Explosive atmospheres - Part 0: Equipment - General requirements

IEC 60079-0:2017 is also available as IEC 60079-0:2017 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.
IEC 60079-0:2017 specifies the general requirements for construction, testing and marking of Ex Equipment and Ex Components intended for use in explosive atmospheres. The standard atmospheric conditions (relating to the explosion characteristics of the atmosphere) under which it may be assumed that Ex Equipment can be operated are:
-temperature –20 °C to +60 °C;
-pressure 80 kPa (0,8 bar) to 110 kPa (1,1 bar); and
-air with normal oxygen content, typically 21 % v/v.
This part of IEC 60079 and other standards supplementing this standard specify additional test requirements for Ex Equipment operating outside the standard temperature range, but further additional consideration and additional testing may be required for Ex Equipment operating outside the standard atmospheric pressure range and standard oxygen content. Such additional testing may be particularly relevant with respect to Types of Protection that depend on quenching of a flame such as ‘flameproof enclosures “d”’ (IEC 60079-1) or limitation of energy, ‘intrinsic safety “i”’ (IEC 60079-11). This seventh edition cancels and replaces the sixth edition, published in 2011. This edition constitutes a technical revision. Refer to the Foreword of the document for a complete listing of the technical changes between edition 7.0 and the previous edition of the document.
Keywords: Ex Equipment and Ex Components intended for use in explosive atmospheres
The contents of the interpretation sheet 1 of April 2019, of the interpretation sheet 2 of June 2019 and the corrigendum 1 of January 2020 have been included in this copy.

Explosionsgefährdete Bereiche - Teil 0: Betriebsmittel - Allgemeine Anforderungen

Atmosphères explosives - Partie 0: Matériel - Exigences générales

IEC 60079-0:2017 est disponible sous forme de IEC 60079-0:2017 RLV qui contient la Norme internationale et sa version Redline, illustrant les modifications du contenu technique depuis l'édition précédente.
IEC 60079-0:2017 spécifie les exigences générales de construction, d'essais et de marquage de l’appareil Ex et des Composants Ex destinés à être utilisés dans des atmosphères explosives. Les conditions atmosphériques normales (relatives aux caractéristiques d’explosion de l’atmosphère) dans lesquelles, par hypothèse l’appareil Ex peut être utilisé, sont les suivantes:
-température de –20 °C à +60 °C;
-pression de 80 kPa (0,8 bar) à 110 kPa (1,1 bar); et
-air avec teneur normale en oxygène, typiquement 21 % v/v.
La présente partie de la norme IEC 60079 et les autres normes qui la complètent spécifient des exigences d’essai supplémentaires pour les appareils Ex fonctionnant hors de la plage normale de températures, une attention supplémentaire ultérieure et des essais complémentaires pouvant toutefois être exigés pour les appareils Ex fonctionnant hors de la plage normale de pressions atmosphériques et de la teneur normale en oxygène. De tels essais complémentaires peuvent se révéler pertinents, notamment pour les modes de protection qui dépendent de l’extinction d’une flamme, tels qu’une «enveloppe antidéflagrante «d»» (IEC 60079-1), ou de la limitation de l’énergie, tels que la «sécurité intrinsèque «i»» (IEC 60079-11). Reportez-vous à l'avant-propos du document pour une liste complète des modifications techniques entre l'édition 7.0 et édition précédente du document.
Mots-clés: l’appareil Ex et des Composants Ex destinés à être utilisés dans des atmosphères explosives.
Le contenu de la feuille d'interprétation 1 d'avril 2019, la feuille d'interprétation 2 de juin 2019 et le corrigendum 1 de janvier 2020 a été pris en considération dans cet exemplaire.

