EN 60079-0:2006

Electrical apparatus for explosive gas atmospheres - Part 0: General requirements

Superseded by EN 60079-0:2009

Elektrische Betriebsmittel für gasexplosionsgefährdete Bereiche - Teil 0: Allgemeine Anforderungen

Matériel électrique pour atmosphères explosives gazeuses - Partie 0: Règles générales

Električne naprave za eksplozivne plinske atmosfere - 0. del: Splošne zahteve (IEC 60079-0:2004, spremenjen)

General Information

• Status: Withdrawn
• Publication Date: 26-Jul-2006
• Withdrawal Date: 30-Sep-2008
• ICS: 29.260.20 - Electrical apparatus for explosive atmospheres
• Technical Committee: CLC/TC 31 - Electrical apparatus for explosive atmospheres - General requirements
• Drafting Committee: IEC/TC 31 - Electrical apparatus for potentially explosive atmospheres
• Parallel Committee: IEC/TC 31 - Electrical apparatus for potentially explosive atmospheres
• Current Stage: 9960 - Withdrawal effective - Withdrawal
• Start Date: 01-Jun-2012
• Completion Date: 01-Jun-2012
• Directive: 94/9/EC - Directive 94/9/EC of the European Parliament and the Council of 23 March 1994 on the approximation of the laws of the Member States concerning equipment and protective systems intended for use in potentially explosive atmospheres
• Ref Project: SIST EN 60079-0:2006 - Electrical apparatus for explosive gas atmospheres -- Part 0: General requirements

Relations

• Replaces: EN 60079-0:2004 - Electrical apparatus for explosive gas atmospheres - Part 0: General requirements
• Effective Date: 29-Jan-2023
• Replaced By: EN 60079-0:2009 - Explosive atmospheres - Part 0: Equipment - General requirements
• Effective Date: 28-Jan-2023

Standards Content (Sample)

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EUROPEAN STANDARD
EN 60079-0
NORME EUROPÉENNE
July 2006
EUROPÄISCHE NORM
ICS 29.260.20 Supersedes EN 60079-0:2004

English version
Electrical apparatus for explosive gas atmospheres
Part 0: General requirements
(IEC 60079-0:2004, modified)
Matériel électrique pour atmosphères Elektrische Betriebsmittel für
explosives gazeuses gasexplosionsgefährdete Bereiche
Partie 0: Règles générales Teil 0: Allgemeine Anforderungen
(CEI 60079-0:2004, modifiée) (IEC 60079-0:2004, modifiziert)

This European Standard was approved by CENELEC on 2005-09-13. CENELEC members are bound to
comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the Central Secretariat or to any CENELEC member.

This European Standard exists in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CENELEC member into its own language and
notified to the Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Cyprus, the Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia,
Spain, Sweden, Switzerland and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Central Secretariat: rue de Stassart 35, B - 1050 Brussels

© 2006 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 60079-0:2006 E
Foreword
The text of document 31/474A/FDIS, future edition 4 of IEC 60079-0, prepared by IEC TC 31, Electrical
apparatus for explosive atmospheres, was submitted to the IEC-CENELEC parallel vote and was
approved by CENELEC as EN 60079-0 on 2004-03-01.

A draft amendment to the European Standard EN 60079-0:2004, prepared by the Technical Committee
CENELEC TC 31, Electrical apparatus for explosive atmospheres - General requirements, was submitted
to the formal vote and was approved by CENELEC on 2005-09-13 to be combined with the published
standard and published as new edition of EN 60079-0.

This European Standard supersedes EN 60079-0:2004.

The following dates were fixed:

– latest date by which the amendment has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2007-02-01

– latest date by which the national standards conflicting
with the amendment have to be withdrawn (dow) 2008-10-01

This European Standard has been prepared under a mandate given to CENELEC by the European
Commission and the European Free Trade Association and covers essential requirements of
EC Directive 94/9/EC. See Annex ZZ.

Clauses, subclauses, notes, tables and figures which are additional to those in IEC 60079-0 are prefixed
“Z”.
Annexes ZA, ZB and ZZ have been added by CENELEC.

___________
- 3 - EN 60079-0:2006
Endorsement notice
The text of the International Standard IEC 60079-0:2004 was approved by CENELEC as a European
Standard with agreed common modifications as given below.

