ee117-ex-proof installation-th-inst.pdf

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SRI LANKA INSTITUTE OF ADVANCED TECHNOLOGICAL EDUCATION

Training Unit

Ex-Proof InstallationTheory

No: EE 117

ELECTRICAL and ELECTRONIC

ENGINEERING

Instructor Manual


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Training Unit

Ex-Proof Installation

Theoretical Part

No.: EE 117

Edition: 2009Al l Rights Reserved

Editor: MCE Industrietechnik Linz GmbH & CoEducation and Training Systems, DM-1Lunzerstrasse 64 P.O.Box 36, A 4031 Linz / Austr iaTel. (+ 43 / 732) 6987 3475Fax (+ 43 / 732) 6980 4271Website: www.mcelinz.com


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EX-PROOF INSTALLATION

LIST OF CONTENT

CONTENTS Page

1

Introduction to explosion protection for electrical switchgear.........................................3

2 Identification table..........................................................................................................4

3 Degress of explosion protection to prevent the ignition of gases or vapours.................6

4 Identification of equipment.............................................................................................7

5 Regulations on Explosion-Protection.............................................................................8

6 Hazardous areas due to the presence of explosive gases, vapours and mists...........11

7 hazardous areas due to the presence of dust/air mixtures :........................................14

8 Classification of apparatus...........................................................................................15

9 Types of protection according to European standard ..................................................17

10 Marking of explosion-protected apparatus ..............................................................18

11 Degrees of protection in accordance with EN 60529..............................................20

12 installation of electrical equipment in potentially explosive areas ........................... 21

13 Selection of equipment............................................................................................21

14 Application...............................................................................................................22

15 Design .....................................................................................................................22

16 Laying......................................................................................................................22

17 Regulation and approvals outside the EC Jurisdiction............................................23

18

General requirements..............................................................................................26

19 Definitions and symbols ..........................................................................................27

20 Apparatus grouping and temperature classification ................................................31

21 Temperatures..........................................................................................................32

22 Requirements for all electrical apparatus................................................................34

23 Non-metallic enclosures and non-metallic parts of enclosures ...............................35

24 Enclosures containing light metals..........................................................................38

25 Fasteners ................................................................................................................38

26 Interlocking devices.................................................................................................40

27 Bushings .................................................................................................................41

28 Connection facilities for earthing or bonding conductors.........................................41

29 Cable and conduit entries........................................................................................42

30 Flameproof enclosure d ........................................................................................45

31 Flameproof enclosure e ........................................................................................56

32 pressurized enclosure p........................................................................................68


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Introduction to explosion protection for electrical switchgear

During the manufacture, processing, transportation and storage of flammable substances

in the chemical and petrochemical industries, it frequently occurs that gases and vapours

escape and form an explosive atmosphere in combination with the oxygen in the air. If anaccidental ignition of this atmosphere is caused by, for example, sparks from electrical

switchgear, explosions' may occur and cause injury to persons and damage to property. In

order to avoid hazards of this kind, safety measures have been developed in a number of

countries. Due to the increasing number of international links in these industries, it became

necessary to achieve uniform international coordination of these safety measures.

The first organization for international cooperation was the "International Electrotechnical

Commission" (IEC), which was founded in the year 1906 with the objective of preparing

uniform recommendations for the field of electrical engineering.

Today, responsibility for the preparation of European standards lies with the European

Committee for Electrotechnical Standardization. This committee includes representatives

not only of the countries of the European Economic Community but also of Finland,

Norway, Austria, Sweden and Switzerland. European standards are produced by this

committee, the CENELEC, in three official editions (French, English, German).


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1 Identification table

The following table shows a comparison of the identification system for equipment in

accordance with the previous regulations VDE 0170/ 0171/2.61 and the identification

system in accordance with the European standards or the regulations

VDE.0170/0171/5.78:


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1)For definition, see EN 50 014, Appendix A

In order to determine the explosion group (previously known as the explosion class), gases

and liquids are ignited in a vessel with standard properties. An identical type of gas is also

present outside the vessel. The vessel incorporates gaps of adjustable width. The

explosion group (ignition breakdown) with flameproof enclosure d (e.g. with a gap length of

25 mm) is defined by the gap width at which the mixture outside the vessel just fails to

ignite.

The ignition temperature is defined as the lowest temperature of a heated wall at which the

most combustible mixture just ignites (DIN 51 794). In accordance with this, flammable

gases and vapours are classified into temperature classes (previously known as ignition

groups)


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2 Degress of explosion protection to prevent the ignit ion of gases or

vapours

Degree ofexplosionprotection

Symbol Explanation

Increasedsafety

e Special measures are provided to prevent the occurrence of spark,arcs or hazardous temperatures at components at which thesephenomena do not occur in normal operation.

Flameproof d Endangered components are encapsulated in a housing which is ableenclosure to withstand a certain test pressure when a mixture isexploded within this housing, thus preventing the transmission of theexplosion to the mixtures surrounding the housing (ignition-proofencapsulation).

Pressurizedapparatuspreviouslyknown asforcedventilation

p Endangered components are encapsulated in housing which areapparatus scavenged by fresh air or inert gases (protective as forced(f) gas) under pressure in such a way that explosive mixtures whichhave entered the housings before commissioning are removed and areunable to penetrate the housing during operation.

Oil immersion o Endangered components are immersed in oil so that the any explosivemixtures present above the surface of the oil cannot be ignited by arcs,sparks or hot gases produced below the surface of the oil.

Sand filled q Endangered components are immersed in a fine-grained filling materialso that, when the equipment is used for the intended purpose, an arcarising within the housing can not ignite and explosive atmospheresurrounding the housing. Ignition must not be possible, either as theresult of flames or as the result of increased temperatures at thesurface of the housing.

Intrinsic safety i The energy in an electrical circuit is so low that explosive mixturescannot be ignited by sparks caused by the closing or opening of thecircuit.

Un the new VDE regulations, equipment with intrinsically-safe circuitsis classified into toe categories :

ia: Equipment of this category must not be able to cause ignition whenany combination of two faults occurs.

ib: Equipment of this category must not be able to cause ignition whenone fault occurs.

Special

protection

s This is at present valid only of equipment constructed in accordance

with VDE 0171/2.61. There are no design regulations for this degree ofexplosion protection. The occurrence of an explosion is prevented bymeasures other than those described above. A test by the relevantofficial testing body must demonstrate that the selected method ofprotection is adequately effective.


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3 Identification of equipment

The European standards specify an identification method for explosion-proof electrical

equipment. Electrical equipment with the degree of explosion protection "Flameproof

enclosure" could, for example, have the identification EEx d II B T3. This identification is

mandatory for all equipment, no matter whether it is intended for sale only within the

European Economic Community or. also outside. If the equipment is also awarded an EEC

certificate (conformity or inspection certificate), it is further marked with the symbol Ex. The

complete designation for certificated equipment with the degree of explosion protection

"Flameproof encapsulation" would then be as follows:

Examples of identification for explosion-proof electrical equipment:

Degree of explosion protection of

equipment

Identification in accordance with EN 50

014 50 020

Increased safety EEX e II T4

Flameproof enclosure EEX d II C T5

Intrinsic safety (EEX ia) II C+)

or (EEX ib) I C

+)Intrinsically-safe circuits of category is may enter zone 0. All equipment for zone 0 must,

however, be certificated.


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4 Regulations on Explosion-Protection

Electrical apparatus for use in hazardous areas must be explosion-protected in design and

must comply with the regulations on Explosion-Protection. In order to establish a

requirement and safety level that is the same throughout Europe the EC Commission has

compiled product-related European Directives for all types of products.

In 1975 the Council of the European Community issued basic directives on Explosion-

Protection. These were converted into national law in Germany in the "Regulators

concerning electrical installations in explosive atmospheres(Elex V)" issued in February,

1980. CENELEC the European committee for electrotechnical standardization, worked out

European standards for apparatus for use in hazardous areas. These standards DIN

EN50014 to 50020/VDE 0170/0171, Parts 1 to 7, designated as VDE regulations, cameinto force on 1.5.1978. They contain constructional and test requirements for explosion-

protected electrical apparatus for Zone 1

The certificates of conformity or inspection certificates issued by notified bodies of member

states of the EC. which are issued on the basis of the tests carried out. are recognized by

all member states of the European Union as type examination certificates.

