generators d Store energy systems (accumulators)

The operation of the standby power system is illustrated below: The automatic changeover switch is initiated by a sensing unit that detects a drop in the mains voltage. One could also have a manual change over switch. The factors to consider in selection of a generator are: cost of fuel, purchase price, long-term maintenance costs, operation times, acoustic features, etc. Generators generally have to be housed in well aerated buildings and have an outlet vent for fumes if placed underground e.g. in basements.

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The generator rating is normally given by the formula:

Generator rating = Total load of the building X Diversity factor The applicable diversity factor in the industry is 0.7 – 0.8. 2.5.2 UPS (Uninterruptible Power Supply) Since computers are sensitive to voltage and frequency fluctuations, it is necessary to feed them through a network which smoothes out the fluctuations in the same power supply and suppresses the surges caused by switching of other equipment connected to the power supply. Clean lines in the system are normally connected via the UP

2.6 Lift Systems The installation of the lift systems is normally carried out by specialists who have to comply with the various recommendations given by the engineers and as stated in the tender documents dedicated to lift installation. The power supply to a lift or lift room may be fed by a separate sub-main cable from the main switch board. The maximum voltage drop when carrying the starting current as specified by lift manufacturers is 10V thus the cable should be of such a size to accommodate a 3-phase 415V supply. Since the local power supply can be erratic and prone to fluctuations and surges, the tenderer shall therefore allow for the necessary protection against power fluctuations and surges. The main switch gear should be labeled lifts and in the lift room circuit breakers or

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distribution must be provided by the lift manufacturers. The supply of the lift cage light must be on a separate circuit. It is usual to provide a local distribution board in the lift room and the lights controlled by the switch in the switch room. These cables must be entirely separate from the cables feeding the power supply to the lifts. These lights should be connected to maintained/emergency supply so that in the event of a mains failure, the lights in the lift cage are not affected. Alarm systems should also be connected to a maintained/ emergency supply or from a battery. Cables other than those connected to the lift circuit must not be installed on lift shafts. The lift circuit includes lights for the lift shaft for purposes of maintenance. Cables connected to the lift circuit need not be installed on lift shafts. A lift designated as a fireman’s lift could be on a separate circuit so that in the event of a fire, the supply to this lift is maintained while the supplies are switched off. Otherwise, it could be fed from the main lift riser which in this case the riser should be controlled by a circuit breaker on the main switch board which bypasses the main isolator in the building. NB: The recommended speed for any lift system is approximately 1.6-1.75m/s 2.7 Fire Detection & Alarm System This system is essential in the eventuality of a fire. All buildings have to be fitted with these systems as is required by the various codes and regulations and the relevant governing by-laws in any town, city or country. At the initial stages of the fire detection & alarm system design one has to consult with all the interested parties, i.e. the system installer, the local fire authority, insurance company consultant, etc. This is done to establish the purposes of the system: enhance the safety of the occupants and/or to minimize the damage to property. BS 5839 Part 1 code provides classification to allow specification of system types, by principal purpose and extent of protection provided. 2.7.1 Life protection This describes a satisfactory fire alarm system for the protection of life that can be

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relied upon to sound a fire alarm while sufficient time remains for the occupants to escape. LI All areas covered with detectors except voids less than 500mm in height

(unless the spread of fire between rooms can take place through it) L2 Specified areas where a fire could lead to a high risk to life e.g. sleeping

areas without supervision, areas having a high probability of ignition which could spread to affect building occupants: where occupants are especially vulnerable e.g. old people.

L2 should always cover L3 coverage L3 Protection of escape routes such as:

d Corridors, passageways and circulation areas. d Rooms opening into escape routes. d Top of stairs. d On landing ceilings at vertical intervals not exceeding 10.5 m below the

top of any staircase. d Top of vertical risers such as lift shafts. At each level within 1.5 meters

of access to lift shafts or other vertical risers. This system normally incorporates a manual alarm only. These systems normally include smoke detectors, heat detectors, break-glass push switch complete with conduit and wiring, fire alarm sounder complete with conduit and wiring and the fire alarm annunciator panel complete with alarm buzzer indicator lamps. Heat detectors are mainly used in areas that are prone to smoke e.g. smoking zones, kitchens and even basements. The heat and smoke detectors have a span of 10m. 2.7.2 Property protection A satisfactory fire alarm for the protection of property will automatically detect a fire at an early stage, indicating its location and raise an effective alarm in time to sermon the fire fighting forces {both resident staff and the local town/city council fire brigade}. The general attendance time of the fire brigade should be less than 10 minutes. Therefore an automatic direct link to the fire brigade is essential

