ansi+isa+12.00.01-1999+-+(iec+60079-0+mod)

S T A N D A R D

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ISA–S12.00.01–1999 (IEC 60079-0 Mod)

Electrical Apparatus for Use

in Class I, Zones 0, 1, & 2Hazardous (Classified)Locations —General Requirements

Approved 15 July 1999

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ISA–S12.00.01–1999Electrical Apparatus for Use in Class I, Zones 0, 1 & 2 Hazardous (Classified) Locations:General Requirements

ISBN: 1-55617-710-0

Copyright 1999 by the Instrument Society of America. All rights reserved. Not for resale. Printed in theUnited States of America. No part of this publication may be reproduced, stored in a retrieval system, ortransmitted, in any form or by any means (electronic, mechanical, photocopying, recording, or otherwise),without the prior written permission of the Publisher.

ISA67 Alexander DriveP. O. Box 12277Research Triangle Park, North Carolina 27709

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Preface

This ISA standard is based on IEC Publication 60079-0. It is the intention of the ISA SP12 Committee todevelop an ANSI Standard that is harmonized with IEC 60079-0 to the fullest extent possible.

This preface is included for informational purposes and is not part of ISA-S12.00.01 (IEC 60079-0 Mod).The suffix "Mod" indicates the document is a modification of the IEC document and includes US deviationsencompassing both additions and deletions of information.

This Standard has been prepared as part of the service of ISA, the international society for measurementand control, toward a goal of uniformity in the field of instrumentation. To be of real value, this documentshould not be static but should be subject to periodic review. Toward this end, the Society welcomes allcomments and criticisms and asks that they be addressed to the Secretary, Standards and PracticesBoard; ISA; 67 Alexander Drive; P. O. Box 12277; Research Triangle Park, NC 27709; Telephone (919)990-9227; Fax (919) 549-8288; Internet: [email protected].

The ISA Standards and Practices Department is aware of the growing need for attention to the metricsystem of units in general, and the International System of Units (SI) in particular, in the preparation ofinstrumentation standards. The Department is further aware of the benefits to USA users of ISA standardsof incorporating suitable references to the SI (and the metric system) in their business and professionaldealings with other countries. Toward this end, this Department will endeavor to introduce SI-acceptablemetric units in all new and revised standards, recommended practices, and technical reports to thegreatest extent possible. Standard for Use of the International System of Units (SI): The Modern MetricSystem, published by the American Society for Testing & Materials as IEEE/ASTM SI 10-97, and futurerevisions, will be the reference guide for definitions, symbols, abbreviations, and conversion factors.

It is the policy of ISA to encourage and welcome the participation of all concerned individuals and interestsin the development of ISA standards, recommended practices, and technical reports. Participation in theISA standards-making process by an individual in no way constitutes endorsement by the employer of thatindividual, of ISA, or of any of the standards, recommended practices, and technical reports that ISAdevelops.

CAUTION — ISA ADHERES TO THE POLICY OF THE AMERICAN NATIONAL STANDARDSINSTITUTE WITH REGARD TO PATENTS. IF ISA IS INFORMED OF AN EXISTING PATENT THAT ISREQUIRED FOR USE OF THE STANDARD, IT WILL REQUIRE THE OWNER OF THE PATENT TOEITHER GRANT A ROYALTY-FREE LICENSE FOR USE OF THE PATENT BY USERS COMPLYINGWITH THE STANDARD OR A LICENSE ON REASONABLE TERMS AND CONDITIONS THAT AREFREE FROM UNFAIR DISCRIMINATION.

EVEN IF ISA IS UNAWARE OF ANY PATENT COVERING THIS STANDARD, THE USER ISCAUTIONED THAT IMPLEMENTATION OF THE STANDARD MAY REQUIRE USE OF TECHNIQUES,PROCESSES, OR MATERIALS COVERED BY PATENT RIGHTS. ISA TAKES NO POSITION ON THEEXISTENCE OR VALIDITY OF ANY PATENT RIGHTS THAT MAY BE INVOLVED IN IMPLEMENTINGTHE STANDARD. ISA IS NOT RESPONSIBLE FOR IDENTIFYING ALL PATENTS THAT MAYREQUIRE A LICENSE BEFORE IMPLEMENTATION OF THE STANDARD OR FOR INVESTIGATINGTHE VALIDITY OR SCOPE OF ANY PATENTS BROUGHT TO ITS ATTENTION. THE USER SHOULDCAREFULLY INVESTIGATE RELEVANT PATENTS BEFORE USING THE STANDARD FOR THEUSER’S INTENDED APPLICATION.