COMMON MODIFICATIONS
1 Scope
Add:
This European Standard EN 60079-0 covers Category M2, 2G and 3G apparatus and partly also
Category M1 and 1G.
In all cases where apparatus are involved the references to zones shall be read:

Zone 1 Category 2G
Zone 2 Category 3G
3 Terms and definitions
Add:
3.Z1
category
within an apparatus group, a category is the classification according to the required level of protection

NOTE 1 The term "apparatus" used throughout this standard, has the same meaning as the term "equipment" used
in EC Directive 94/9/EC.
NOTE 2 The categories are defined as given in Annex ZA.

6 Requirement for all electrical apparatus

Add:
6.Z1 Operating faults
6.Z1.1 Equipment, which is intended to be used in Zone 1, must be so designed and constructed as
to prevent ignition sources arising, even in the event of frequently occurring disturbances or equipment
operating faults, which normally have to be taken into account.

6.Z1.2 Equipment, which is intended to be used in Zone 2, must be so designed and constructed as
to prevent foreseeable ignition sources which can occur during normal operation.

6.Z2 Overloading of equipment
Dangerous overloading of equipment must be prevented at the design stage by means of integrated
measurement, regulation and control devices, such as over-current cut-off switches, temperature limiters,
differential pressure switches, flow meters, time-lag relays, over speed monitors and/or similar types of
monitoring devices.
29 Marking
29.2 General
Add after a):
z1) address of the manufacturer;

Add after j):
z2) CE marking together with the number of the notified body, which performed the quality assessment;
NOTE Z1 This marking to be included only for certain products as required by EC Directive 94/9/EC.
z3) year of construction;
z4) the specific marking of explosion protection followed by the symbol of the Equipment-group and

Category;
z5) for Equipment-group II, the letter "G" (concerning explosive atmospheres caused by gases, vapours
or mists);
z6) for Equipment-group I, the letter "M" for mining.

30 Instructions
Add:
30.Z1 Languages
The instructions must be drawn up in one of the Community languages by the manufacturer or his
authorized representative in the Community.

On being put into service, all equipment must be accompanied by a translation of the instruction in the
language or languages of the country in which the equipment or protective system is to be used and by
the instructions in the original language.

This translation must be made by either the manufacturer or his authorized representative established in
the Community or the person introducing the equipment into the language area in question.

By way of derogation from this requirement, the maintenance instructions for use by the specialist
personnel employed by the manufacturer or authorized representative established in the Community may
be drawn up in a single Community language understood by that personnel.

30.Z2 Documents
The instructions must contain the drawings and diagrams necessary for the putting into service,
maintenance, inspection, checking of correct operation and, where appropriate, repair of the equipment,
together with all useful instructions, in particular with regard to safety.

30.Z3 Literature
Literature describing the equipment must not contradict the instructions with regard to safety aspects.

Bibliography
Add the following notes for the standards indicated:

IEC 60079-14 NOTE  Harmonized as EN 60079-14:2003 (not modified).

IEC 60079-17 NOTE  Harmonized as EN 60079-17:2003 (not modified).

- 5 - EN 60079-0:2006
Add:
Annex ZA
(informative)
Classification of Equipment-groups into Categories

ZA.1 Categories
ZA.1.1 Equipment-group I
ZA.1.1.1 Category M1
Equipment-group I Category M1 comprises equipment designed and, where necessary, equipped with
additional special means of protection to be capable of functioning in conformity with the operational
parameters established by the manufacturer and ensuring a very high level of protection.

Equipment in this category is intended for use in underground parts of mines as well as those parts of
surface installations of such mines endangered by firedamp and/or combustible dust.

Equipment in this category is required to remain functional, even in the event of rare incidents relating to
equipment, with an explosive atmosphere present, and is characterized by means of protection such that:

- either, in the event of failure of one means of protection, at least an independent second means
provides the requisite level of protection,
- or the requisite level of protection is assured in the event of two faults occurring independently of each
other.
ZA.1.1.2 Category M2
Category M2 comprises equipment designed to be capable of functioning in conformity with the
operational parameters established by the manufacturer and ensuring a high level of protection.

Equipment in this category is intended for use in underground parts of mines as well as those parts of
surface installations of such mines likely to be endangered by firedamp and/or combustible dust.

This equipment is intended to be de-energized in the event of an explosive atmosphere.

The means of protection relating to equipment in this category assure the requisite level of protection
during normal operation and also in the case of more severe operating conditions, in particular those
arising from rough handling and changing environmental conditions.