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Zoning of the system to ensure a fast and unambiguous identification of the fire source, the protected area should be divided into zones. When determining the area to be covered by a zone, consideration should be given to accessibility, size, and the fire routine determined for the premises and particularly in occupied premises, that each zone is accessible from the main circulation routes leading to where the control panel is sited. Generally, the following guide lines should be observed: d If the total floor area of the building is not greater than 300m2 then the

building needs only one zone no matter how many floors it has. d The total floor area for a zone should not exceed 2000m2. d The search distance should not exceed 30m, i.e. the distance that has to be

traveled by a searcher inside a zone to determine visually the position of a fire should not exceed 30m.

d Where stairwells or similar structures extend beyond one floor but are in one fire compartment, the stairwells should be a separate zone.

d If the zone covers more than one fire compartment then the zone boundaries should follow compartment boundaries.

d If the building is split into several occupancies, no one zone should be split between two occupancies.

NB: A fire compartment is an area bordered by a fire resisting structure usually at least 30 minutes resistance. 2.7.3 Fire Detection and Alarm System Composition It comprises of: d Break glass and manual call point. d Alarm sounders. d Heat detectors. d Smoke detectors. d Control Equipment. d Stand-by power supplies

26

d Wiring

2.7.3.1 Break Glass And Manual Call Points The break glass call point is a device to enable personnel to raise the alarm in the event of a fire, by simply breaking a tangible element and thus activating the alarm system. 1) Break glass call points should be located so that no person needs to travel more

than 30 meters from any position within the premises in order to give an alarm. 2) Generally call points should be fixed at a height l400mm above the floor, at

easily accessible, well illuminated and conspicuous position tree from obstruction.

3) The method of operation of all points in an installation should be identical unless there is a specific reason for differentiation.

4) Manual and automatic devices may be installed on the same system but it is sometimes advisable to have them on a separate zone for speed of identification.

2.7.3.2 Alarm Sounders This is an important component of any fire alarm system. It must be audible throughout the building in order to alert and evacuate the occupants of the whole building. The following are notes guide in design of bells or electronic sounders: 1) A minimum sound level should be either 65dBA or 5dBA above any

background noise likely to persist for a longer period than 30s whichever is greater, should be produced by the sounders at any occupied point in the building.

2) In premises such as boarding houses or hostels the minimum sound level should be 75dBA minimum at the bed-head.

3) Warning devices used in the same system should have a similar sound device and be distinct from other sound alarms.

4) A large number of quieter sounders rather than a few very loud sounders may be preferred to prevent noise levels in some area from becoming too loud.

5) The level of sound should not be so high as to cause permanent hearing damage.

27

2.7.3.3 Heat Detectors Heat detectors are devices that respond to increases in temperature. In general they are less sensitive than other types of detectors and I have used them in areas such as kitchens and the basements. 2.7.3.4 Smoke Detectors In a building the greatest concentration of smoke (and heat) will generally collect at the highest point of the closed area and it is here there that the detectors should be sited. i) Under flat horizontal ceilings and corridors greater than 5m wide Maximum area of coverage = 100m2 Maximum distance covered = 10m (5m to wall, 7.5m for layouts that are not square) ii) In a corridor less than 5m wide. 50% of the difference between 5m and the actual width of the corridor is added to the maximum horizontal distances e.g. in a 3m wide corridor differences between 3m and 5m = 2m. Therefore 50% of 2m = 1m Maximum distances to travel for a point type smoke detector should be 10m + 1m = 11m iii) In the apex of a Pitched Roof. A row of detectors should be sited in the apex. iv) Obstructions Where the passage of smoke or hot gas from a position may be disturbed by a ceiling obstruction, the horizontal distance should be decreased by twice the depth of the obstruction. v) Smoke detectors should be mounted less than 500mm from any walls or partitions. 2.7.3.5 Control Equipment The control and indicating panel depends on the zone circuits, sounder circuits, battery standby and remote center link auxiliary control relays. The considerations

28

that may be taken into account are: 1) In an area of low fire risk 2) On the ground floor by the entrance 3) In the area common to all building users. 4) A full day manned area 2.7.3.6 Stand-By Power Supplies Stand-by supplies will usually be from secondary batteries with automatic changers. The BS code bans the use of car batteries. The stand-by batteries must have an expected life of at least 4yrs. When the main supply fails, the stand-by must be able to operate the alarm load for 30 minutes after a certain minimum duration. 2.7.3.7 Wiring The satisfactory operation of a fire alarm system depends on the interconnection of its components. Some interconnection may have to function correctly for significant periods after being attacked by fire e.g. cables to power supplies, control equipment and sounders. 2.7.3.8 Routine Testing of Systems The system should be regularly tested and serviced in accordance with requirements of BS 5839. As a guide the user should carry out the following tests and inspections at regular intervals. Daily: d Check that the panel indicates normal operation. If not, record any fault

indicated in the event log and report the fault to a responsible person. d Check that any fault recorded for the previous day has received attention.