Explosion-protected apparatus according to the directive 76/117/EEC bear

the Ex-symbol.

After a transition period as of July 1. 2003 the directives 94/9 EC of the European

Parliament and Council for the harmonization of the statutory previsions of member states

on apparatus and protective system intended for use potentially explosive atmospheres

dated 23.3.1994 (directive 94/9/EX) will replace any existing directives on Explosion-

Protection on a European level.

This new Ex-directive was converted into national German law by the new "Explosion

Protection decree (ExVO)" issued in December 1996.

Parallel to this a revised version of the "Regulations concerning electrical installations in

explosive atmospheres (ElexV)" was also issued in December 1996.


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Among other things. the new ATEX directive slates the classification and marking of

apparatus for use in hazardous areas. Apparatus is now classified as:

Apparatus for mining

operations: Apparatus Group I

Apparatus for use in all other

Hazardous areas Apparatus Group II


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This is divided further into apparatus categories that regulate the safety level of the

apparatus for In the respective zone :

Categories 1, 2 and 3

In addition to this, distinction is also made between apparatus for use in hazardous areas

due to the presence of explosive gases, vapours or mists, code letter "G", and apparatus

for use in hazardous areas due to the presence of dust, code letter "D".

Apparatus for hazardous areas with the

presence of explosive gases, vapours or mists

Zone Apparatus category Marking

0 1 II 1G

1 2 II 2 G

2 3 II 3 G

Apparatus for use in hazardous areas caused by dust

Zone Apparatus category Marking

20 1 II 1D

21 2 II 2 D

22 3 II 3 D

After successful completion of the type test within the scope of the conformity evaluation

procedure, the authorized testing stations, now called notified bodies, issue an EC Type

Examination Certificate.

To fulfil all requirements of the Explosion-Protection directive 94/9/EC (as well as of any

further EC-directives which is applicable), the manufacturer issues an "EC Declaration ofConformity".

To allow free movement of goods throughout the CE marking

shall be affixed to all apparatus to which this EC declaration of conformity applies.


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5 Hazardous areas due to the presence of explosive gases, vapours and

mists

Hazardous areas due to the presence of explosive gases, vapours and mists are classified

into three zones. This classification depends on the probability of the occurrence of anexplosive gas atmosphere.

What electrical apparatus may be used in the individual zones?

Zone 0 covers areas in which an explosive atmosphere caused by a mixture of air and

gases, vapours or mists is present continuously, for long periods or frequently.

Zone 0 mainly encompasses the areas inside closed containers, pipelines and apparatus

which contain inflammable liquids. The respective operating temperature lies above the

these flash point. The hazardous area is above the liquid level and not within the liquid.

With apparatus in the category 1 G (for Zone 0), in order to avoid ignition hazards resulting

from electrical circuits of the apparatus it is necessary to guarantee the specified degree of

safety.

- in the event of two independent faults when only one protection measure is applied or

- in the event of the failure one protection measure by means of a second independent

protective measure.

These conditions are deemed fulfilled if, for cases only e.g. the surroundings of outdoor

example the apparatus

- is designed in the type of protection ia" to EN 50020 or

- intrinsically safe apparatus to "ib" is also potted according to EN 50028.

The requirements on apparatus with regard to electrostatic charges are considerably

higher than those for Zone 1 or Zone 2.

The constructional and testing requirements for electrical apparatus in apparatus Group II

1 G have been newly regulated in Europe. EN 50284 / VDE 0170/0171, Part 12 replaces

special national arrangements as defined by the ATEX directive.


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Zone 1 covers areas in which the occasional occurrence of an explosive atmosphere due

to the presence of gases, vapours or mists is likely.

Inflammable or explosive substances are made, processed or stored in Zone 1. This

includes the area surrounding charging doors, the immediate vicinity of filling and emptying

devices, the immediate vicinity of fragile equipment and lines. as well as around cable

glands on pumps and slides that do not seal adequately. The occurrence of an explosive

atmosphere is likely during normal operation.

With apparatus of the category 2 G (for Zone 1 ). it is either necessary to ensure that the

occurrence of an ignition source is excluded or the ignition source must be encapsulated

by a recognized type of protection in such away that the ignition of an explosive

atmosphere surrounding the apparatus is prevented. This applies in Zone 1 for both

normal, trouble-free operation and for the operating faults that commonly occur. The

constructional and test regulations for the permissible types of protection are laid down in

EN 50014 ff. The table on page 0/6 is a comparison of these types of protection for Zone 1

apparatus.

Zone 2 covers areas in which the occurrence of an explosive atmosphere due to the

presence of gases. vapours and mists is not likely. but if one should occur. then only rarely

and only for a short period.

Zone 2 encompasses areas around Zones 0 and 1 and areas around flanged joints of

pipelines in closed rooms. Furthermore, it includes areas in which, due to natural or forced

ventilation, the lower explosion limit is reached in exceptional.

Inflammable or potentially explosive materials are made and stored in Zone 2. In such a

way that the probability of the occurrence of an explosive atmosphere is rare. and then

only for a short time.

Apparatus in the category 3 G zone 2) must be designed in such a way that it is safeduring normal trouble-free operation. All apparatus that fulfils the requirements for Zone 0,

Zone 1 and Zone 2 may be used. The requirements for electrical apparatus specially

designed for use Zone 2 have been newly regulated - EN 50021. In future the previous

practice of also using apparatus of "good industrial quality in Zone 2, a common practice

in some countries, will not be possible without additions. Zone 2 apparatus to EN 50021


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provides a level of protection that is considerably higher than that of standard industrial

apparatus.

Similarly in the new standard, the requirements for Zone 2 apparatus according to previous

national standards are considerably higher.

The type of protection "n" applies for Zone 2 apparatus: apparatus that cannot ignite a

surrounding explosive atmosphere under normal and certain abnormal operating

conditions. In addition to this, distinction is made between apparatus that does normally not

produce arcs sparks and/or hot surfaces "non-sparking apparatus" and apparatus that

produce sparks/arc and/or hot surfaces "sparking apparatus". The Explosion-Protection

methods resulting from this were derived in part, from the types of protection for Zone 1

/category 2 apparatus whereby they were adapted for Zone 2/category 3 apparatus on a

lower level.

Non-sparking apparatus "nA":

The risk of the occurrence of sparks arcs and or hot surfaces during normal operation is

minimized by constructional measures.

Sparking apparatus:

Here sparks/arcs and/or hot surfaces occur during normal operation: The following

protection methods are permissible:

Apparatus with protected contacts: "nC"

This includes enclosed switchgear, non-ignitable components, hermetically sealed, sealed

and encapsulated devices.

Restricted breathing apparatus: "nR"

Apparatus with simplified pressurization: "nP"

Limited power apparatus: "nL"


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6 hazardous areas due to the presence of dust/air mixtures :

Hazardous areas due to the presence of inflammable dust/air mixtures are also subdivided

into 3 zones that are comparable to the zones for explosive gas atmospheres.

Zone 20 covers areas in which an explosive atmosphere due to dust. air mixtures is

present continuously, for long periods or frequently.

If these conditions occur they are usually found in closed containers, pipelines apparatus

etc.

Zone 21 covers areas in which the occurrence of an explosive atmosphere due to dust air

mixtures is to be expected occasionally.

This can for example, include areas in the immediate vicinity of dust extraction or filling

stations and areas where dust deposits can occur and can form a potentially explosive

concentration of inflammable dust mixed with air under normal operating conditions

Zone 22 covers areas in .which the occurrence of an explosive atmosphere due to

dust is not likely, but, if it occurs then in all probability only rarely and only for a short

period.

This can. for example, include areas in the vicinity of apparatus containing dust if dust can

escape from leaks.

In future only apparatus that fulfils the conditions of the directive 94/9/EC shall be used in

these areas. Electrical apparatus in the type of protection "dust Explosion-Protection due to

enclosure must be built and tested in accordance with EN 50028-1-1, whereby for the

most part this was based on the general requirements in accordance with EN 50014 for

explosion-protected apparatus for gases vapours and mists.

With such dust explosion-protected apparatus, there are, among other things, given

surface temperatures and minimum IP degrees of protection required.