Eksplozivne atmosfere - 0. del: Oprema - Splošne zahteve

General Information

Status
Not Published
Public Enquiry End Date
29-Apr-2018
Current Stage
98 - Abandoned project (Adopted Project)
Start Date
20-Jul-2021
Due Date
25-Jul-2021
Completion Date
20-Jul-2021

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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Eksplozivne atmosfere - 0. del: Oprema - Splošne zahteveExplosionsgefährdete Bereiche - Teil 0: Betriebsmittel - Allgemeine AnforderungenAtmosphères explosives - Partie 0: Matériel - Exigences généralesExplosive atmospheres - Part 0: Equipment - General requirements29.260.20Electrical apparatus for explosive atmospheresICS:Ta slovenski standard je istoveten z:IEC 60079-0 Ed. 7.0oSIST IEC 60079-0:2018en,fr,de01-april-2018oSIST IEC 60079-0:2018SLOVENSKI

STANDARD
oSIST IEC 60079-0:2018

IEC 60079-0 Edition 7.0 2017-12 INTERNATIONAL STANDARD NORME INTERNATIONALE Explosive atmospheres –

Part 0: Equipment – General requirements
Atmosphères explosives –

Partie 0: Matériel – Exigences générales INTERNATIONAL ELECTROTECHNICAL COMMISSION COMMISSION ELECTROTECHNIQUE INTERNATIONALE

ICS 29.260.20
ISBN 978-2-8322-5065-5
® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale ®

Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé. oSIST IEC 60079-0:2018

– 2 – IEC 60079-0:2017  IEC 2017 CONTENTS FOREWORD ........................................................................................................................... 8 1 Scope ............................................................................................................................ 15 2 Normative references .................................................................................................... 16 3 Terms and definitions .................................................................................................... 18 4 Equipment grouping ....................................................................................................... 36 4.1 General ................................................................................................................. 36 4.2 Group I ................................................................................................................. 36 4.3 Group II ................................................................................................................ 36 4.4 Group III ............................................................................................................... 36 4.5 Equipment for a particular explosive gas atmosphere ............................................ 37 5 Temperatures ................................................................................................................ 37 5.1 Environmental influences ...................................................................................... 37 5.1.1 Ambient temperature ..................................................................................... 37 5.1.2 External source of heating or cooling ............................................................. 37 5.2 Service temperature .............................................................................................. 37 5.3 Maximum surface temperature .............................................................................. 38 5.3.1 Determination of maximum surface temperature ............................................ 38 5.3.2 Limitation of maximum surface temperature ................................................... 38 5.3.3 Small component temperature for Group I or Group II electrical equipment...................................................................................................... 39 5.3.4 Component temperature of smooth surfaces for Group I or Group II electrical equipment ....................................................................................... 40 6 Requirements for all equipment ..................................................................................... 41 6.1 General ................................................................................................................. 41 6.2 Mechanical strength of equipment ......................................................................... 41 6.3 Opening times ....................................................................................................... 41 6.4 Circulating currents in enclosures (e.g. of large electric machines) ....................... 42 6.5 Gasket retention ................................................................................................... 42 6.6 Electromagnetic and ultrasonic energy radiating equipment .................................. 42 6.6.1 General ......................................................................................................... 42 6.6.2 Radio frequency sources ............................................................................... 42 6.6.3 Ultrasonic sources ......................................................................................... 43 6.6.4 Lasers, luminaires, and other non-divergent continuous wave optical sources.......................................................................................................... 44 7 Non-metallic enclosures and non-metallic parts of enclosures ....................................... 44 7.1 General ................................................................................................................. 44 7.1.1 Applicability ................................................................................................... 44 7.1.2 Specification of materials ............................................................................... 44 7.2 Thermal endurance ............................................................................................... 45 7.2.1 Tests for thermal endurance .......................................................................... 45 7.2.2 Material selection .......................................................................................... 46 7.2.3 Alternative qualification of elastomeric sealing O-rings .................................. 46 7.3 Resistance to ultraviolet light ................................................................................ 46 7.4 Electrostatic charges on external non-metallic materials ....................................... 47 7.4.1 Applicability ................................................................................................... 47 7.4.2 Avoidance of a build-up of electrostatic charge for Group I or Group II .......... 47 oSIST IEC 60079-0:2018