Weekly d Operate a manual call point or smoke detector to ensure that the system

operates properly. Each week a different detector should be checked. d Check that the sounders have operated then reset the system. d Check the battery connections. d Complete the event log with details of date, time, device tested and enter

29

‘routine weekly tests', the action required and report to a responsible person. Quarterly d Check entries in the log book and take any necessary action. d Examine the batteries and their connections. d Operate a manual call point or smoke detector to ensure the system operates

properly checking that all sounders are operating. d Check all functions of the alarm control panel operating by simulating fault

conditions. d Visually check that structural alternatives have not been made that could

have an effect on the sitting of detectors and other trigger devices. d Complete the event log with details of date, time, trigger device tested and

"quarterly test" in the event section. Any defects or alterations to equipment should also be entered.

Annually d Carry out inspection as detailed for the quarterly inspection. d Every detector should be tested. d All cable fittings and equipment should be checked to ensure that they are

secure and undamaged. Upon completion of the building, the testing and commissioning of the fire detection alarm system is carried out as a necessary requirement by various officers approved for this exercise by the by-laws. Fig 2.5: Example of lightning protection of a building. 2.8.2 Earthing The whole of the earth may be considered as a vast conductor which is at reference

(zero) potential. Thus the term 'earth' or 'ground'. The process of earthing involves

the connection of all the points which could become charged to the general mass of

earth, to provide a path for fault currents and to hold the paths as close as possible

30

to earth potential.

This then prevents a potential difference between earth and earthed parts, as well

as permitting the flow of fault current which cause the operation of the protective

systems. The standards method of tying the electrical supply system to earth is to

remove direct connection between the two. This is usually carried out at the supply

transformer, where the neutral conductor (often the star point of a three-phase

supply) is connected to earth using an earth electrode or the metal sheath and

armoring of a buried cable.

2.7.2.1 Merits of Earthing

1) The whole electrical system is tied to the potential of the general mass of

earth and cannot 'float' at another potential. For example in Kenya we can be

fairly certain that the neutral of our supply is at or near zero volts (earth

potential) and that the phase conductor of our standard supply differs from

earth by 240 Volts.

2) By connecting earth to metal work not intended to carry current (an

extraneous conductive part or an exposed conductive part) by using a

protective conductor, a part is provided for fault current which can be

detected and if necessary broken.

2.7.2.2 Demerits of Earthing

1) The provision of a complete system of protective conductors, an earth

electrode etc is very expensive.

2) It has been argued that complete isolation from earth will prevent shock due

to indirect contact because there is no path for the shock current to return to

the circuit hence earthing may be unnecessary. This argument however

ignores the presence of earth leakage resistance (due to imperfect insulation)

31

and phase-to-earth capacitance (the insulation behaves as a dielectric).

In normal earthing, the earth and the neutral are quite separate. The load current

flowing through the neutral causes a potential difference between the two ends of

the neutral. The consumer's service terminal cannot be used as an earth point as it

is inevitably at some potential above earth.

2.6.2.3 General Requirements of Earthing

Earth Electrodes: To ensure an effective earth for the earth continuity conductor

there is need to for the contractor to provide earth electrodes as instructed in the

specification. An earth electrode is a metal rod which makes effective contact with

the general mass of earth. A common type used in this country consists of a small

diameter copper rod which can be easily be driven to a depth of 6 meters of more

into a ground reasonably free of stones or rock. This illustrated in fig 2.5 above.

The soil remains practically undisturbed and is in very close contact with the

electrode surface. Since resistivity is lower in the deeper strata of the earth and not

very affected by seasonal conditions, deep driving gives a good earth. Rods of this

type are practically incorrigible. It is also easy get access to the connection at the

top of the electrode. If the ground will be found to be shallow and has low

resistivity there will be need to add a plate electrode or mesh. Furthermore, the

surface of the ground near the electrode becomes live when current flows from the

electrode to earth.