HOWEVER, ISA ASKS THAT ANYONE REVIEWING THIS STANDARD WHO IS AWARE OF ANYPATENTS THAT MAY IMPACT IMPLEMENTATION OF THE STANDARD NOTIFY THE ISASTANDARDS AND PRACTICES DEPARTMENT OF THE PATENT AND ITS OWNER.


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ADDITIONALLY, THE USE OF THIS STANDARD MAY INVOLVE HAZARDOUS MATERIALS,OPERATIONS OR EQUIPMENT. THE STANDARD CANNOT ANTICIPATE ALL POSSIBLEAPPLICATIONS OR ADDRESS ALL POSSIBLE SAFETY ISSUES ASSOCIATED WITH USE INHAZARDOUS CONDITIONS. THE USER OF THIS STANDARD MUST EXERCISE SOUNDPROFESSIONAL JUDGMENT CONCERNING ITS USE AND APPLICABILITY UNDER THE USER’SPARTICULAR CIRCUMSTANCES. THE USER MUST ALSO CONSIDER THE APPLICABILITY OF ANYGOVERNMENTAL REGULATORY LIMITATIONS AND ESTABLISHED SAFETY AND HEALTHPRACTICES BEFORE IMPLEMENTING THIS STANDARD.

The following people served as members of ISA SP12.0:

NAME COMPANY

W. Lawrence, Chair* Factory Mutual Research Corp.A. Ballard Crouse-Hinds Division, Cooper IndustriesA. Engler EGS Electrical GroupT. Feindel R. Stahl, Inc.D. Jagger HAWKE AmericaJ. Kuczka KillarkN. Ludlam* Factory Mutual Research Corp.K. McManama Underwriters Laboratories Inc.T. Schnaare Rosemount, Inc.

The following people served as members of ISA Committee SP12:

NAME COMPANY

F. McGowan, Chairman* Factory Mutual Research Corp.D. Bishop, Managing Director* Chevron Production Technology CompanyN. Abbatiello* Eastman Kodak CompanyS. Arnold Drexelbrook Engineering CompanyP. Babiarz* Crouse-Hinds Division, Cooper IndustriesA. Ballard* Crouse-Hinds Division, Cooper IndustriesG. Bentinck Dupont EngineeringR. Berthold* Chevron Petroleum Technology CompanyK. Blayden Upjohn CompanyH. Bockle Killark-Stahl, Inc.J. Bossert Hazloc, Inc.R. Brodin Fisher Controls International, Inc.M. Buettner Ralston Purina CompanyR. Buschart PC & E, Inc.W. Calder III* Factory Mutual Research Corp.R. Cardinal Bently Nevada Corp.R. Castillo Corpoven SAH. Conner ConsultantM. Coppler AmetekJ. Cospolich Waldemar S. Nelson & Company, Inc.J. Costello Henkel Corp.E. Cranch* Drexelbrook Engineering CompanyA. Czyz INERISW. Dill DMT

______* One vote per company.


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U. Dugar Mobil Chemical CompanyA. Engler* EGS Electrical GroupT. Feindel R. Stahl, Inc.W. Fiske Inchcape Testing ServicesS. Florence Motorola Inc.G. Garcha PCS EngineeringB. Gibson ABB Kent-Taylor, Inc.J. Greenwald Rexene Corp.E. Henning Fischer & Porter CompanyD. Hohenstein Pepperl + FuchsD. Jagger Hawke AmericaX. Jianping Shanghai Inst. of Process Automation Instr.P. Kelly* Underwriters Laboratories, Inc.F. Kent* Honeywell, Inc.J. Kuczka KillarkT. Lagana BE&K Inc.R. Landman International Marine Products Inc.B. Larson* Turck Inc.W. Lawrence* Factory Mutual Research Corp.W. Leber* EGS Electrical GroupT. Lewis, Jr. Applied AutomationD. Li Canadian Standards AssociationV. Maggioli Feltronics Corp.E. Magison* ConsultantF. Maltby* Drexelbrook Engineering CompanyR. Masek Bailey Controls CompanyD. McDermott Dexion HouseI. McMurchie OPC Engineering Inc.R. McNeal Hawke AmericaJ. Miller Detector Electronics Corp.A. Mobley* 3M CompanyW. Mueller* Pepperl + Fuchs, Inc.E. Nesvig Erdco Engineering Corp.E. Olson* 3M CompanyA. Page III MSHA Certification CenterJ. Propst Shell Development CompanyC. Sandberg Raychem Corp.J. Schaeffer Endress & HauserP. Schimmoeller* Factory Mutual Research CorporationT. Schnaare Rosemount, Inc.A. Stafford Foxboro CompanyD. Stevens* Chevron Petroleum Technology CompanyD. Styrcula* Underwriters Laboratories Inc.J. Thomason OMNI Industrial Systems, Inc.P. Thurnherr Thuba, Ltd.L. Truscott Motorola, Inc.P. Turner* 3M CompanyT. Vu Milltronics Inc.D. Wechsler Union Carbide Corp.R. Weinzler* Eastman Kodak CompanyZ. Zborovszky U.S. Bureau of Mines

______* One vote per company.


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This standard was approved for publication by the ISA Standards and Practices Board on 15 July 1999.