IEC 60079-0:2017  IEC 2017 – 3 –

7.4.3 Avoidance of a build-up of electrostatic charge for Group III .......................... 49 7.5 Attached external conductive parts ....................................................................... 50 8 Metallic enclosures and metallic parts of enclosures ...................................................... 51 8.1 Material composition ............................................................................................. 51 8.2 Group I ................................................................................................................. 51 8.3 Group II ................................................................................................................ 51 8.4 Group III ............................................................................................................... 52 8.5 Copper Alloys ....................................................................................................... 52 9 Fasteners ...................................................................................................................... 52 9.1 General ................................................................................................................. 52 9.2 Special fasteners .................................................................................................. 53 9.3 Holes for special fasteners .................................................................................... 53 9.3.1 Thread engagement ....................................................................................... 53 9.3.2 Tolerance and clearance ............................................................................... 53 9.4 Hexagon socket set screws ................................................................................... 54 10 Interlocking devices ....................................................................................................... 54 11 Bushings ....................................................................................................................... 54 12 (Reserved for future use) ............................................................................................... 54 13 Ex Components ............................................................................................................. 54 13.1 General ................................................................................................................. 54 13.2 Mounting ............................................................................................................... 55 13.3 Internal mounting .................................................................................................. 55 13.4 External mounting ................................................................................................. 55 13.5 Ex Component certificate ...................................................................................... 55 14 Connection facilities ...................................................................................................... 55 14.1 General ................................................................................................................. 55 14.2 Type of protection ................................................................................................. 56 14.3 Creepage and clearance ....................................................................................... 56 15 Connection facilities for earthing or bonding conductors ................................................ 56 15.1 Equipment requiring earthing or bonding ............................................................... 56 15.1.1 Internal earthing ............................................................................................ 56 15.1.2 External bonding............................................................................................ 56 15.2 Equipment not requiring earthing .......................................................................... 56 15.3 Size of protective earthing conductor connection .................................................. 56 15.4 Size of equipotential bonding conductor connection .............................................. 57 15.5 Protection against corrosion .................................................................................. 57 15.6 Secureness of electrical connections .................................................................... 57 15.7 Internal earth continuity plate ................................................................................ 57 16 Entries into enclosures .................................................................................................. 57 16.1 General ................................................................................................................. 57 16.2 Identification of entries .......................................................................................... 57 16.3 Cable glands ......................................................................................................... 58 16.4 Blanking elements................................................................................................. 58 16.5 Thread adapters ................................................................................................... 58 16.6 Temperature at branching point and entry point .................................................... 59 16.7 Electrostatic charges of cable sheaths .................................................................. 59 17 Supplementary requirements for electric machines ........................................................ 60 17.1 General ................................................................................................................. 60 oSIST IEC 60079-0:2018

– 4 – IEC 60079-0:2017  IEC 2017 17.2 Ventilation............................................................................................................. 60 17.2.1 Ventilation openings ...................................................................................... 60 17.2.2 Materials for external fans ............................................................................. 60 17.2.3 Cooling fans of rotating electric machines ...................................................... 60 17.2.4 Auxiliary motor cooling fans ........................................................................... 61 17.2.5 Room ventilating fans .................................................................................... 61 17.3 Bearings ............................................................................................................... 62 18 Supplementary requirements for switchgear .................................................................. 62 18.1 Flammable dielectric ............................................................................................. 62 18.2 Disconnectors ....................................................................................................... 62 18.3 Group I – Provisions for locking ............................................................................ 63 18.4 Doors and covers .................................................................................................. 63 19 Reserved for future use ................................................................................................. 63 20 Supplementary requirements for external plugs, socket outlets and connectors for field wiring connection ................................................................................................... 63 20.1 General ................................................................................................................. 63 20.2 Explosive gas atmospheres .................................................................................. 64 20.3 Explosive dust atmospheres ................................................................................. 64 20.4 Energized plugs .................................................................................................... 64 21 Supplementary requirements for luminaires ................................................................... 64 21.1 General ................................................................................................................. 64 21.2 Covers for luminaires of EPL Mb, EPL Gb, or EPL Db ........................................... 64 21.3 Covers for luminaires of EPL Gc or EPL Dc .......................................................... 65 21.4 Sodium lamps ....................................................................................................... 65 22 Supplementary requirements for caplights and handlights ............................................. 65 22.1 Group I caplights .................................................................................................. 65 22.2 Group II and Group III caplights and handlights