ZA.1.2 Equipment-group II
ZA.1.2.1 Category 1
Equipment-group II Category 1 comprises equipment designed to be capable of functioning in conformity
with the operational parameters established by the manufacturer and ensuring a very high level of
protection.
Equipment in this category is intended for use in areas in which explosive atmospheres caused by
mixtures of air and gases, vapours or mists or by air/dust mixtures are present continuously, for long
periods or frequently.
Equipment in this category must ensure the requisite level of protection, even in the event of rare
incidents relating to equipment, and is characterized by means of protection such that:

- either, in the event of failure of one means of protection, at least an independent second means
provides the requisite level of protection,
- or the requisite level of protection is assured in the event of two faults occurring independently of each
other.
ZA.1.2.2 Category 2
Category 2 comprises equipment designed to be capable of functioning in conformity with the operational
parameters established by the manufacturer and of ensuring a high level of protection.

Equipment in this category is intended for use in areas in which explosive atmospheres caused by gases,
vapours, mists or air/dust mixtures are likely to occur.

The means of protection relating to equipment in this category ensure the requisite level of protection,
even in the event of frequently occurring disturbances or equipment faults which normally have to be
taken into account.
ZA.1.2.3 Category 3
Category 3 comprises equipment designed to be capable of functioning in conformity with the operating
parameters established by the manufacturer and ensuring a normal level of protection.

Equipment in this category is intended for use in areas in which explosive atmospheres caused by gases,
vapours, mists, or air/dust mixtures are unlikely to occur or, if they do occur, are likely to do so only
infrequently and for a short period only.

Equipment in this category ensures the requisite level of protection during normal operation.

- 7 - EN 60079-0:2006
Annex ZB
(normative)
Normative references to international publications
with their corresponding European publications

The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.

NOTE  When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD
applies.
Publication Year Title EN/HD Year

1) 2)
IEC 60034-5 – Rotating electrical machines - Part 5: EN 60034-5 2001
Degrees of protection provided by the integral
design of rotating electrical machines (IP
code) - Classification
1) 2)
IEC 60079-1 – Electrical apparatus for explosive gas EN 60079-1 2004
atmospheres - + corr. April 2006
Part 1: Flameproof enclosures 'd'

1) 2)
IEC 60079-2 – Electrical apparatus for explosive gas EN 60079-2 2004
atmospheres - + corr. April 2006
Part 2: Pressurized enclosures "p"

1)
IEC 60079-4 – Electrical apparatus for explosive gas - -
atmospheres - Part 4: Method of test for
ignition temperature
1)
IEC 60079-5 – Electrical apparatus for explosive gas - -
atmospheres - Part 5: Powder filling 'q'

1)
IEC 60079-6 – Electrical apparatus for explosive gas - -
atmospheres - Part 6: Oil-immersion "o"

1) 2)
IEC 60079-7 – Electrical apparatus for explosive gas EN 60079-7 2003
atmospheres - Part 7: Increased safety "e"

1) 2)
IEC 60079-10 – Electrical apparatus for explosive gas EN 60079-10 2003
atmospheres - Part 10: Classification of
hazardous areas
1)
IEC 60079-11 – Electrical apparatus for explosive gas -
-
atmospheres - Part 11: Intrinsic safety "i"

1) 2)
IEC 60079-15 – Electrical apparatus for explosive gas EN 60079-15 2005
atmospheres - Part 15: Type of protection "n"

1) 2)
IEC 60079-18 – Electrical apparatus for explosive gas EN 60079-18 2004
atmospheres - Part 18: Construction, test + corr. April 2006
and marking of type of protection
encapsulation "m" electrical apparatus

1)
Undated reference.
2)
Valid edition at date of issue.

Publication Year Title EN/HD Year
1) 2)
IEC 60079-25 – Electrical apparatus for explosive gas EN 60079-25 2004
atmospheres - Part 25: Intrinsically safe + corr. April 2006
systems
1) 2)
IEC 60079-26 (mod) – Electrical apparatus for explosive gas EN 60079-26 2004
atmospheres - Part 26: Construction, test and
marking of Group II Category 1 G electrical
apparatus
1) 2)
IEC 60086-1 – Primary batteries - Part 1: General EN 60086-1 2001

1) 3)
IEC 60095-1 – Lead-acid starter batteries - Part 1: General – –
requirements and methods of test

1) 2)
IEC 60192 – Low pressure sodium vapour lamps - EN 60192 2001
Performance specifications
1) 2)
IEC 60216-1 – Electrical insulating materials - Properties of EN 60216-1 2001
thermal endurance - Part 1: Ageing
procedures and evaluation of test results