Earth wires: A minimum permissible size of earth wires is determined mainly by

the mechanical considerations because they are more liable to mechanical injury

and should therefore be strong enough to resist any strain that is likely to be put on

them. All earth wires and earth continuity conductors should be of copper,

32

galvanized steel or aluminum. In this project copper conductors have been

specified. Interconnections of earth continuity conductors should be in such a way

that reliable and good electrical connections are permanently ensured.

The path of the earth wire should as far as possible be kept out of reach of any

person. If the metal sheath or armor has been used as an earth electrode, the amour

should be bonded to the metal sheath and the connection between the earth and the

earthing electrode should be made to the metal sheath. When proper earthing is

carried out, the risk of shock is prevented as the objective of earthing is to ensure

that a fault to earth produces the same condition as a short circuit between lines

and neutral cables.

33

CHAPTER 3: DESIGN METHODOLOGY 3.1. INTRODUCTION The design of an electrical system in a building is carried out in the following manner:

• Lighting design • Artificial lighting and LV power installation design including computer

connections • Determination of current carrying capacities and voltage drops for cables • Design of fire detection and alarm system • Design of the security system • Design of the lightning protection & earthing system. •

3.2: LIGHTING DESIGN This involves the selection of type of luminaries to be used in the various parts of the building depending on the required illumination levels, functionality of the room and aesthetic values. 3.3: ILLUMINATION The steps involved in computation of the number of luminaries in the various rooms in the building are as follows:

• R.I= L*W___ (Hm*(L+W))

• Where L =Length of room

W =Width of room Hm =Spacing to height ratio (difference between the height of the

room and the height of the working surface or surface of the task, taken to be 0.85m)

• Determination of the effective reflectance of the ceiling cavity, walls and floor cavity

34

• Determination of the utilization factor (U.F) value from the data tables, with reference to the selected luminaries, using the calculated room index and the effective reflectance.

• Quotation of the Maintenance Factor (M.F) is usually based on the environmental conditions. For offices, I used 0.83, the hallways and all other areas 0.8 and all the rooms in the building 0.9

• Insert the appropriate values into the lumen method formula to obtain the number of luminaries (N) as follows:

N= A*E____ F*n*MF*UF

Where: N = Number of luminaries. E=Standard Service I luminance

A = Effective reference surface area. n = Number of lamps per fitting. MF = Maintenance factor UF = Utilization factor F= Initial bare lamp flux. (Obtained from the lamp catalogue)

• Make the necessary designs ensuring that the luminaries are appropriately distributed.

NB: A good lighting system design involves more than calculations. Attention should be paid to human requirements for lighting. 3.4: L.V. POWER INSTALLATION The final sub circuit wiring should be carried out using single core PVC insulated copper cables enclosed in the high compact heavy PVC conduits cast slabs embedded in fabric of building or run on the roof space. All water heaters and outlets for shavers and hair driers are controlled via a 20A DP switch from the local circuit. The cooker control units are flush mounted with 45A DDDP switch socket outlet and neon indicators. The connector boxes for the above equipment are flush molded cover plates. This also includes lets for toilet

35

extract fans, hand driers. 20A SPN isolators are also included for the various equipment that are rated at above 3kW e.g. booster pumps and the washing machines and driers. Provision for air conditioning units was also made in the office floors. All these considerations will be depicted in the actual drawings. 3.5: CURRENT CARRYING CAPACITIES AND VOLTAGE DROPS FOR CABLES. As per BS 6346, table 9D3 gives the current-carrying capacities corresponding to continuous loading. These current ratings are known as the full thermal current ratings. Correction factors are given for the various ambient temperatures in order to obtain the effective current carrying capacity. For my project, I am going to use an ambient temperature of 25○C (whose correction factor is 1.06) since the average temperatures in Nairobi are 23○C as per the metrological data sheets. In practice however, the ambient air temperatures may be determined by thermometers placed in free air close to the installed cables as possible. This temperature does not include heat produced by the cable. Thus if the measurements are made when the cables are loaded, the thermometers must be placed about 0.5m or 10 timed the overall diameter of the cable, whichever is lesser, from the cables, in the horizontal plane, or 150mm below the lowest of the cables. 3.5.1 Determination of current carrying capacity. The effective current carrying capacity is obtained for cables in ducts in the floor of a building. 5.3.2 Determination of size of cable used. This is done after one has established a design current for the circuit under consideration and chosen the type and nominal current (current setting in accordance with Regulation 433-2 of the over-current protective device) it is intended for use, the following procedure is followed:

1. Determine the load current of the building

36

2. Determine the correction factor for ambient temperature which does not include heat generated by cable.

3. Determine the correction factor for grouping (ref Table 9B) of IEE regulations. Since the cable is completely surrounded therefore correction factor is 0.5.