................................................... 65 23 Equipment incorporating cells and batteries ................................................................... 66 23.1 General ................................................................................................................. 66 23.2 Interconnection of cells to form batteries ............................................................... 66 23.3 Cell types .............................................................................................................. 66 23.4 Cells in a battery ................................................................................................... 69 23.5 Ratings of batteries ............................................................................................... 69 23.6 Interchangeability ................................................................................................. 69 23.7 Charging of primary batteries ................................................................................ 69 23.8 Leakage ................................................................................................................ 69 23.9 Connections .......................................................................................................... 69 23.10 Orientation ............................................................................................................ 69 23.11 Replacement of cells or batteries .......................................................................... 69 23.12 Replaceable battery pack ...................................................................................... 70 24 Documentation .............................................................................................................. 70 25 Compliance of prototype or sample with documents ....................................................... 70 26 Type tests ..................................................................................................................... 70 26.1 General ................................................................................................................. 70 26.2 Test configuration ................................................................................................. 70 26.3 Tests in explosive test mixtures ............................................................................ 70 26.4 Tests of enclosures ............................................................................................... 71 26.4.1 Order of tests ................................................................................................ 71 oSIST IEC 60079-0:2018

IEC 60079-0:2017  IEC 2017 – 5 –

26.4.2 Resistance to impact ..................................................................................... 73 26.4.3 Drop test ....................................................................................................... 74 26.4.4 Acceptance criteria ........................................................................................ 75 26.4.5 Degree of protection (IP) by enclosures ......................................................... 75 26.5 Thermal tests ........................................................................................................ 76 26.5.1 Temperature measurement ............................................................................ 76 26.5.2 Thermal shock test ........................................................................................ 78 26.5.3 Small component ignition test (Group I and Group II) ..................................... 78 26.6 Torque test for bushings ....................................................................................... 79 26.6.1 Test procedure .............................................................................................. 79 26.6.2 Acceptance criteria ........................................................................................ 80 26.7 Non-metallic enclosures or non-metallic parts of enclosures ................................. 80 26.7.1 General ......................................................................................................... 80 26.7.2 Test temperatures ......................................................................................... 80 26.8 Thermal endurance to heat ................................................................................... 80 26.9 Thermal endurance to cold .................................................................................... 81 26.10 Resistance to UV light ........................................................................................... 81 26.10.1 General ......................................................................................................... 81 26.10.2 Light exposure ............................................................................................... 82 26.10.3 Acceptance criteria ........................................................................................ 82 26.11 Resistance to chemical agents for Group I equipment ........................................... 82 26.12 Earth continuity ..................................................................................................... 83 26.13 Surface resistance test of parts of enclosures of non-metallic materials ................ 84 26.14 Measurement of capacitance ................................................................................ 85 26.14.1 General ......................................................................................................... 85 26.14.2 Test procedure .............................................................................................. 85 26.15 Verification of ratings of ventilating fans ................................................................ 86 26.16 Alternative qualification of elastomeric sealing O-rings ......................................... 86 26.17 Transferred charge test ......................................................................................... 86 26.17.1 Test equipment .............................................................................................. 86 26.17.2 Test sample ................................................................................................... 87 26.17.3 Test procedure .............................................................................................. 87 27 Routine tests ................................................................................................................. 88 28 Manufacturer's responsibility ......................................................................................... 88 28.1 Conformity with the documentation ....................................................................... 88 28.2 Certificate ............................................................................................................. 89 28.3 Responsibility for marking ..................................................................................... 89 29 Marking ......................................................................................................................... 89 29.1 Applicability .......................................................................................................... 89 29.2 Location ................................................................................................................ 89 29.3 General ................................................................................................................. 89 29.4 Ex marking for explosive gas atmospheres ........................................................... 90 29.5 Ex marking for explosive dust atmospheres .......................................................... 92 29.6 Combined types (or levels) of protection ............................................................... 95 29.7 Multiple types of protection ................................................................................... 95 29.8 Ga equipment using two independent Gb types (or levels) of protection ................ 95 29.9 Boundary wall ....................................................................................................... 95 29.10 Ex Components .................................................................................................... 95 29.11 Small Ex Equipment and small Ex Components .................................................... 96 oSIST IEC 60079-0:2018