The approval amendments for dust Explosion-Protection in accordance with directive

94/9/EC are already available for many of the explosion-protected light fittings and

apparatus in this catalogue, or they have been applied for.


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7 Classification of apparatus

In accordance with the various properties of gases with regard to ignition temperature.

ignition capability and flame transmission capacity, explosion-protected electrical

apparatus is divided into explosion groups and temperature classes.

Division of explosion-protected apparatus into explosion groups

To specify, the scope of application of explosion- protected electrical apparatus, it is sub-

divided into two groups

Group I: Electrical apparatus for use in mines susceptible to the hazard of firedamp

Group II Electrical apparatus for use in all other hazardous areas

A further sub-division of the Explosion Group II into A", B and "C" is prescribed for the

types of protection "flameproof enclosure" and "intrinsic safety".

With the type of protection "flameproof enclosure this sub-division is made according to

the maximum experimental safe gap for the non-transmission of an internal ignition

(MESG). whereas with the type of protection intrinsic safety" this sub-division is made

according to the ratio of the minimum ignition current of the mixture being tested to the

minimum ignition current of a mixture of laboratory methane and air (MIC). Group II C

apparatus is suitable for use in all types of gas atmospheres.

Division of explosion-protected apparatus into temperature classes

The ignition temperature is the lowest temperature of a surface at which an explosive

atmosphere will ignite. Gases and vapours can be divided into temperature classes

according to their ignition temperatures. This results in a sub-division of explosion-

protected electrical apparatus into the temperature classes T1 to T6. This classification

allows explosion-protected apparatus to be used economically.The maximum surface temperature of an apparatus must always be lower than the ignition

temperature of the gas/air or vapour/air mixture.

Generally speaking, explosion-protected apparatus must be suitable for an ambient

temperature from -20 C to +40 C.


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The following tables show both the division of explosion-protected apparatus according to

the temperature classes and examples of the classification of gases and vapours in

accordance with the explosion groups and temperature classes.

Temperature class Max. sur face

temperature

T1 450 C

T2 300 C

T3 200 C

T4 135 C

T5 100 C

T6 85 C

Classification of gases and vapours into explosion groups and temperature classes

T1 T2 T3 T4 T5 T6I MethaneII A Acetone, Ethane, Ethylalcohol Petrol Acetalde

hydeEthylacetate, Ammonia, i-amylacetate Diesel-

fuelEthyl-ether

Benzol, Acetic acid, n-butane Aviation-fuel

Carbonmonoxide n-butylalacohol Heating-oils,

Methanol, Propane,Toluene

n-hexane

II B Town gas (lamp gas) EthyleneII C Hydrogen Acetylene Carbondis

ul-phide


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8 Types of protection according to European standard

Type ofProtection

Symbol IEC/EN Principle Applications

Power-operated apparatusFlameproof d IEC60079-1

switchgear, motors

enclosure EN 50018 (all types of apparatusproducingignitable arcs innormal operation)

Sand q IEC60079-5

Capacitors, electronic

filling EN 50017 components, fuses

Pressuri- p IEC60079-2

Power-operated apparatus

zation EN 50016 (active safety measuresrequired)

Oil o IEC60079-6

Transformers (rarely used)

immersion EN 50015

Encap- m IEC60079-18

Measurement and control

sulation EN 50028 devices, relays, electroniccircuits

Connection anddistribution

Increased e IEC60079-7

boxes, light fittings,measuring

safety EN 50019 instruments, squirrel cagemotors (no ignitablesparks in

Normal operation)

Intrinsic i IEC60079-11

Measurement and control

safety En 50020 devices, data processing(lowelectric values)


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9 Marking of explosion-protected apparatus

As, until the transition period expires, both the previous basic Explosion-Protection

directive 76/117/EEC, supplemented by the individual Explosion-Protection directive

79/196/EEC, and the new Explosion-Protection directive 94/9/EC are valid, there are twovalid parallel certification procedures and marking methods for explosion-protected

apparatus.

By way of example, the two type labels for an explosion-protected light fitting for

fluorescent lamps show both the marking according to the previous directive and the

marking according to the new directive.

T e label accordin to new directive 94 09/EC

T e label accordin to revious directive


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Name / Code of manufacturer

Type code

Address of manufacturer

Year of manufacture

Community marking for explosion-protected apparatus in accordance with

directive76/117 EEC

Marking of apparatus in accordance w to directive 94/9/EC:

for use in hazardous areas: II

apparatus Group II for use in Zone 1 areas category: 2

for use in gas hazardous areas: G

CE marking confirming conformity with al requirements of the applicable directives

for the product. The number next to the CE marking (only typical for ATEX) stands

for the notified body involved in the production quality system (in this case PTB)

Testing station (notified body) and number of certificate (X" after number means

that special conditions must be observed)

Marking of apparatus in accordance with the European Standards for the

construction and testing of explosion -protected apparatus :Eex: built and tested according to the European Standards

e d: types of protection used according to the European Standards

II C: explosion group

T 4: temperature class

Serial number

Technical data


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10 Degrees of protection in accordance with EN 60529

Because they are often used in outdoor installations and often come into contact with dust

and water as well as with other environmental influences caused by chemical media,

explosion protected electrical apparatus are subjected to particularly extreme operating

conditions in accordance with the constructional and test requirements explosion-protected

apparatus must therefore, satisfy the requirements for a minimum degrees of protection,

normally IP 54. The IP degrees of protection according to EN 60529 are defined according

to the protection against inadvertent contact foreign matter and water.

The degrees of protection against solid foreign matter are designated o the first code

number

Degrees of protection against water are designated by the second code number

Example: IP 65: dust-tight protected against jet water

First Degree of Protection Second Degree of Protection

Number Number

0 No special protection 0 No special protection

1 Protected against solid foreign 1 Protected against vertically

bodies 50 mm and larger dripping water

2 Protected against solid foreign 2 Protected against dripping water when

bodies 12.5 mm and larger The enclosure is inclined up to 15C

3 Protected against solid foreign 3 Protected against spray water being

bodies 2.5 mm and larger sprayed at an angle up to 60

4 Protected against solid foreign 4 Protected against splash water from

bodies 1 mm and larger any direction

5 Dust protected 5 Protected against jet water from any

direction

6 Dust-tight 6 Protected against powerful water jets

from any direction

7 Protected against water when the enclosure

is immersed in water for a specified time

8 Protected against water when the enclosure

is continuously submerged


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11 installation of electrical equipment in potentially explosive areas

Electrical equipment should as far as possible be installed outside explosive areas. In

cases where installation is carried out within such areas, it should be noted that heavy

gases and vapours collect chiefly on the floor, while light gases and vapours collect on theceiling. There is the risk that the vapours of flammable liquids will form clouds, which are

explosive, even at a considerable distance from their point of origination.

12 Selection of equipment

Electrical equipment for installation within potentially explosive areas must be selected in

accordance with the relevant. hazard zone, the flammable gases and vapours which may

be encountered and the mechanical, chemical and thermal influences which may be

present. The mechanical strength of explosion-proof electrical equipment is generally

demonstrated by means of an impact test, in which a 1 kg weight is allowed to fall on to

each type of equipment from a height of 0.7 m The chemical resistance of the equipment

depends principally on the types of aggressive liquids, gases and vapours which are

encountered.

Installation work in potentially explosivee areas must be carried out with particular care.

The properties of the degree of explosion protection must not be impaired by the

introduction of cables into explosion-proof equipment. Care must be taken to ensure a

perfect seal. The rubber rings of the cable glands must correspond to the diameter ,of the

cable. Trumpet-shaped connectors with strain relief should be used to connect flexible

cables.

Trumpet-shaped connector with strain relief

Unused cable penetrations must be correctly sealed in such a way that they can be

opened only by means of tools. Connection blocks must not be used.


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13 Application

Metal conduits are used to lay both individual cables and sheathed cables. These conduits

can be laid on, in and under plaster.. They can also be laid in concrete. Metal conduits

must not be laid under ground.

14 Design

These conduits are thin-walled steel tubes (wall thickness approx. 1 - 2 mm, depending on

diameter), and are supplied in lengths of 3 m. The size designation is derived from the

previously customary types of metal conduit, with internal insulation. The conduit size andthread are defined by the designation Pg 9 - 11 - 13.5 - 16 to 48. Pg 16, for example,

corresponds to an internal conduit diameter of 19.9 mm and external conduit diameter of

22.5 mm.