NAME COMPANY

H. Dammeyer The Ohio State UniversityH. Baumann H. D. Baumann, Inc.D. Bishop Chevron Petroleum Technology Co.P. Brett Honeywell, Inc.M. Cohen Senior Flexonics, Inc.M. Coppler Ametek, Inc.W. Holland Southern CompanyA. Iverson Ivy OptiksR. Jones Dow Chemical Co.V. Maggioli Feltronics Corp.T. McAvinew Instrumentation & Control Engineering LLCA. McCauley, Jr. Chagrin Valley Controls, Inc.R. McFarland Honeywell, Inc.R. Reimer Rockwell AutomationJ. Rennie Factory Mutual Research Corp.R. Webb Altran Corp.W. Weidman Parsons Energy & Chemicals GroupJ. Weiss EPRIJ. Whetstone National Institute of Standards & TechnologyM. Widmeyer ConsultantR. Wiegle CANUS Corp.C. Williams Eastman Kodak Co.G. Wood Graeme Wood ConsultingM. Zielinski Fisher-Rosemount Systems, Inc.


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Contents

Foreword ............................................................................................................................................... 9

1 Scope ............................................................................................................................................. 11

2 Normative References.................................................................................................................... 11

3 Definitions and symbols.................................................................................................................. 14

4 Apparatus grouping and temperature classification ....................................................................... 16

5 Temperatures ................................................................................................................................. 17

6 General........................................................................................................................................... 19

7 Non-metallic enclosures and non-metallic parts of enclosures ...................................................... 19

8 Enclosures containing light metals ................................................................................................. 21

9 Fasteners........................................................................................................................................ 22

10 Interlocking devices ...................................................................................................................... 24

11 Bushings....................................................................................................................................... 24

12 Materials used for cementing ....................................................................................................... 24

13 Ex components............................................................................................................................. 24

14 Connection facilities and terminal compartments ......................................................................... 25

15 Connection facilities for earthing or bonding conductors.............................................................. 25

16 Cable and conduit entries............................................................................................................. 26

17 Rotating electrical machines......................................................................................................... 28

18 Supplementary requirements for switchgear ................................................................................ 29

19 Supplementary requirements for fuses......................................................................................... 30

20 Supplementary requirements for plugs and sockets .................................................................... 30

21 Supplementary requirements for luminaires................................................................................. 30

22 Supplementary requirements for caplights, caplamps and handlamps ........................................ 31

23 Type verifications and tests .......................................................................................................... 32

24 Routine verifications and tests...................................................................................................... 39

25 Manufacturer's responsibility ........................................................................................................ 39

26 Verifications and tests on modified or repaired electrical apparatus ............................................ 40

27 Marking......................................................................................................................................... 40

Annex A (informative) — Subdivision of gases and vapours according to their maximumexperimental safe gaps and minimum ignition currents ...................................................................... 45

Annex B (normative) — Ex cable entries (glands or fittings) ............................................................... 51

Annex C (normative) — Ex components ............................................................................................. 59


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Annex D (informative) — Example of rig for resistance to impact test ................................................ 61

Annex E (informative) — Common standards - safety requirements for electrical equipiment ........... 63

Annex F (informative) — United States Major Deviations ................................................................... 67


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Foreword

All text of IEC 60079-0:1998 is included. U.S. National Deviations are shown by strikeout through textdeleted and underline under text added. Tables, or portions of tables, that are to be deleted are shown asshaded; figures to be deleted are marked with the overlay "X." There are six annexes in this Standard.Annexes A, D, E, and F are informative and are not considered part of this Standard. Annexes B, and Care Normative and are considered part of this Standard.


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1 Scope

This standard specifies the general requirements for construction, testing and marking of electricalapparatus, Ex cable entries and Ex components, intended for use in potentially explosive atmospheres ofgas, vapor and mist defined as Class I, Zone 0, 1 or 2 by the National Electrical Code, NFPA 70.

This standard does not specify requirements for safety, other than those directly related to the explosionrisk.

Apparatus covered by this standard and the associated standards noted below shall also comply with theapplicable requirements for similar apparatus for use in unclassified locations. A list of commonly appliedstandards is shown in informative annex E.

NOTE Requirements for safety of electrical equipment in ordinary (unclassified) locations can be found in ANSI Standards, NEMAStandards, Federal Regulations, etc.