– 6 – IEC 60079-0:2017  IEC 2017 29.12 Extremely small Ex Equipment and extremely small Ex Components .................... 96 29.13 Warning markings ................................................................................................. 96 29.14 Cells and batteries ................................................................................................ 97 29.15 Electric machines operated with a converter ......................................................... 97 29.16 Examples of marking ............................................................................................. 98 30 Instructions .................................................................................................................. 101 30.1 General ............................................................................................................... 101 30.2 Cells and batteries .............................................................................................. 102 30.3 Electric machines ................................................................................................ 103 30.4 Ventilating fans ................................................................................................... 103 30.5 Cable glands ....................................................................................................... 104 Annex A (normative)

Supplementary requirements for cable glands ................................... 105 A.1 General ............................................................................................................... 105 A.2 Constructional requirements ............................................................................... 105 A.2.1 Cable sealing ............................................................................................... 105 A.2.2 Filling compounds ........................................................................................ 106 A.2.3 Clamping ..................................................................................................... 106 A.2.4 Lead-in of cable ........................................................................................... 106 A.2.5 Release by a tool ......................................................................................... 107 A.2.6 Fixing .......................................................................................................... 107 A.2.7 Degree of protection .................................................................................... 107 A.3 Type tests ........................................................................................................... 107 A.3.1 Tests of clamping of non-armoured and braided cables ............................... 107 A.3.2 Tests of clamping of armoured cables .......................................................... 110 A.3.3 Type test for resistance to impact ................................................................ 111 A.3.4 Test for degree of protection (IP) of cable glands ........................................ 112 A.4 Marking ............................................................................................................... 113 A.4.1 Marking of cable glands ............................................................................... 113 A.4.2 Identification of cable-sealing rings .............................................................. 113 A.5 Instructions ......................................................................................................... 113 Annex B (normative)

Requirements for Ex Components ..................................................... 115 Annex C (informative)

Example of rig for resistance to impact test ..................................... 118 Annex D (informative)

Electric machines connected to converters ...................................... 119 Annex E (informative)

Temperature evaluation of electric machines ................................... 120 Annex F (informative)

Guidance flowchart for tests of non-metallic enclosures or

non-metallic parts of enclosures (26.4) ...................................................................................... 123 Annex G (informative)

Guidance flowchart for tests of cable glands ................................... 124 Annex H (informative)

Shaft voltages resulting in motor bearing or shaft brush sparking Discharge energy calculation ................................................................................ 125 H.1 General ............................................................................................................... 125 H.2 Assessment of the risk of ignition using ignition energy calculation ..................... 125 H.3 Shaft voltage determination for a rotating machine .............................................. 126 H.4 Capacitance “C” calculation for a rotating machine ............................................. 126 H.5 Energy “E” calculation for a rotating machine ...................................................... 129 H.6 Assessment using reference curves .................................................................... 129 Bibliography ........................................................................................................................ 131

Figure 1 – Typical battery examples ...................................................................................... 20 oSIST IEC 60079-0:2018

IEC 60079-0:2017  IEC 2017 – 7 –

Figure 2 – Typical battery compartment ................................................................................ 21 Figure 3 – Typical replaceable battery pack ..........................................................

...

IEC 60079-0
Edition 7.0 2017-12
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Explosive atmospheres –
Part 0: Equipment – General requirements
Atmosphères explosives –
Partie 0: Matériel – Exigences générales
IEC 60079-0:2017-12(en-fr)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC 60079-0
Edition 7.0 2017-12
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Explosive atmospheres –
Part 0: Equipment – General requirements
Atmosphères explosives –
Partie 0: Matériel – Exigences générales
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.260.20 ISBN 978-2-8322-5065-5

Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 3 ----------------------
IEC 60079-0:2017/ISH1:2019 – 1 –
 IEC 2019
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
IEC 60079-0
Edition 7.0 2017-12
EXPLOSIVE ATMOSPHERES –
Part 0: Equipment – General requirements
INTERPRETATION SHEET 1

This interpretation sheet has been prepared by IEC technical committee 31: Equipment for

explosive atmospheres.
The text of this interpretation sheet is based on the following documents:
DISH Report on voting
31/1455/DISH 31/1464/RVDISH

Full information on the voting for the approval of this interpretation sheet can be found in the

report on voting indicated in the above table.
___________
Interpretation sheet of Subclause 16.6 of IEC 60079-0:2017