15 Laying

The conduits should be clamped into a pipe vice, cut to length with a hacksaw and

deburred (file, triangular scraper). A pipe threading die should then be used to cut a thread

at the end of the conduit after chamfering this somewhat.

The conduit lengths of bends should be screwed together by means of threaded sleeves,

and should butt together within the sleeves. Excessively-long threads should be avoided.

Conduit ends which are not fed into boxes or switchgear should be fitted with end bushes.

Metal conduits can be combined with flexible steel tubing, e.g. to allow the connection of

vibrating equipment. On plaster, the conduits should be secured by means of single-strap

or double-strap conduit clamps; in the case of open laying, the conduits should be secured

by means of spacer clamps.


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The distance between clamps should be 80 to 120 cm, depending on the conduit diameter.

In general, the first clamp should be positioned 10 cm after boxes, switches or conduit

ends.

16 Regulation and approvals outside the EC Jurisdiction

Outside the jurisdiction of directive 94/9/EC (EC area) there are other standards and

approvals that apply for the operation of electrical apparatus for use in hazardous areas.

National approvals on the basis of the EN directives

The majority of the eastern European countries such as Russia, Poland, Hungary. etc.

have their own certification bodies that issue their own approvals on the basis of the

current EC type examination certificates. These are requisite for the installation and opera:on of electrical apparatus in hazardous areas in these countries. CEAG Sicherheitstechnik

GmbH is in possession approvals for the products listed in this catalogue in many of these

countries. Details of this can be found at the beginning or end of the product chapter.

Non-European approvals

In addition to the EN standard, the IEC as a worldwide standard is an important basis for

the approval of explosion-protected apparatus. A comparison shows the similarity of

content to the European standards. Thus. almost all of the EC standards can be compared

to EN standards that say the same or are similar in content. Approvals to the "Australian

Standard AS can, for example, be classed with the IEC circle.

Explosion-Protection in North America

The IEC/EN approach to Explosion-Protection differs to the engineering practices in North

America. Here. to name one example, they use closed conduit systems with potted ignition

barriers. Other criteria also apply for the classification. In addition to the

"hazardous(classified) locations" Class I (gases, vapours and mists), there are Class II

(dusts) end Class III (fibres). These design regulations and classifications are laid down inthe NEC Sections 500 to 505. valid for the of USA. and in the CEC standard, Section 18.

valid for Canada. In addition to this the areas are divided into Division 1 and Division 2.

Due to the introduction of the IEC zone classification concept in Canada in 1988 and in the

USA in 1996 (amendment of NEC. Article 505 and of CEC). the use of a comparable

technology became, possible.


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Table of comparison of Type of Protection

Type of Protection EX Standards IEC Standards

General requirements EN 50014 IEC 60 079-0

increased safety e EN 50019 IEC 60 079-7

Flameproof

enclosure d EN 50018 IEC 60 079-1

instrinsic safety i EN 50020 IEC 60 079-11

Oil immersion o EN 50015 IEC 60 079-6

Pressurization p EN 50016 IEC 60 079-3

Powder filling a EN 50017 IEC 60 079-5

Encapsulation m EN 50028 IEC 60 079-18

Type of protection n EN 50021 IEC 60 079-15


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Table of Comparison IEC NEC CEC Classification

Gases, vapours or mists

Class I

Dust s

Class II

Fibres

Class III

Regulation USA NEC 500-5 NEC 505-7 NEC 500-6 NEC 500-7

Regulation

Canada

CEC J18-

004

CEC 18-006 CEC 18-008 CEC 18-010

Classificat ion Division 1 Zone 0 Division 1 Division 1

Zone 1

Group Division 2 Zone 2 Division 2 Division 2

(Groups to NEC

500 ..

-3 -7 -3

or CEC J18-050

Div. 1 and 2 Zone 0, 1, 2 Div. 1 and 2

A(Acetylene)

II C (acetylene,hydrogen)

E (metals) ---

B (hydrogen) II B (ethylene) F (coals)

C (ethylene) II A (propane) G (grain)

D (propane)

Temperature

classes

Class I Div. 1 and 2 Zone 0.1 and 2 Div. 1 and 2 None

T1450C T1450C T1450C

T2300C T2300C T2300C

T2A280C;

T2B260C

T2A280C;

T2B260C

T2C230C;

T2D215C

T2C230C;

T2D215C

T3200C;

T3A180C

T3200C T3200C;

T3A180C

T3B165C;

T3C160C

T3B165C;

T3C160C

T4135C;

T4A120C

T4135C;

T4A120C

T5100C T5100C T5100C

T685C T685C T685C


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17 General requirements

18.1 The IEC (International Electrotechnical Commission) is a worldwide organization for

standardization comprising all national electrotechnical committees (IEC National

Committees). The object of the IEC is to promote international co-operation on all

questions concerning standardization in the electrical and electronic fields. To this

end and in addition to other activities, the IEC publishes International Standards.

Their preparation is entrusted to technical committees; any IEC National Committee

interested in the subject dealt with may participate in this preparatory work.

International, governmental and non-governmental organizations liaising with the

IEC also participate in this preparation. The IEC collaborates closely with the

International Organization for Standardization (ISO) in accordance with conditions

determined by agreement between the two organizations.

18.2 The formal decisions or agreements of the IEC on technical matters express, as

nearly as possible, an international consensus of opinion on the relevant subjects

since each technical committee has representation from all interested National

Committees.

18.3 The documents produced have the form of recommendations for international use

and are published in the form of standards, technical reports or guides and they are

accepted by the National Committees in that sense.

18.4 In order to promote international unification, IEC National Committees undertake to

apply IEC International Standards transparently to the maximum extent possible in

their national and regional standards. Any divergence between the lEC Standard

and the corresponding national or regional standard shall be clearly indicated in the

latter.

18.5 The IEC provides no marking procedure to indicate its approval and cannot berendered responsible for any equipment declared to be in conformity with one of its

standards.

18.6 Attention is drawn to the possibility that some of the elements of this International

Standard may be the subject of patent rights. The IEC shall not be held responsible

for identifying any or all such patent rights.


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18 Definit ions and symbols

For the purpose of this part of IEC 60079, the following definitions apply :

19.1 Electrical apparatus

Items applied as a whole or in part for the utilization of electrical energy. These

include, among others, items for the generation, transmission, distribution, storage,

measurement, regulation, conversion and consumption of electrical energy and

items for telecommunications

19.2 Potentially explosive atmosphere

An atmosphere which could become explosive (the danger is a potential one)

19.3 Explosive gas atmosphere

A mixture with air, under atmospheric conditions, of flammable substances in the

form of gas, vapour or mist, in which, after ignition, combustion spreads throughout

the unconsumed mixture

19.4 Explosive test mixture

A specified explosive mixture used for the testing of electrical apparatus for

potentially explosive atmospheres

19.5 Ignition temperature of an explosive gas atmosphere

The lowest temperature of a heated surface which, under specified conditions

according to IEC 60079-4, will ignite a flammable substance in the form of a gas or

vapour mixture with air

19.6 Service temperature

The temperature reached when the apparatus is operating at its rating

19.7 Maximum service temperature

The highest value of the service temperatures

NOTE - Each apparatus may reach different service temperatures in different parts.


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19.8 Maximum surface temperature

The highest temperature which is attained in service under the most adverse

conditions (but within the recognized tolerances) by any part or surface of an

electrical apparatus, which would be able to produce an ignition of the surrounding

explosive atmosphere

NOTE 1 - The manufacturer will prescribe the product standard and also, in his particular

design, he should take into account the following other conditions:

- fault conditions specified in the standard for the type of protection concerned;

- all operating conditions specified in any other standard specified by him including

recognized overloads;

- any other operating condition specified by him.

NOTE 2 - The relevant surface temperature may be internal or external depending upon

the type of protection concerned

19.9 Enclosure

All the walls, doors, covers, cable entries, rods, spindles, shafts, etc., which

contribute to the type of protection and/or the degree of protection IP of the

electrical apparatus

19.10 Type of protection

The specific measures applied to electrical apparatus to avoid ignition of a

surrounding explosive atmosphere

19.11 Degree of protection of enclosure (IP)

A numerical classification according to IEC 60529 preceded by the symbol IP

applied to, the enclosure of electrical apparatus to provide for

- protection of persons against contact with or approach to live parts and against

contact with moving parts (other than smooth rotating shafts and the like) inside

the enclosure,- protection of the electrical apparatus against ingress of solid foreign objects

and, where indicated by the classification,

- protection of the electrical apparatus against harmful ingress of water.