4. Select rating of over-current device. 5. The size of the conductor is then obtained from current rating tables of IEE

regulations. 6. Compute the voltage drop and confirm that it does not exceed maximum

permissible by regulation 522-8 i.e. maximum permissible voltage drop is 2.5% of entire load.

The accompanying computations are shown in the table in the schedules pages. 3.6: FIRE DETECTION & ALARMS SYSTEMS The fire detection and alarm system’s purpose was taken to be:

• to enhance the safety of the occupants and • to minimize the damage to property

It includes the following components: • Break glass and manual call point. • Alarm sounders. • Heat detectors. • Smoke detectors. • Control Equipment. • Stand-by power supplies • Wiring

A 12 zone addressable fire alarm Enunciator Panel complete with alarm buzzer, indicator lamps (LED) as Menvier or approved is to be included and placed in the control room at the basement 1 floor. Smoke detectors and heat detectors as Menvier or approved equivalent wired in fire resistant low voltage cables drawn in 25mm diameter PVC heavy gauge conduits are going to be used. Break glass push switches and fire alarm sounders wired in fire resistant low voltage cables drawn in 25mm diameter PVC heavy gauge conduits wired in fire resistant low voltage cables drawn in 25mm diameter PVC heavy gauge conduits are also used. The entire system has to be incorporated within it the standby power supplies.

37

I will mainly use smoke detectors as they are more sensitive than heat detectors. The heat detectors are however used in moisture and heat prone areas and areas that have a lot of smoke such as kitchens. Their span is normally 10m. There are no computations involved and placement of the detectors and break glass points are based on practical experience. This is however subject to changes after recommendations from the approved contractor. After installation by the approved contractor, testing and commissioning of the system has to be done by the local authorities. 3.7: LIGHTNING PROTECTION & EARTHING issued by the Normally for tall structures not like this one being undertaken in the project, the most economical way of protecting is by use of reinforcement members in the structure. If this isn’t used, the cost of the special down conductor tape or cable represents a major cost of the installation. This is particularly so since several down conductors spaced 30m apart will be required for the building of this magnitude and with test clamps at intermittent points for testing of the system. Steel frame buildings require protection both in terms of roof conductor and earth termination. It is thus not necessary in this case to have any additional down-conductor, provided bonding is ensured to the air terminal and to earth. Where radio and television aerials are located at the highest point of a protected building, the mast and its metal components should be boned by the shortest connection to the roof conductor system. If the receiver is connected by a coaxial cable, the sheath at its highest point, as the television set is normally earthed. The design and implementation of lightning protection has to adhere to the Code of Practice as outlined in the Technical Instruction No. 58 on “Protection of Buildings Against lightning Strokes” Ministry of Works (Electrical Branch), Housing and Planning NB: The lightning protective system has to be designed and implemented to allow ease of testing.

38

3.8: INCOMING & BACKUP POWER SUPPLY Since the scope of my project does also involve design of data ways, I will make allocations for a UPS: But at the moment only a generator. For safety reasons, it is prudent to have the transformer and generator housed outside the main building. The main reasons for housing the generator outside are:

• Acoustics • Noise • Need for proper aeration • Ease in maintenance

The main reasons for having the transformer outside are: • Safety purposes • Ease in maintenance • Cooling

Underground cables have to be provided for connection between the transformer and generator and the switch boards located in the control rooms. For the transformer one has to fill in an “Enquiry for Supply of Electricity” form from KP&LC specifying the type of application, work type, connection type, voltage required and type of premises. This project is a new application, requires HV overhead extension, medium voltage, single phase 415V and three phase underground cables. This form will be accompanied by a breakdown of the appliances, plug points and motors installed in the building. I chose to use an acoustically treated, automatic changeover switch generator so as to minimize the noise levels. The size of the generator was determined by the following method.

• The total wattage of all the lights in a building have to be taken into account and the wattage summed up.

• The total wattage of all the sockets has to also be summed up • The total wattage of all the electrical equipment has to be taken into account

and their wattage summed up. • The total wattage is then converted into volt amperes using a reasonable

power factor. For this project, I will use 0.8.