The TC31/CAG requested (Resolution 2 of 2018-04-19) that WG22 prepare an interpretation

sheet based on IECEx Decision Sheet DS2018/002 addressing the assignment of entry point

and branching point temperatures of electrical rotating machines.
Details of interpretation:
IEC 60079-0:2017 (Ed. 7), Explosive atmospheres – Part 0: Equipment – General
requirements

Interpretation of Subclause 16.6: Temperature at branching point and entry point:

Question: Subclause 16.6 of IEC 60079-0:2017 states “When the temperature under rated

conditions is higher than 70 °C at the entry point or 80 °C at the branching point of the

conductors, information shall be marked on the equipment exterior to provide guidance to the

user on the proper selection of cable and cable gland or conductors in conduit.”
ICS 29.260.20
IEC 60079-0:2017-12/ISH1:2019-04(en)
---------------------- Page: 4 ----------------------
– 2 – IEC 60079-0:2017/ISH1:2019
 IEC 2019

It is not normal practice for electrical rotating machines to be tested with the cable entry

devices and cables that might be used in an actual installation, but with the cables available

at the manufacturer’s test area. In many cases, there will be no formal entry device as the

cables will enter via the space reserved for fixing of a gland plate.

How shall the relevant entry point and branching point temperatures be determined?

Interpretation: The use of the maximum internal air space temperature to represent the

maximum service temperature of terminal box gaskets and seals, the cable branching point

temperature, and the entry point temperature reflects the normal practice of testing electrical

rotating machines without prior knowledge of the actual glands and cables to be used for

installation. The production of heat from the electrical rotating machine connections is

generally insignificant with respect to the production of heat from the machine windings and

core.
Further amplification:

1) The entry point of the cable where the temperature is measured should be sealed so far

as possible to ensure that there is minimum air-circulation which can reduce the measured

temperature.

2) This is not intended to apply to any gasket between the terminal box and the frame of the

electrical rotating machine, where higher temperatures may be recorded, but only to the

gasket between the terminal box and its lid.

Although written in the context of electrical rotating machines, there may be other types of

equipment where an equivalent approach is applicable
---------------------- Page: 5 ----------------------
IEC 60079-0:2017/ISH2:2019 – 1 –
 IEC 2019
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
IEC 60079-0
Edition 7.0 2017-12
EXPLOSIVE ATMOSPHERES –
Part 0: Equipment – General requirements
INTERPRETATION SHEET 2

This interpretation sheet has been prepared by IEC technical committee 31: Equipment for

explosive atmospheres.
The text of this interpretation sheet is based on the following documents:
DISH Report on voting
31/1469/DISH 31/1486/RVDISH

Full information on the voting for the approval of this interpretation sheet can be found in the

report on voting indicated in the above table.
___________
Question:

How shall marking be shown for equipment covered by both the electrical and non-electrical

standards (IEC 60079 and ISO 80079 series)?
Answer:

Equipment which includes both an electrical part and a non-electrical part shall have

combined marking. For example:
Ex db h IIA T4 Gb
Ex h tb IIIC T135 °C Db
ICS 29.260.20
IEC 60079-0:2017-12/ISH2:2019-06(en-fr)
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– 2 – IEC 60079-0:2017/ISH2:2019
 IEC 2019

It will be clearer for the user that the combined risk of the electrical part and the non-electrical

part, covered by a single certificate, has been assessed for the complete equipment, stating

one EPL, one equipment Group and one temperature class for Gas and the same for Dust

(but showing a maximum surface temperature instead of a temperature class). It is also noted

that Ex Components are not marked with either a temperature class (Group II) or a maximum

surface temperature (Group III).

For equipment where separate certificates have been prepared, with one for the electrical

parts, and one for the non-electrical parts, it is appropriate to have separate electrical and

non-electrical marking strings, each with its own associated certificate number.

NOTE Additional guidance on the marking of assemblies is given in IEC TS 60079-46.