NOTE - The enclosure which provides the degree of protection IP is not necessarily

identical to the apparatus enclosure for the types of protection listed in clause 1.


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19.12 Rated value

A quantity value assigned, generally by the manufacturer, for a specified operating

condition of a component, device or apparatus

19.13 Rating

The set of rated values and operating conditions

19.14 Cable entry

A device permitting the introduction of one or more electric and/or fibre optics

cables, into an electrical apparatus so as to maintain the relevant type of protection

19.15 Ex cable entry

A cable entry tested separately from the apparatus enclosure but certified as an

apparatus and which can be fitted to the apparatus enclosure during installation

without further certification

19.16 Conduit entry

A means of introducing a conduit into an electrical apparatus so as to maintain the

relevant type of protection

19.17 Compression element

An element of a cable entry acting on the sealing ring to enable the latter to fulfil its

function

19.18 Clamping device

An element of a cable entry for preventing tension or torsion in the cable from being

transmitted to the connections

19.19 Sealing ring

A ring used in a cable or conduit entry to ensure the sealing between the entry and

the cable or conduit

19.20 Terminal compartment

A separate compartment or part of a main enclosure, communicating or not with the

main enclosure, and containing connection facilities


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19.21 Connection facilities

Terminals, screws or other parts, used for the electrical connection of conductors of

external circuits

19.22 Bushing

An insulating device carrying one or more conductors through an internal or

external wall of an enclosure

19.23 Ex component

A part of electrical apparatus for potentially explosive atmospheres, which is not

intended to be used alone in such atmospheres and requires additional certification

when incorporated into electrical apparatus or systems for use in potentially

explosive atmospheres

19.24 Symbol "X"

Symbol used as a suffix to a certificate reference to denote special conditions for

safe use

3.25

19.25 Symbol "U"

Symbol used as a suffix to a certificate reference to denote an Ex component

NOTE - The symbols X and U should not be used together.

19.26 Certificate

A document confirming that the apparatus is in conformity with the requirements,

the type tests and, where appropriate, the routine tests in the standard referred to

therein. A certificate can relate to an Ex apparatus or an Ex component

NOTE - A certificate may be produced by the manufacturer, me user, or a third party, for

example, an IEC Ex accepted certification body, a national certification body. or anauthorised person.


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19 Apparatus grouping and temperature classification

Electrical apparatus for potentially explosive atmospheres is divided into the following:

Group I: electrical apparatus for mines susceptible to firedamp;

Group II: electrical apparatus for places with a potentially explosive atmosphere, other

than mines susceptible to firedamp.

Electrical apparatus intended for mines where the atmosphere, in addition to firedamp,

may contain significant proportions of other flammable gases (i.e. other than methane); it

shall be constructed and tested in accordance with the requirements relating to Group I

and also to the` subdivision of Group II corresponding to the other significant flammable

gases. This electrical apparatus shall then be marked appropriately (for example 'Ex d I/lIBT3' or 'Ex d I/II (NH3)')

20.2 Electrical apparatus of Group It may be subdivided according to the nature of the

potentially explosive atmosphere for which it is intended.

20.2.1 For the types of protection flameproof enclosure 'd', and intrinsic safety 'i', electrical

apparatus of Group II is subdivided into IIA, IIB and IIC as required in the specific

standards concerning these types of protection.

NOTE 1 - This subdivision is based on the maximum experimental sate gap (MESG) for

flameproof enclosures or the minimum ignition current (MIC) for intrinsically safe electrical

apparatus (see annex A).

NOTE 2 - Apparatus marked 118 is suitable for applications requiring Group IIA apparatus.

Similarly, apparatus IIC is suitable for applications requiring Group HA or Group lie

apparatus.

20.2.2 For all types of protection, apparatus of Group II shall be marked as a function of its

maximum surface temperature according to 5.1.2.

20.3 The electrical apparatus may be tested for a particular explosive atmosphere. In

this case, it shall be certified and marked accordingly.


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20 Temperatures

21.1 Maximum surface temperature

21.1 For electrical apparatus of Group l, the maximum surface temperature shall be

specified in relevant documentation according to 23.2.

This maximum surface temperature shall".

- 150 C on any surface where coal dust can form a layer;

- 450 C where coal dust is not expected to form a layer (for example due to sealing or

ventilation), provided that

a) the actual maximum surface temperature is marked on the apparatus, or

b) the symbol X is placed after the certificate reference to indicate the conditions forsafe use.

NOTE - When choosing electrical apparatus of Group 1. the user should take into account

the influence and the smouldering temperature of coal dusts if they are likely to be

deposited in a layer on surfaces with temperatures above 150 C.

21.1.2 Group 11 electrical apparatus shall be arranged and marked according to 27.2 f)

and shall be

- either preferably classified in a temperature class given in table 1;

- or defined by the actual maximum surface temperature;

- or, if appropriate, restricted to the specific gas for which it is intended.

Table 1 - Classif ication o f maximum surface temperatures for

Group II electrical apparatus

Temperature Maximum surface temperatureC

T1 450

T2 300

T3 200

T4 135

T5 100

T6 85


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21.2 Ambient temperatures

Electrical apparatus shall normally be designed for use in the ambient temperature

range between -20 C and +40 C; in this case, no additional marking is necessary.

When the electrical apparatus is designed for use in a different range of ambient

temperatures, it is considered to be special; the ambient temperature range shall

then be stated by the manufacturer and specified in the certificate; the marking shall

then include. either the symbol Ta or Tamb together with the special range of

ambient temperatures or, if this is impracticable, the symbol X shall be placed after

the certificate reference, according to 27.2 i) (see table 2).

Table 2 - Ambient temperatures in service and additional marking

Electrical apparatus Ambient temperature in service Additional marking

Normal Maximum : +40 C None

Minimum : -20 C

Special Stated by the manufacturer and Ta or Tamb

Specified in the certificate with the special range, for

example : -30 C Ta +40 C

or the symbol X

21.3 Surface temperature and ignition temperature

The lowest ignition temperature of the explosive atmospheres concerned shall be

above the maximum surface temperature. However. for components having a total

surface area of not more than 10 cm2, their surface temperature may exceed that

for the temperature class marked on the electrical apparatus for Group 11 or the

corresponding maximum surface temperature for Group I, if there is no risk of

ignition from these components, with a safety margin of

- 50 K for T1, T2 and T3;

- 25 K for T4, T5 and T6 and Group I.

This safety margin shall be ensured by experience of similar components or by

tests of the electrical apparatus itself in representative explosive mixtures.


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NOTE - During the tests, the safety margin may be provided by increasing the ambient

temperature.

More specific relaxations for the surface Temperature of small components, such as are

used in "i" circuits, are given in IEC 60079-11.

21 Requirements for all electrical apparatus

22.1 Electrical apparatus for use in potentially explosive atmospheres shall comply with

the requirements of this standard as modified by the specific standards for the types

of protection as listed in clause 1.

NOTE - If the electrical apparatus has to withstand particularly adverse service conditions

(for example rough handling, humidity effects, ambient temperature variations,

effects of chemical agents, corrosion), these should be specified to the

manufacturer by the user and are not the responsibility of the testing station.

22.2 Enclosures which can be opened more quickly than the time necessary

a) to allow incorporated capacitors, charged by a voltage of 200 V or more, to

discharge to a value of residual energy of

- 0,2 mJ for electrical apparatus of Group I or Group IIA, or

- 0,06 mJ for electrical apparatus of Group IIB, or

- 0,02 mJ for electrical apparatus of Group IIC, including apparatus marked

Group II only,

- or double the above energy levels if the charging voltage is less than 200 V,

b) or to allow the cooling of enclosed hot components to a surface temperature

below the temperature class of the electrical apparatus

shall either be marked with the warning AFTER DE-ENERGISING, DELAY Y

MINUTES BEFORE OPENING,

Y being the value in. minutes of the delay required;

or alternatively, the apparatus may be marked with the warning DO NOT OPEN

WHEN AN EXPLOSIVE GAS ATMOSPHERE MAY BE PRESENT.