39

• The various loads are then summed up and a diversity factor taken into account in order to determine the size of the generator load needed for any building.

The generator rating is normally given by the formula:

Generator rating = Total load of the building X Diversity factor I will use a diversity factor of 0.8 as it is within the industrial standards. The diversity factor is the probability that a particular piece of equipment will come on at the time of the facility's peak load. The diversity factor gives us a correction factor to use. If the energy balance we do for this facility comes out within reason, but the demand balance shows far too many kW for the peak load, then we can use the diversity factor to bring the kW into line with the facility's true peak load. The diversity factor does not affect the kWh; it only affects the kW. It is not within the scope of this project to specify all the details of a standby generator as this would otherwise constitute a separate document. The installation of the standby generator will be by a specialist and for this, a Prime Cost sum is allowed in the summary of prices. 3.9: LIFT SYSTEM The main switchgear should be labeled lifts and in the lift room circuit breakers or a distribution must be provided by the lift manufacturers. The supply for the lift cage light must be on a separate circuit. It is usual to provide a local distribution board in the lift room and the lights controlled by the switch in the switch room. These cables must be entirely separate from the cables feeding the power supply to the lifts. These lights should be connected to maintained/emergency supply so that in the event of a mains failure, the lights in the lift cage are not affected. Alarm systems should also be connected to a maintained/emergency supply or from a battery. Cables other than those connected to the lift circuits must not be installed on lift shafts. However, the cables connected to the lift circuit need not be installed on lift shafts. The fireman’s lift is put on a separate circuit so that in the event of fire, the supply to this lift is maintained while the other supplies are switched off.

40

Otherwise it could be fed from the main lift riser in which case, the riser should be controlled by a circuit breaker on the main switch board which bypasses the main isolator in the buildings. Since the local power supply can be erratic and prone to fluctuations and surges, the tenderer shall therefore allow for the necessary protection against power fluctuations and surges. 3.10: SAMPLE CALCULATIONS Given a room of area 174.2m2, to be installed with type A2 luminaries that has lumens of 3750 with 2 lamps in the fitting, the M.F = 0.8 and the U.F = 0.75 the number of luminaries will be as follows: The standard service luminance is 500. The no. of luminaries = 500 x 174.2mm2 3750 x 2 x 0.8 x 0.75 = 19.356 ≈ 20 luminaries Given a load of 3.175kVA with cable length of 10m, the size of cable is: The power is single phase, thus: I = P = 3,175 x 0.8 = 10.5833A V 240 Factoring ambient temperature correction factor, I = 10.5833 x 1.06 = 11.2183A ≈ 12A The recommended size = 1.5mm2 The voltage drop = 29mV x 10m = 0.29V 0.29/3175 = 0.009% which is within the permissible range.

41

CHAPTER 4: RESULTS AND ANALYSIS

Fig. 4.1 Second floor plan

42

Fig. 4.2 Second floor electrical design

43

Fig. 4.3 Sixth floor plan

44

Fig. 4.4 Sixth floor electrical design

45

Fig. 4.5 Seventh floor plan

46

Fig. 4.6 Seventh floor electrical design

47

Key to the drawing

48

4.1 PRICE SCHEDULES NOTES TO TENDERERS ON PRICE SCHEDULES 1. The Tenderer shall complete all schedules except where otherwise instructed.

2. Schedules shall be read in conjunction with other relevant parts of the

Specification as defined herein.

3. The total of prices in the Price Schedules Summary of Prices shall be deemed to

include for the whole of the Sub-Contract Works in accordance with the

Specification. Any prices omitted from any time, section or part of a Price

Schedule shall be deemed to have been included in another item.

4. Attention is drawn to the requirement that the Sub-Contractor will be required

to commence necessary work on site immediately after appointment. The Sub-

Contractor shall tender on this basis and include for purchasing locally such

materials as may be required to execute urgent work to the Main Contractor's

program me.

5. The Sub-Contractor's unit rates as quoted in the Price Schedules for lighting and

socket outlet points etc. shall be deemed to include for all necessary conduit

wiring and lab our.

6. The Sub-Contractor's Unit Rates as quoted in the Price Schedule will be used to

assess the value of additions or omissions arising from authorized variations to

the Contract works.

49

7. The quantities of length of cables, conduits and pipes are approximate but the

Sub-Contractor shall supply and install exact length of each item.

8. If any quantity has not been included in Schedules, the tenderer shall put down

the quantity from their own calculations.