1) 2)
IEC 60216-2 – Electrical insulating materials - Thermal EN 60216-2 2005
endurance properties - Part 2: Determination
of thermal endurance properties of electrical
insulating materials - Choice of test criteria

1) 2)
IEC 60423 (mod) – Conduits for electrical purposes - Outside EN 60423 1994
diameters of conduits for electrical
installations and threads for conduits and
fittings
1) 2)
IEC 60529 – Degrees of protection provided by enclosures EN 60529 1991
(IP Code) + corr. May 1993
1) 2)
IEC 60622 – Secondary cells and batteries containing EN 60622 2003
alkaline or other non-acid electrolytes -
Sealed nickel-cadmium prismatic
rechargeable single cells
1) 2)
IEC 60623 – Secondary cells and batteries containing EN 60623 2001
alkaline or other non-acid electrolytes -
Vented nickel-cadmium prismatic
rechargeable single cells
1) 2)
IEC 60662 (mod) – High pressure sodium vapour lamps EN 60662 1993

1) 2)
IEC 60947-1 – Low-voltage switchgear and controlgear - EN 60947-1 2004
Part 1: General rules + corr. November 2004

1) 2)
IEC 61056-1 – General purpose lead-acid batteries (valve EN 61056-1 2003
regulated types) - Part 1: General
requirements, functional characteristics -
Methods of test
1) 4) 2)4)
IEC 61150 – Alkaline secondary cells and batteries - EN 61150 1993
Sealed nickel-cadmium rechargeable
monobloc batteries in button cell design

3)
See EN 50342-1:2006, Lead-acid starter batteries -- Part 1: General requirements and methods of test.
4)
Withdrawn.
- 9 - EN 60079-0:2006
Publication Year Title EN/HD Year
1) 5) 2)
IEC 61436 – Secondary cells and batteries containing EN 61436 1998
alkaline or other non-acid electrolytes -
Sealed nickel-metal hydride rechargeable
single cells
1) 2)
IEC 61951-1 – Secondary cells and batteries containing EN 61951-1 2003
alkaline or other non-acid electrolytes -
Portable sealed rechargeable single cells -
Part 1: Nickel-cadmium
1) 2)
IEC 62013-1 – Caplights for use in mines susceptible to EN 62013-1 2006
firedamp - Part 1: General requirements -
Construction and testing in relation to the risk
of explosion
1) 2)
IEC 62086-1 – Electrical apparatus for explosive gas EN 62086-1 2005
atmospheres - Electrical resistance trace
heating - Part 1: General and testing
requirements
1)
ISO 48 – Rubber, vulcanized or thermoplastic - - -
Determination of hardness (hardness
between 10 IRHD and 100 IRHD)
1) 2)
ISO 178 – Plastics - Determination of flexural properties EN ISO 178 2003

ISO 179 Series Plastics - Determination of Charpy impact EN ISO 179 Series
strength
1)
ISO 262 – ISO general-purpose metric screw threads - - -
Selected sizes for screws, bolts and nuts

1) 2)
ISO 273 – Fasteners - Clearance holes for bolts and EN 20273 1991
screws
1) 2)
ISO 286-2 – ISO system of limits and fits - Part 2: Tables EN 20286-2 1993
of standard tolerance grades and limit
deviations for holes and shafts

1) 2)
ISO 527-2 – Plastics - Determination of tensile properties - EN ISO 527-2 1996
Part 2: Test conditions for moulding and
extrusion plastics
1)
ISO 965-1 – ISO general-purpose metric screw threads - - -
Tolerances - Part 1: Principles and basic data

1)
ISO 965-3 – ISO general purpose metric screw threads - - -
Tolerances - Part 3: Deviations for
constructional threads
1)
ISO 1817 – Rubber, vulcanized - Determination of the - -
effect of liquids
1) 2)
ISO 4014 – Hexagon head bolts - Product grades A and EN ISO 4014 2000
B
1) 2)
ISO 4017 – Hexagon head screws - Product grades A EN ISO 4017 2000
and B
1) 2)
ISO 4026 – Hexagon socket set screws with flat point EN ISO 4026 2003

5)
EN 61436 is superseded by EN 61951-2:2003.