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22 Non-metallic enclosures and non-metallic parts of enclosures

23.1 General

The following requirements, and those of 23.4.7, apply to non-metallic enclosures

and non-metallic parts of enclosures, on which the type of protection depends.

However, for sealing rings (see 3.19) on which the 'type of protection depends, the

proof furnished according to B.3.3 is sufficient.

23.1.1 The documents according to 23.2 shall specify both the material and the

manufacturing process of the enclosure or part of the enclosure.

23.1.2 The specification for plastic materials shall includea) the name of the manufacturer:

b) the exact and complete reference of the material, including its colour, percentage of

fillers and any other additives, if used:

c) the possible surface treatments. such as varnishes, etc.;

d) the temperature index TI corresponding to the 20 000 h point on the thermal

endurance graph without loss of flexural strength exceeding 50 %. determined in

accordance with IEC 60216-1 and IEC 60216-2 and based on he flexing property in

accordance with ISO 178. If the material does not break in this test before exposure

to the heat. the index shall be based on the tensile strength in accordance with ISO

527-2 with test bars of type 1A or 1B.

The data by which these characteristics are defined shall be supplied by the

manufacturer.

23.1.3 The testing station is not required to verily compliance of the material with its

definition.

23.2 Thermal endurance

The plastic materials shall have a temperature index TI corresponding to the 20 000

h point (see 7.1.2) of at least 20 K greater than the temperature of the hottest point

of the enclosure or the part of the enclosure (see 23.4.6.1), having regard to the

maximum ambient temperature in service (see 5.2).


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The endurance to heat and to cold of the enclosures, or parts of enclosures, of

plastic materials shall be satisfactory (see 23.4.7.3 and 23.4.7.4).

23.3 Electrostatic charges on enclosures or parts of enclosures of plastic material

The following requirements apply only to plastic enclosures, to plastic parts of

enclosures and to other exposed plastic parts of electrical apparatus for

- non-fixed electrical apparatus;

- fixed apparatus with plastic parts that are likely to be rubbed or cleaned on site.

23.3.1 Electrical apparatus of Group I

Enclosures of plastic material with surface area projected in any direction of more

than 100 cm2 shall be so designed that under normal conditions of use,

maintenance and cleaning, danger of ignition due to electrostatic charges is

avoided.

This requirement shall be satisfied by suitable selection of the material so that the

insulation resistance, measured according to the method given in 23.4.7.8 does not

exceed 1 GO at (23 2) C and (50 5) % relative humidity, or by virtue of the size,

shape and, layout, or other protective methods, such that dangerous electrostatic

charges are not likely to occur.

If, however, the danger of ignition cannot be avoided in the design, a warning label

shall indicate the safety measures to be applied in service.

NOTE 1 - When selecting electrical insulating materials, attention should be paid to

maintaining a minimum insulation resistance to avoid problems arising from

touching exposed plastic parts that are in contact with live parts.

NOTE 2 - Further restrictions may apply to plastic enclosures for use in areas where an

explosive gas atmosphere is present continuously or is present for longperiods.

23.3.2 Electrical apparatus of Group II


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Enclosures shall be so designed that under normal conditions of use, maintenance

and cleaning, danger of ignition due to electrostatic charges is avoided. This

requirement shall be satisfied by either of the following:

a) by suitable selection of the material so that the insulation resistance of the

enclosure, measured in accordance to 23.4.7.8. does not exceed 1 Gat (23

2) C and (50 5) % relative humidity;

b) or by limitation of the surface area of plastic enclosures or plastic parts of

enclosures as follows (see also note 2):

- for Group IlA and HIS apparatus to a maximum of 100 cm2, except that

this may be increased to a maximum of 400 cm2if the exposed areas of

plastics are surrounded by conductive earthed frames:

- for Group IIC apparatus, including light-transmitting parts, to a maximum

of 20 cm, except that this may be increased to a maximum of 100 cm if

the plastic parts are additionally protected against the occurrence of

dangerous electrostatic charges;

c) or by virtue of the size, shape and lay-out, or other protective methods, such

that dangerous electrostatic charges are not likely to occur.

If the danger of ignition cannot be avoided in the design of the apparatus, a

warning label shall indicate the safety measures to be applied in service.

NOTE 1 When selecting electrical insulating materials attention should be paid to

maintaining a minimum insulation resistance to avoid problems arising from

touching exposed plastic parts that are in contact with live parts.

NOTE 2 Further restrictions may apply to plastic enclosures for use in areas where an

explosive gas atmosphere is present continuously or is present for long periods (zone 0).

23.4 Threaded holes

Threaded holes for fasteners which secure covers intended to be opened in service

for adjustment, inspection and other operational reasons may only be tapped into

the plastic material when the thread form is compatible with the plastic material of

the enclosure.


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23 Enclosures containing light metals

24.1 Materials used in the construction of enclosures of electrical apparatus of Group I

shall not contain, by mass.

a) more than 15% in total of aluminium, magnesium and titanium; and

b) more than 6% in total of magnesium and titanium.

NOTE values for Group II are under consideration

24.2 Threaded holes in enclosures for fasteners which secure covers intended to be

opened in service for adjustment, inspection and other operational reasons may

only be tapped in the material of the enclosure when the thread form is compatible

with the material used for the enclosure.

24.3 The provisions of 8.1 do not apply to Group I surveying instruments carried by

persons.

24 Fasteners

25.1 General

Parts necessary to achieve a standard type of protection or used to prevent access

to uninsulated live parts shall be capable of being released or removed only with

the aid of a tool.

Fastening screws for enclosures of materials containing light metals may be made

of light metal or plastics if the material of the fastener is compatible with that of the

enclosure.

25.2 Special fasteners

When any of standards for a specific standard type of protection required a special

fastener, this shall conform to the following ;

- the thread shall be coarse pitch in accordance with ISO 262, with a tolerance fit

of 6g/6H in accordance with ISO 965;


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- the head of the screw or nut shall be in accordance with ISO 4014, ISO 4017,

ISO 4032 or ISO 4762, and, in the case of hexagon socket set screws, ISO

4026, ISO 4027, ISO 4028 or ISO 4029;

- the holes of the electrical apparatus shall comply with the requirements of 9.3.

NOTE - For Group I the heads of special fasteners liable to mechanical damage in

normal service which may invalidate the type of protection should be protected,

for example by the use of shrouds or counter-bored holes.

25.3 Electrical apparatus - holes for special fasteners

25.3.1 Holes for the threaded fasteners of 9.2 shall be threaded for a distance to accept a;

thread engagement, h, at least equal to the major diameter of the thread of the

fastener (see figures 1 and 2).

25.3.2 The thread shall have a tolerance fit of 6H in accordance with ISO 965, and either:

a) the hole under the head of the associated fastener shall allow a clearance not

greater than a medium tolerance fit of H13 in accordance with ISO 286-2 (see

figure 1 and ISO 273); or

b) the hole under the head (or nut) of an associated reduced shank fastener shall be

threaded to enable the fastener to be retained. The dimensions of the threaded

hole shall be such that the surrounding surface in contact with the head of such a

fastener shall be at least equal to that of a fastener without a reduced shank in a

clearance hole (see figure 2).

h major diameter of the a thread of the fastener

cmaximum clearance permitted by tolerance of fit H13 of ISO 286-2.

Figure 1 - Tolerances and clearance for threaded fasteners


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standard clearance hole appropriate to the threadfrom

h major diameter of the thread of the fastener

X the contact dimension of a reduced shank fastener

X the contact dimension of a standard head of a standard fastener (without

reduced shank) threaded throughout its length with the size of thread used

Figure 2 - Contact surface under head of fastener wi th a reduced shank

25.3.3 In the case of hexagon socket set screws, the screw shall have a tolerance fit of 6H

in accordance with ISO 965 and shall not protrude from the threaded hole after

tightening.

25 Interlocking devices

Interlocking devices used to maintain a type of protection shall be so constructed that

their effectiveness cannot readily be defeated by the use, for example, of a

screwdriver or pliers.