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– 2 – IEC 60079-0:2017  IEC 2017
CONTENTS

FOREWORD ........................................................................................................................... 8

1 Scope ............................................................................................................................ 15

2 Normative references .................................................................................................... 16

3 Terms and definitions .................................................................................................... 18

4 Equipment grouping ....................................................................................................... 36

4.1 General ................................................................................................................. 36

4.2 Group I ................................................................................................................. 36

4.3 Group II ................................................................................................................ 36

4.4 Group III ............................................................................................................... 36

4.5 Equipment for a particular explosive gas atmosphere ............................................ 37

5 Temperatures ................................................................................................................ 37

5.1 Environmental influences ...................................................................................... 37

5.1.1 Ambient temperature ..................................................................................... 37

5.1.2 External source of heating or cooling ............................................................. 37

5.2 Service temperature .............................................................................................. 37

5.3 Maximum surface temperature .............................................................................. 38

5.3.1 Determination of maximum surface temperature ............................................ 38

5.3.2 Limitation of maximum surface temperature ................................................... 38

5.3.3 Small component temperature for Group I or Group II electrical

equipment...................................................................................................... 39

5.3.4 Component temperature of smooth surfaces for Group I or Group II

electrical equipment ....................................................................................... 40

6 Requirements for all equipment ..................................................................................... 41

6.1 General ................................................................................................................. 41

6.2 Mechanical strength of equipment ......................................................................... 41

6.3 Opening times ....................................................................................................... 41

6.4 Circulating currents in enclosures (e.g. of large electric machines) ....................... 42

6.5 Gasket retention ................................................................................................... 42

6.6 Electromagnetic and ultrasonic energy radiating equipment .................................. 42

6.6.1 General ......................................................................................................... 42

6.6.2 Radio frequency sources ............................................................................... 42

6.6.3 Ultrasonic sources ......................................................................................... 43

6.6.4 Lasers, luminaires, and other non-divergent continuous wave optical

sources.......................................................................................................... 44

7 Non-metallic enclosures and non-metallic parts of enclosures ....................................... 44

7.1 General ................................................................................................................. 44

7.1.1 Applicability ................................................................................................... 44

7.1.2 Specification of materials ............................................................................... 44

7.2 Thermal endurance ............................................................................................... 45

7.2.1 Tests for thermal endurance .......................................................................... 45

7.2.2 Material selection .......................................................................................... 46

7.2.3 Alternative qualification of elastomeric sealing O-rings .................................. 46

7.3 Resistance to ultraviolet light ................................................................................ 46

7.4 Electrostatic charges on external non-metallic materials ....................................... 47

7.4.1 Applicability ................................................................................................... 47

7.4.2 Avoidance of a build-up of electrostatic charge for Group I or Group II .......... 47

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IEC 60079-0:2017  IEC 2017 – 3 –

7.4.3 Avoidance of a build-up of electrostatic charge for Group III .......................... 49

7.5 Attached external conductive parts ....................................................................... 50

8 Metallic enclosures and metallic parts of enclosures ...................................................... 51

8.1 Material composition ............................................................................................. 51

8.2 Group I ................................................................................................................. 51

8.3 Group II ................................................................................................................ 51

8.4 Group III ............................................................................................................... 52

8.5 Copper Alloys ....................................................................................................... 52

9 Fasteners ...................................................................................................................... 52

9.1 General ................................................................................................................. 52

9.2 Special fasteners .................................................................................................. 53

9.3 Holes for special fasteners .................................................................................... 53

9.3.1 Thread engagement ....................................................................................... 53

9.3.2 Tolerance and clearance ............................................................................... 53

9.4 Hexagon socket set screws ................................................................................... 54

10 Interlocking devices ....................................................................................................... 54

11 Bushings ....................................................................................................................... 54

12 (Reserved for future use) ............................................................................................... 54

13 Ex Components ............................................................................................................. 54

13.1 General ................................................................................................................. 54

13.2 Mounting ............................................................................................................... 55

13.3 Internal mounting .................................................................................................. 55

13.4 External mounting ................................................................................................. 55

13.5 Ex Component certificate ...................................................................................... 55

14 Connection facilities ...................................................................................................... 55

14.1 General ................................................................................................................. 55

14.2 Type of protection ................................................................................................. 56