Publication Year Title EN/HD Year
1) 2)
ISO 4027 – Hexagon socket set screws with cone point EN ISO 4027 2003

1) 2)
ISO 4028 – Hexagon socket set screws with dog point EN ISO 4028 2003

1) 2)
ISO 4029 – Hexagon socket set screws with cup point EN ISO 4029 2003

1) 2)
ISO 4032 – Hexagon nuts, style 1 - Product grades A EN ISO 4032 2000
and B
1) 2)
ISO 4762 – Hexagon socket head cap screws - Product EN ISO 4762 2004
grade A
1) 2)
ISO 4892-1 – Plastics - Methods of exposure to laboratory EN ISO 4892-1 2000
light sources - Part 1: General guidance

1)
ANSI/UL 746B – Polymeric Materials - Long-Term Property - -
Evaluations
- 11 - EN 60079-0:2006
Annex ZZ
(informative)
Coverage of Essential Requirements of EC Directives

This European Standard has been prepared under a mandate given to CENELEC by the European
Commission and the European Free Trade Association and within its scope the standard covers only the
following essential requirements out of those given in Annex II of the EC Directive 94/9/EC.

– ER 1.0.2 to ER 1.0.6
– ER 1.1
– ER 1.2.2 (partly), ER 1.2.3, ER 1.2.5 to ER 1.2.9
– ER 1.3.1 to ER 1.3.4
– ER 1.4.1, ER 1.4.2
– ER 1.6.2, ER 1.6.4
– ER 2.0.2.1, ER 2.0.2.2
– ER 2.2.1, ER 2.2.1.1 to ER 2.2.1.3
– ER 2.3.1.1, ER 2.3.1.2
Compliance with this standard provides one means of conformity with the specified essential
requirements of the Directive concerned.

WARNING: Other requirements and other EC Directives may be applicable to the products falling within
the scope of this standard.
___________
INTERNATIONAL IEC
STANDARD 60079-0
Fourth edition
2004-01
Electrical apparatus for explosive
gas atmospheres –
Part 0:
General requirements
© IEC 2004 Copyright - all rights reserved
No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical,
including photocopying and microfilm, without permission in writing from the publisher.
International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland
Telephone: [phone] Telefax: [phone] E-mail: [e-mail] Web: www.iec.ch
PRICE CODE
Commission Electrotechnique Internationale XB
International Electrotechnical Commission
Международная Электротехническая Комиссия
For price, see current catalogue

60079-0  IEC:2004 – 3 –
CONTENTS
FOREWORD.11
INTRODUCTION.17
1 Scope.19
2 Normative references.21
3 Terms and definitions .27
4 Apparatus grouping and temperature classification.39
4.1 Apparatus grouping.39
4.2 Group II.39
5 Temperatures.39
5.1 Environmental influences.39
5.2 Service temperature.41
5.3 Maximum surface temperature.41
5.4 Surface temperature and ignition temperature .43
5.5 Small components.43
6 Requirements for all electrical apparatus.45
6.1 General.45
6.2 Mechanical strength of apparatus.45
6.3 Opening times.45
6.4 Circulating currents.47
6.5 Gasket retention.47
7 Non-metallic enclosures and non-metallic parts of enclosures .47
7.1 General.47
7.2 Thermal endurance.49
7.3 Electrostatic charges on external non-metallic materials of enclosures.49
7.4 Threaded holes.51
8 Enclosures containing light metals.53
8.1 Material composition.53
8.2 Threaded holes.53
Fasteners .53
9.1 General.53
9.2 Special fasteners.55
9.3 Holes for special fasteners .55
10 Interlocking devices.59
11 Bushings.59
12 Materials used for cementing.59
13 Ex components.59
13.1 General.59
13.2 Mounting internal to apparatus .59
13.3 Mounting external to apparatus .61
14 Connection facilities and terminal compartments .61
14.1 General.61
14.2 Connection space.61
14.3 Type of protection.61
14.4 Creepage and clearance.61