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26 Bushings

Bushings used as connection facilities and which may be subjected to a torque

while the connection or disconnection is being made shall be mounted in such a

way that all parts are secured against turning

27 Connection facilities for earthing or bonding conductors

28.1 A connection facility for the connection of an earthing or equipotential bonding

conductor shall be provided inside the terminal compartment of electrical apparatus

and near the other connection facilities.

28.2 Electrical apparatus with a metallic enclosure shall have an additional external

connection facility for an earthing or equipotential bonding conductor. This external

connection facility shall be electrically in contact with the facility required in 15.1.

The external connection facility is not required for electrical apparatus which is

designed to be moved when energised and is supplied by a cable incorporating an

earthing or equipotential bonding conductor.

NOTE - The expression 'electrically in contact' does not necessarily involve the use of a

conductor.

28.3 Neither an internal nor external earthing or bonding connection facility is required

for electrical apparatus for which earthing (or bonding) is not required, such as

electrical apparatus having double or reinforced insulation. or for which

supplementary earthing is not necessary.

28.4 Earthing or equipotential bonding connection facilities shall allow for the effective

connection of at least one conductor with a cross-sectional area as, in table 3.


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Table 3 - Minimum cross-sectional areas of protective conductors

Cross-sectional area of phase

conductors o f the installation S

Minimum cross-sectional area of the

corresponding protective conductor Sp

mm mm

S 16 S

16 < S 35 16

S 35 0.5 S

In addition, earthing or bonding connection facilities on the outside of electrical

apparatus shall provide for effective connection of a conductor of at least 4 mm2.

28.5 Connection facilities shall be effectively protected against corrosion. They shall also

be designed so that the conductors are secured against loosening and twisting and

so that the contact pressure is maintained.

Contact pressure of electrical connections shall not be affected by dimensional

changes of insulating materials in service, due to temperature or humidity, etc.

Special precautions shall be taken if one of the parts in contact consists of a

material containing light metal. One example of a means of connecting to a material

containing light metal is to use an intermediate part made from steel.

28 Cable and condui t entries

29.1 The manufacturer shall specify in the documents submitted according to 23.2, the

entries intended for use with cable or conduit, their position on the apparatus and

the maximum number permitted.

29.2 Cable and conduit entries shall be constructed and fixed so that they do not after

the specific characteristics of the type of protection of the electrical apparatus on

which they are mounted. This shall apply to the whole range of cable dimensions

specified by the manufacturer of the cable entries as suitable for use with those

entries.


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29.3 Cable and conduit entries may form an integral part of the apparatus, i.e. one major

element or part forms an inseparable part of the enclosure of the apparatus. In such

cases the entries shall be tested and certified with the apparatus.

NOTE - Cable and conduit entries, which are separate from, but installed with the

apparatus, are usually tested and certified separately from the apparatus but may

be tested and certified together with the apparatus if the apparatus manufacturer

so requests.

29.4 Cable entries, whether integral or separate, shall meet the relevant requirements of

annex B.

29.5 Where the design of a Group I cable entry is such that twisting of the cable can be

transmitted to the connections, then an anti-rotation device shall be fitted.

29.6 Entry by conduit shall be either by screwing into threaded holes or by locking in

plain holes:

- in the wall of the enclosure; or

- in an adaptor plate designed to be fitted in or on the walls of the enclosure; or

- into a suitable stopping box, integral with, or attached to the wall of the

enclosure.

29.7 Blanking elements, intended to close openings in the enclosure walls of electrical

apparatus, when they are not fitted with cable or conduit entries, shall, together with

the enclosure wall of the apparatus, satisfy the requirements of the specific type of

protection concerned. The means provided for this shall be such that the blanking

element can be removed only with the aid of a tool.

29.8 When the temperature under rated conditions is higher than 70 C at the cable or

conduit entry point, or 80 C at the branching point of the conductors, the outside of

the electrical apparatus shall be marked as a guide for the selection by the user ofthe cable or of the wiring in the conduit (see figure 3).


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1. Entry point

2. Branching point

3. Sealing

4. Filling compound

Figure 3a cable entry Figure 3b Condui t entry

Figure 3 Illust ration of entry points and branching points


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29 Flameproof enclosure d

30.1 Definitions

For the purpose of this standard. the following definitions, in addition to those given

in IEC 60079-0, apply.

30.1.1 Flameproof enclosure "d"

an enclosure in which the parts which can ignite an explosive atmosphere are

placed and which can withstand the pressure developed during an internal

explosion of an explosive mixture, and which prevents the transmission of the

explosion to the explosive atmosphere surrounding the enclosure

30.1.2 Volumetotal internal volume of the enclosure. However. for enclosures in which the

contents are essential in service. the volume to be considered is the remaining free

volume

NOTE - For luminaires, the volume is determined without lamps fitted.

30.1.3 Flameproof joint

place where the corresponding surfaces-of two parts of an enclosure come

together, or the conjunction of enclosures. and which prevents the transmission of

an internal explosion to tote explosive atmosphere surrounding the enclosure

30.1.4 Width of flameproof joint (L)

shortest path through a flameproof joint from the inside to the outside of an

enclosure

30.1.5 Distance (I)

shortest path through a flameproof joint, when the width of the joint L is interruptedby holes intended for the passage of fasteners for assembling the parts of the

flameproof enclosure


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30.1.6 Gap of flameproof joint (i)

distance between the corresponding surfaces of a flameproof joint when the

electrical apparatus enclosure has been assembled. For cylindrical surfaces,

forming cylindrical joints. the gap is the difference between the diameters of the

bore and the cylindrical component

30.1.7 Maximum

maximum gap of a joint of 25 mm in width which prevents any transmission of an

explosion in ` 10 tests made under the conditions specified in IEC 60079-1A

30.1.8 Shaft

Part of circular cross-section used for the transmission of rotary movement `

30.1.9 Operating rod

Part used for the transmission of control movements which may be rotary or linear

or a ' combination of the two

30.1.10 Pressure-piling

Results of an ignition a compartment or subdivision enclosure, of gas mixture pre-

compressed. for example, due to a primary ignition in another compartment or

subdivision

30.1.11 Quick-acting door or cover

Door or cover provided with a device which permits opening or closing by simple

opening or o simple operation, such as the movement of a lever or the rotation of

a wheel. The device is arranged so that the operation has two stages :

- one for locking or unlocking:

- another for opening or closing

30.1.12 Door or cover fixed by threaded fastenersDoor cover. the opening or closing of which . requires the manipulation of one or

more threaded fasteners (screws. studs. bolts or nuts)

30.1.13 Threaded door or cover

Door or cover which is assembled to a flameproof enclosure by a threaded

flameproof joint


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30.1.14 Breathing device

Integral or separable pas of a flameproof enclosure designed to permit exchange

between the atmosphere inside the enclosure and the surrounding atmosphere

30.1.15 Draining device

Integral or Separable part of a flameproof enclosure designed to permit water

formed by condensation to escape from the enclosure

30.2 Apparatus grouping and temperature classification

The apparatus grouping and temperature classification defined in IEC 60079-0 for

the use of electrical apparatus in potentially explosive atmospheres apply to

flameproof enclosures. The subdivisions A. B. C lot electrical apparatus of Group 0

also apply.

30.3 Flameproof joints

30.3.1 General requirements

All flameproof joints, whether permanently closed or designed to. be opened from

time to time, shall comply, in the absence of pressure, with the appropriate

requirements of clause 5.

The design of joints shall be appropriate to the mechanical constraints applied to

them.

NOTE - The values given in clause 5 constitute the necessary conditions. Additional

measures may be necessary in order to pass the non-transmission test of 15.2.

The surface of joints may be protected against corrosion.

Coating with paint or powder-coat finish is not permitted. Other coating material

may be used if the material and application procedure have been shown not toadversely affect the flameproof properties of the joint.

30:3:2 Non-threaded joints

30.3.2.1 Width of joints (L)


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The width of joints shall not be less than the minimum values given in tables 1

and 2. The width of joints for cylindrical metallic parts press-fitted into the walls of

a metallic flameproof enclosure of a volume not greater than 2 000 cm3 may be

reduced to 5 mm. if

- the design does not rely only on an interference fit to prevent the part being

displaced during the type tests of clause 15, and

- the assembly meets the impact test requirements of IEC 60079-0. taking the

worst-case interference fit tolerances into account. and

- the external diameter of the press-fitted part, where the width of the joint is

measured, does not exceed 60 mm.