14.3 Creepage and clearance ....................................................................................... 56

15 Connection facilities for earthing or bonding conductors ................................................ 56

15.1 Equipment requiring earthing or bonding ............................................................... 56

15.1.1 Internal earthing ............................................................................................ 56

15.1.2 External bonding............................................................................................ 56

15.2 Equipment not requiring earthing .......................................................................... 56

15.3 Size of protective earthing conductor connection .................................................. 56

15.4 Size of equipotential bonding conductor connection .............................................. 57

15.5 Protection against corrosion .................................................................................. 57

15.6 Secureness of electrical connections .................................................................... 57

15.7 Internal earth continuity plate ................................................................................ 57

16 Entries into enclosures .................................................................................................. 57

16.1 General ................................................................................................................. 57

16.2 Identification of entries .......................................................................................... 57

16.3 Cable glands ......................................................................................................... 58

16.4 Blanking elements................................................................................................. 58

16.5 Thread adapters ................................................................................................... 58

16.6 Temperature at branching point and entry point .................................................... 59

16.7 Electrostatic charges of cable sheaths .................................................................. 59

17 Supplementary requirements for electric machines ........................................................ 60

17.1 General ................................................................................................................. 60

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– 4 – IEC 60079-0:2017  IEC 2017

17.2 Ventilation............................................................................................................. 60

17.2.1 Ventilation openings ...................................................................................... 60

17.2.2 Materials for external fans ............................................................................. 60

17.2.3 Cooling fans of rotating electric machines ...................................................... 60

17.2.4 Auxiliary motor cooling fans ........................................................................... 61

17.2.5 Room ventilating fans .................................................................................... 61

17.3 Bearings ............................................................................................................... 62

18 Supplementary requirements for switchgear .................................................................. 62

18.1 Flammable dielectric ............................................................................................. 62

18.2 Disconnectors ....................................................................................................... 62

18.3 Group I – Provisions for locking ............................................................................ 63

18.4 Doors and covers .................................................................................................. 63

19 Reserved for future use ................................................................................................. 63

20 Supplementary requirements for external plugs, socket outlets and connectors for

field wiring connection ................................................................................................... 63

20.1 General ................................................................................................................. 63

20.2 Explosive gas atmospheres .................................................................................. 64

20.3 Explosive dust atmospheres ................................................................................. 64

20.4 Energized plugs .................................................................................................... 64

21 Supplementary requirements for luminaires ................................................................... 64

21.1 General ................................................................................................................. 64

21.2 Covers for luminaires of EPL Mb, EPL Gb, or EPL Db ........................................... 64

21.3 Covers for luminaires of EPL Gc or EPL Dc .......................................................... 65

21.4 Sodium lamps ....................................................................................................... 65

22 Supplementary requirements for caplights and handlights ............................................. 65

22.1 Group I caplights .................................................................................................. 65

22.2 Group II and Group III caplights and handlights ................................................... 65

23 Equipment incorporating cells and batteries ................................................................... 66

23.1 General ................................................................................................................. 66

23.2 Interconnection of cells to form batteries ............................................................... 66

23.3 Cell types .............................................................................................................. 66

23.4 Cells in a battery ................................................................................................... 69

23.5 Ratings of batteries ............................................................................................... 69

23.6 Interchangeability ................................................................................................. 69

23.7 Charging of primary batteries ................................................................................ 69

23.8 Leakage ................................................................................................................ 69

23.9 Connections .......................................................................................................... 69

23.10 Orientation ............................................................................................................ 69

23.11 Replacement of cells or batteries .......................................................................... 69

23.12 Replaceable battery pack ...................................................................................... 70

24 Documentation .............................................................................................................. 70

25 Compliance of prototype or sample with documents ....................................................... 70

26 Type tests ..................................................................................................................... 70

26.1 General ................................................................................................................. 70

26.2 Test configuration ................................................................................................. 70

26.3 Tests in explosive test mixtures ............................................................................ 70

26.4 Tests of enclosures ............................................................................................... 71

26.4.1 Order of tests ................................................................................................ 71

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IEC 60079-0:2017  IEC 2017 – 5 –

26.4.2 Resistance to impact ..................................................................................... 73

26.4.3 Drop test ....................................................................................................... 74

26.4.4 Acceptance criteria ........................................................................................ 75

26.4.5 Degree of protection (IP) by enclosures ......................................................... 75

26.5 Thermal tests ........................................................................................................ 76

26.5.1
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