9. The Sub-Contractor shall be required to pay full Import Duty and Value Added Tax (V. A. T.) on all items of equipment, fittings and plant, whether imported or locally manufactured. The tenderer shall therefore make full allowance in his tender for all such duty and tax.

PRICE SCHEDULES MAIN SUMMARY OF PRICES Table 4.1: Lighting and power installation second floor Item Description

Unit

Qty

Rate

KShs.

A. Lighting points wired in 1.5 mm square PVC sc. cables drawn in 20 mm diameter PVC heavy gauge conduits complete with switching as shown on drawings

No

143

630.00

90,090.00

B. The following luminaires complete with rated lamps

Type C2 No 130 700.00 91,000.00 Type L No 60 950.00 57,000.00 C. The following power outlets complete with

wiring as specified:

• 13A twin switched socket outlets wiring in ring using 2.5 mm2 PVC/SC cables drawing in 25 mm diameter PVC heavy gauge conduits

No

20

350.00

10,500.00

• 20 A SPN isolator complete with 4.0 mm2 PVC/SC cables drawn in 38 mm diameter PVC heavy gauge conduits for toilet extractor fan

• 20A DP switches for hand driers

No

No

1

2

1,000.00

1,500.00

1,000.00

3,000.00 • 200 x 50 mm, 3 compartment powder

coated oven baked metal trunking complete with covers, bends etc.

m

150

300.00

45,000.00 TOTAL CARRIED TO COLLECTION PAGE 297,590.00

50

Table 4.2: lighting and power installation sixth floor Item Description

Unit

Qty

Rate

KShs.

A. Lighting points wired in 1.5 mm square PVC sc. cables drawn in 20 mm diameter PVC heavy gauge conduits complete with switching as shown on drawings

No

110

630.00

69,300.00

B. The following luminaires complete with rated lamps

Type C2 No 70 700.00 49,00000 Type J4 No 50 950.00 47,500.00 C. The following power outlets complete with

wiring as specified:

• 13A twin switched socket outlets wiring in ring using 2.5 mm2 PVC/SC cables drawing in 25 mm diameter PVC heavy gauge conduits

• 13A water tight twin switched socket outlets wiring in ring using 2.5 mm2 PVC/SC cables drawing in 25 mm diameter PVC heavy gauge conduits

• Cooker outlets

No

No

No

20

4

4

350.00

400.00

3,000.00

7,000.00 1,600.00 12,000.00

TOTAL CARRIED TO COLLECTION PAGE 186,400.00

51

Table 4.3: lighting and power installation seventh floor Item Description

Unit

Qty

Rate

KShs.

A. Lighting points wired in 1.5 mm square PVC sc. cables drawn in 20 mm diameter PVC heavy gauge conduits complete with switching as shown on drawings

No

84

630.00

52,920.00

B. The following luminaires complete with rated

lamps

Type J4 No 42 950.00 39,900.00 Type C2 No 50 700.00 35,000.00 C. The following power outlets complete with

wiring as specified:

• 13 A twin switched socket outlets wiring in ring using 2.5 mm2 PVC/SC cables drawing in 25 mm diameter PVC heavy gauge conduits

No

9

350.00

3,150.00

• 13 A single switched socket outlets wiring in ring using 2.5 mm2 PVC/SC cables drawing in 25 mm diameter PVC heavy gauge conduits

No

9

250.00

2,250.00

TOTAL CARRIED TO COLLECTION PAGE 133,220.00

52

Table 4.4Fire detection and alarm system ITEM DESCRIPTION

Item

Qty

Rate

KShs

Supply and Install the following complete as specified:

A. 12 zone addressable fire alarm Annunciator Panel complete with alarm buzzer, indicator lamps (LED) as Menvier or approved

No

1

42,780.00

42,780.00

B. Smoke detectors as Menvier or approved equivalent wired in fire resistant low voltage cables drawn in 25mm diameter pvc heavy gauge conduits as follows:

• second Floor No. 12 5,117.00 61,404.00 • sixth Floor No. 10 5,117.00 51,170.00 • seventh floor No. 8 5,117.00 40,936.00

C. Heat detectors as Menvier or approved equivalent wired in fire resistant low voltage cables drawn in 25mm diameter pvc heavy gauge conduit as follows:

• second Floor No. 12 5,200.00 62,400.00 • Sixth floor

• Seventh floor No. No

10 9

5,200.00 5,200.00

52,000.00 46,800.00

D. Break glass push switches wired in fire resistant low voltage cables drawn in 25mm diameter pvc heavy gauge conduits as follows:

• Second Floor No. 4 1,700.00 6,800.00 • sixth Floor No. 4 1,700.00 6,800.00 • seventh Floor No. 4 1,700.00 6,800.00

53

ITEM DESCRIPTION

Item

Qty

Rate

KShs

E Fire alarm sounders wired in fire resistant low

voltage cables drawn in 25mm diameter PVC heavy gauge conduits as follows:

• Second Floor No. 4 2,717.00

10,868.00

• sixth Floor No. 4 2,717.00

10,868.00

• seventh Floor No. 4 2,717.00

10,868.00

F. Testing and Commissioning of the fire detection and Alarm System

Sum

1,650.00

G. Allow for training of users of the installed

system for a period of one week

Sum

5,000.00

H. Any other item necessary to complete the installation in this section

Sum

TOTAL CARRIED TO COLLECTION PAGE

415,494.00

54

Table 4.5: Main voltage switchboard

Item Description Unit Qty Rate KShs.

A Supply and install the Main L. V switchboard complete with all switch gear and accessories.

sum

1,000,00.00 B Allow for the testing and commissioning of

The Main L.V Switchboard complete with the switch gear.

sum

10,000.00 C Allow for earthing of the Main L. V

switchboard. sum 10,000.00

D Include a Provisional Sum of .5000/- for

additional earthing if required. sum 5,000.00

E Allow a provisional sum of KShs. 100,000.00 for the installation of the power factor correction capacitor bank

sum 100,000.00

F Allow for the installation of the power factor correction capacitor bank sum 10,000.00

G Supply and install "Fireman's switch" at the entrance complete with conduit and wiring. No 1 3,000.00 3,000.00

H

Supply and install 2x400mm2 PVC 4 core 3-phase cable from the meter board to the automatic changeover to the main LV switchboard

sum 40,000.00

I Allow for any other item to complete the installation in this section. sum

10,000.00 Total Carried Forward to Main Summary of Prices. 288,000.00

55

CHAPTER 5: DISCUSSION & CONCLUSION Problems Encountered Production of the drawings was a bit problematic as I had to learn how to use AutoCAD for the generation of the model building and other pictures for use. Some difficulties in accessing the I.E.E building services regulations since some have changed with time. I also had to use stipulated codes from other regulatory bodies that are acceptable. Getting various codes from the relevant ministries was also problematic. Access to internet services was costly as such services are not provided in the university. Financial difficulties were experienced since every expense had to come with an accompanying receipt which meant that expenses such as transport for going meetings with various consultants in the building services were not considered.

Recommendations It is a highly recommended for modern multi-functional buildings to adopt this design as it incorporates all the facets in building services especially in higher learning colleges. Design of an intensive computer system has to be done for the project in line with technological advances. Thus a UPS will also come in handy An intricate security system design could be done.

Conclusion

The objectives of the project were achieved as well as the comprehensive understanding of power distribution and illumination systems in the building services sector.

56

REFERENCES Books & Catalogues:

1. Electrical Installation and Workshop Technology Vol. 2 by F.G. Thompson

2. Electrical installation Estimating and Costing Sixth Edition by J.B. Gupta 3. Interior Lighting Design by D.W. Durant 4. IES Code for Interior Lighting 1973 5. Thorn Lighting – Comprehensive product Catalogue 2003/4 6. Thorn Lighting – Comprehensive product Catalogue 1999 7. MK Product Catalogue

Various Standards by Governing Bodies: 1. IEEE Regulation Standards 2. Technical Instruction No. 58 on “Protection of Buildings Against lightning

Strokes” issued by the Ministry of Works (Electrical Branch), Housing and Planning.

3. Technical Instruction No. 58 on “Protection of Buildings Against lightning Strokes” issued by the Ministry of Works (Electrical Branch), Housing and Planning.

4. Extract Table 9D3 (Current carrying capacities and associated voltage drops for twin and multi-core armoured PVC insulated cables (copper conductors)) and Table 9B1 from the IEE BS6346 standards.

Websites:

1. http://home.att.net/~ledmuseum/ 2. http://www.darksky.org 3. http://www.oaklandpw.com

Selected white papers:

1. Kenya Code of practice for the protection of structures against lightning –design aspects by A. W. Ogwayo

2. Protection of Electrical Power systems by Eng. J. W. Njaaga Others:

1. Selected newspaper articles from The Daily Nation, The Standard. 2. Contract and tender documents by Geomax Consulting Engineers act .