30.3.2.2 Gap (i)

The gap, if one exists. between the surfaces of a joint shall nowhere exceed the

maximum values given in tables 1 and 2.

The surfaces of joints shall be such that their average roughness Ra (derived

from ISO 468:1982. Surface roughness - Parameters, their values and general

rules for specifying requirements - withdrawn 1998) does not exceed 6.3 m.

For flanged joints there shall be no intentional gap between the surfaces. except

for quick-acting doors or covers.

For electrical apparatus of Group l, it shall be possible to check. directly or

indirectly, the gaps of hanged joints of covers and doors designed to be opened

from time to time. Figure 1 shows an example of construction for indirect checking

of a flameproof joint.


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Table 1 Minimum wid th of joint and maximum gap for enclosure of Groups I, IIA

and IIB

Maximum gap mm

for volume (cm3) for volume (cm3) for volume (cm3) for volume (cm3)

V 100 100 < V 500 500 < V 2000 V > 2000Type of joint

Minimum widthof jointL mm I IIA IIB I IIA IIB I IIA IIB I IIA IIB

6 0.30

0.30

0.20

- - - - - - - - -

9.5 0.35

0.30

0.20

0.35

0.30

0.20

- - - - - -

12.5 0.40

0.30

0.20

0.40

0.30

0.20

0.40

0.30

0.20

0.40

0.20

0.15

Flanged cylindricalof spigot joints

25 0.50

0.40

0.20

0.50

0.40

0.20

0.50

0.40

0.20

0.50

0.40

0.20

6 0.30

0.30

0.20

- - - - - - - - -

9.5 0.35 0.35 0.20 0.35 0.30 0.20 - - - - - -

12.5 0.40

0.35

0.25

0.40

0.30

0.20

0.40

0.30

0.20

0.40

0.20

-

25 0.50

0.40

0.30

0.50

0.40

0.25

0.50

0.40

0.25

0.50

0.40

0.20

Steevebearings

40 0.60

0.50

0.40

0.60

0.50

0.30

0.60

0.50

0.30

0.60

0.50

0.25

6 0.45

0.45

0.30

- - - - - - - - -

9.5 0.50

0.45

0.35

0.50

0.40

0.25

- - - - - -

12.5 0.60

0.50

0.40

0.60

0.45

0.30

0.60

0.45

0.30

0.60

0.30

0.20

25 0.75

0.60

0.45

0.75

0.60

0.40

0.75

0.60

0.40

0.75

0.60

0.30

Cylindri-cal

joints forshaftglanosofrotatingelectricalmachines with Rolling-

elementbearings

40 0.80

0.75

0.60

0.80

0.75

0.45

0.80

0.75

0.45

0.80

0.75

0.40

NOTE : constructional values rounded according to ISO 31-0 should be taken when determining themaximum gap


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Table 2 Minimum w idth o f join t and maximum gap for group IIC enclosure

Maximum gap mm

forvolumecm3

forvolumecm3

forvolumecm3

forvolumecm3

Type of jointMinimumwidth of

joint L mm V 100 100 < V500

500 < V2000

V > 2000

Flanged joints 1) 6 L < 9.5 0.10 - - -9.5L


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30.3.2.3 Threaded joints

Threaded joints shall comply with the requirements in tables 3 or 4.

Table 3 Cylindrical threaded jo ints

Pitch 0.7 mm2Thread form andquality of fit

Medium or fine tolerance quality according to ISO965-1 and ISO 965-3b

Threads engaged 5Depth of engagementVolume < 100 ccm3 5Volume < 100 ccm3 8 mm

a Where the pitch exceeds 2 mm, special manufacturing precautions maybe necessary (for example, more threads engaged) to ensure that theelectrical apparatus can pass the test for non-transmission of an internalignition which is prescribed in 15.2

b Cylindrical threaded joints which do not conform with the ISO 965-3, in

respect of thread form or quality of fit, are permitted if the test for non-transmission of an internal ignition that is prescribed in 15.2 is passedwhen the width of the threaded joint specified by the manufacturer isreduce by the amount specified in table 6

Table 4 Taper threaded jo ints

Pitch 0.9 mmThreads provided oneach part

6

Threads engaged 5

The internal and external thread should have the same cone angle andthread form which shall be definedNOTE Difficulties may be encountered in achieving the five threadengagement for tapered threads when using standard gauging practive

30.3.2.4 Gaskets (including O-rings)

If a gasket of compressible or elastic material is used, for example, to protect

against the ingress of moisture or dust or against leakage of a liquid, it shall be

applied as a supplement. that is to say neither be taken into account in the

determination of the width of the flameproof joint nor interrupt it.

The gasket shall then be mounted so that


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- the permissible gap and width of flanged joints or the plane part of a spigot joint

are maintained.

- the minimum width of joint of a cylindrical joint or the cylindrical part of a Spigot

join' are maintainer before and after compression.

These requirements do not apply to cable entries (see 13.1) or to joints, which

contain a sealing gasket of metal or of a non-flammable compressible material

with a metallic sheath. Such a sealing gasket contributes to the explosion

protection, and in this case the gap between each surface of the plane part shall

be measured after compression. The minimum width of the cylindrical part shall

be maintained before and after compression.

30.3.2.5 Apparatus using capillaries

The capillaries shall either comply with the gap dimensions given in table 1 or

table 2 for cylindrical joints using 0 as the diameter of the inner part, or when the

capillaries do not conform to the gaps given in these tables, the apparatus shall

be certified if they pass the test for non-transmission of an internal ignition given

in 15.2.

30.4 Cable entries

Cable entries, whether integral or separate. shall meet the requirements of this

standard. the relevant requirements of annex C and create. on the enclosure. the

joint widths and gaps prescribed in clause 5.

Where cable entries are integral with the enclosure or specific to the enclosure they

be tested as part of the enclosure concerned.

Where cable entries are separate

- threaded Ex cable entries can be certified as apparatus. Such cable entries do

not have to be submitted to the tests of 15.1 and the routine test of clause 16.Threaded cable entries and their associated holes with threads not complying

with ISO standards shall be marked in such a manner that any confusion can be

precluded;

- other cable entries can only be certified as an Ex component.


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30.4.1 Conduit entries

30.4.1.1 Conduct entries are permitted only for electrical apparatus of Group II.

30.4.1.2 Conduit entries shall create on the enclosure the joint widths and gaps prescribed

in clause 5.

30.4.1.3 In addition, a sealing device such as a stopping box with setting compound shall

be provided, either in the flameproof enclosure or immediately at the entrance

thereto. A sealing device is considered as flitted immediately at the entrance of

the flameproof enclosure when the device is fixed to the enclosure either directly

or through an accessory necessary for coupling (such as a nipple or a three-piece

union); it shall satisfy the type test for sealing prescribed in 15.3. The, setting

compound shall be specified in the certificate either of the stopping box or of the

complete electrical apparatus having the flameproof enclosure. The part of the

stopping box between the setting compound and the flameproof enclosure shall

be treated as a flameproof enclosure, i.e. the joints shall comply with clause 5

and the assembly shall be submitted to the tests for non-transmission of 15.2.

NOTE - The seating device may be applied by the installer or user of the electrical

apparatus according to it ;ructions provided by the manufacturer

30.4.2 Plugs and sockets and cable couplers

Plugs and sockets shall be constructed and mounted so that they do not alter the

flameproof properties of the enclosure on which they are mounted, even when the

two parts of the plugs and sockets are separated.

30.4.2.1 The widths and the gaps of the flameproof joints (see clause 5) of the flameproof

enclosures of plugs and sockets and cable couplers shall be determined by the

volume which, exists at the moment of separation of the contacts other than those

for earthing or bonding or which are parts of circuits complying with IEC 60079-11.

30.4.2.2 For plugs and sockets and cable couplers, the flameproof properties of the

enclosure shall be maintained in the event of an internal explosion both when the

plugs and sockets or cat e couplers are connected together and 'at the moment of


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separation of the contacts other than those for earthing or bonding or those which

are parts of circuits complying with IEC 60079-11

30.4.2.3 The requirements of 13.3.2 and 13.3.3 do not apply to plugs and sockets nor to

cable couplers fixed together by means of

ee117-ex-proof installation-th-inst.pdf

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