60079-0  IEC:2004 – 5 –
15 Connection facilities for earthing or bonding conductors .61
15.1 Internal.61
15.2 External.61
15.3 Apparatus not requiring earthing .63
15.4 Size of conductor connection.63
15.5 Protection against corrosion.63
15.6 Secureness.63
16 Entries into enclosures .65
16.1 General.65
16.2 Identification of entries.65
16.3 Cable glands.65
16.4 Blanking elements.65
16.5 Conductor temperature.65
17 Supplementary requirements for rotating electrical machines .67
17.1 Fans and fan hoods.67
17.2 Ventilation openings for external fans.67
17.3 Construction and mounting of the ventilating systems .69
17.4 Clearances for the ventilating system .69
17.5 Materials for external fans and fan hoods .69
17.6 Equipotential bonding conductors.69
18 Supplementary requirements for switchgear .69
18.1 Flammable dielectric.69
18.2 Disconnectors.71
18.3 Group I – Provisions for locking.71
18.4 Doors and covers.71
19 Supplementary requirements for fuses .73
20 Supplementary requirements for plugs and sockets .73
20.1 Interlocking.73
20.2 Energized plugs.73
21 Supplementary requirements for luminaires .73
21.1 General.73
21.2 Covers.75
21.3 Special lamps.75
22 Supplementary requirements for caplights and handlights .75
22.1 Group I caplights and handlights .75
22.2 Group II caplights and handlights .75
23 Apparatus incorporating cells and batteries .77
23.1 Batteries.77
23.2 Cell types.77
23.3 Cells in a battery .79
23.4 Ratings of batteries .79
23.5 Mixture of cells.79
23.6 Interchangeability.79
23.7 Charging of primary batteries .79
23.8 Leakage.79

60079-0  IEC:2004 – 7 –
23.9 Connections.81
23.10 Orientation.81
23.11 Replacement of cells or batteries.81
24 Documentation.81
25 Compliance of prototype or sample with documents .81
26 Type tests.81
26.1 General.81
26.2 Test configuration.81
26.3 Tests in explosive test mixtures .81
26.4 Tests of enclosures.83
26.5 Thermal tests.91
26.6 Torque test for bushings .93
26.7 Non-metallic enclosures or non-metallic parts of enclosures .95
26.8 Thermal endurance to heat .95
26.9 Thermal endurance to cold .97
26.10 Resistance to light .97
26.11 Resistance to chemical agents for Group I electrical apparatus .99
26.12 Earth continuity.99
26.13 Surface resistance test of parts of enclosures of non-metallic materials.101
26.14 Charging tests.103
26.15 Measurement of capacitance .111
27 Routine verifications and tests.111
28 Manufacturer's responsibility.111
28.1 Certificate.111
28.2 Responsibility for marking.111
29 Marking.111
29.1 Location.113
29.2 General.113
29.3 Different types of protection.115
29.4 Order of marking.117
29.5 Ex components.117
29.6 Small apparatus and Ex components .117
29.7 Extremely small apparatus and Ex components .117
29.8 Warning markings.117
29.9 Cells and batteries.119
29.10 Examples of marking.119
30 Instructions.121
30.1 General.121
30.2 Cells and batteries.123

Annex A (normative) Ex cable glands.125
Annex B (normative) Requirements for Ex components.139
Annex C (informative) Example of rig for resistance to impact test.143

Bibliography.145

60079-0  IEC:2004 – 9 –
Figure 1 – Tolerances and clearance for threaded fasteners .57
Figure 2 – Contact surface under head of fastener with a reduced shank.57
Figure 3 – Illustration of entry points and branching points .67
Figure 4 – Assembly of test sample for earth-continuity test.101
Figure 5 – Test piece with painted electrodes .103
Figure 6 – Rubbing with a pure nylon cloth .107
Figure 7 – Discharging of a container with a probe connected to earth via a 0,1 μF
capacitor.109
Figure 8 – Charging by influence with a d.c. voltage power supply.109
Figure A.1 – Illustration of the terms used for cable glands .125
Figure A.2 – Rounded edge of the point of entry of the flexible cable .129
Figure C.1 – Example of rig for resistance to impact test .143

Table 1 – Ambient temperatures in service and additional marking .41
Table 2 – Classification of maximum surface temperatures for Group II electrical
apparatus .43
Table 3 – Assessment for T4 classification according to component size and ambient
temperature .43
Table 4 – Limitations of areas .51
Table 5 – Minimum cross-sectional area of protective conductors .63
Table 6 – Primary cells .77
Table 7 – Secondary cells.79
Table 8 – Tests for resistance to impact.87
Table 9 – Torque to be applied to the stem of bushing used for connection facilities.95
Table 10 − Text of warning markings .119
Table B.1 – Clauses with which Ex components shall comply .139

60079-0  IEC:2004 – 11 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
__________
ELECTRICAL APPARATUS FOR EXPLOSIVE
GAS ATMOSPHERES –
Part 0: General requirements
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
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International Standard IEC 60079-0 has been prepared by technical committee 31: Electrical
apparatus for explosive atmospheres.
This fourth edition cancels and replaces the third edition, published in 1998, and constitutes a
full technical revision.
The significant changes with respect to the previous edition are listed below:
• Standard atmospheric conditions re-introduced
• All requirements for third-party certification removed
• New type of protecti
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