This standard is or will be supplemented or modified by the following standards parts of IEC 60079concerning specific types of protection:

• Flameproof enclosures ‘d’, IEC 60079-1 (ISA-S12.22.01-1998 [IEC 60079-1 Mod]);

• Pressurized enclosures ‘p’, IEC 60079-2; see Note 3;

• Powder-filling ‘q’, IEC 60079-5 (ISA-S12.25.01-1998 [IEC 60079-5 Mod]);

• Oil-immersion ‘o’, IEC 60079-6 (ISA-S12.26.01-1998 [IEC 60079-6 Mod]);

• Increased safety ‘e’, IEC 60079-7 (ISA-S12.16.01-1998 (IEC 60079-7 Mod));

• Intrinsic safety ‘i’, IEC 60079-11 (ISA-S12.02.01-1999 [IEC 60079-11 Mod]);

• Encapsulation ‘m’, IEC 60079-18 (ISA-S12.23.01-1998 [IEC 60079-18 Mod]).

• Caplights for mines susceptible to firedamp - under consideration.

This part of IEC 60079 standard and the parts of IEC 60079 mentioned above above documents are notapplicable to the construction of electromedical apparatus, shot-firing exploders, test devices for explodersand for shot-firing circuits.

NOTE 1 — In addition to the types of protection listed above, IEC 60079-15 (ISA dS12.12.02 [IEC 60079-15 Mod]), is applicable foruse in potentially explosive atmospheres.

NOTE 2 — Apparatus not conforming with this standard or the standards listed in this clause, may be considered safe by a national orother authorised body for use in potentially explosive atmospheres. In such cases, the apparatus is identified with the symbol 's'.

NOTE 3 — The requirements for pressurization can be found in ANSI/NFPA 496, “Pressurized Enclosures for Electrical Equipment,”along with additional guidance in ISA-RP12.4-1996, “Pressurized Enclosures.”

2 Normative References

The following normative documents may contain provisions, which, through reference in this text,constitute provisions of this International Standard. At the time of publication, the editions indicated werevalid. All normative documents are subject to revision, and parties to agreements based on thisInternational Standard are encouraged to investigate the possibility of applying the most recent editions ofthe normative documents indicated below. Members of IEC and ISO maintain registers of currently validInternational Standards. ANSI maintains registers of currently valid US National Standards.


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ANSI/NFPA 70:1999 National Electrical Code

ÿþýüûþúùÿø÷öõ Pressurized Enclosures for Electrical Equipment

ANSI/NFPA 497 Classification of Flammable Liquids, Gases or Vapors and ofHazardous (Classified) Locations for Electrical Installations inChemical Process Areas

ANSI/UL 746B Standard for Polymeric Materials – Long-Term PropertyEvaluations

IEC 60034-5: 1991 Rotating electrical machines Part 5: Classification of degrees ofprotection provided by enclosures of rotating electrical machines(IP Code)

IEC 60079-1: 1990 Electrical apparatus for explosive gas atmospheres Part 1:Construction and verification test of flameproof enclosures ofelectrical apparatus

ISA S12.22.01 (IEC 60079-1 Mod) Electrical Apparatus for Use in Class I, Zone 1 Hazardous(Classified) Locations Type of Protection — Flameproof “d”

IEC 60079-2: 1983 Electrical apparatus for explosive gas atmospheres Part 2:Electrical apparatus, type of protection 'p'

IEC 60079-3: 1990 Electrical apparatus for explosive gas atmospheres Part 3:Spark-test apparatus for intrinsically safe circuits

IEC 60079-4: 1975 Electrical apparatus for explosive gas atmospheres Part 4:Method of test for ignition temperature

IEC 60079-5: 1996 Electrical apparatus for explosive gas atmospheres Part 5:Powder filling 'q'

ISA S12.26.01 (IEC 60079-6 Mod) Electrical Apparatus for Use in Class I, Zone 1 Hazardous(Classified) Locations: Type of Protection — Oil-Immersion “o”

IEC 60079-6: 1995 Electrical apparatus for explosive gas atmospheres Part 6: Oil-Immersion 'o'

ISA S12.25.01 (IEC 60079-5 Mod) Electrical Apparatus for Use in Class I, Zone 1 Hazardous(Classified) Locations: Type of Protection — Powder Filling “q”

IEC 60079-7: 1990 Electrical apparatus for explosive gas atmospheres Part 7:Increased safety 'e'

ISA S12.16.01 (IEC 60079-7 Mod) Electrical Apparatus for Use in Class I, Zone 1 Hazardous(Classified) Locations: Type of Protection — IncreasedSafety “e”

IEC 60079-11: 1991 Electrical apparatus for explosive gas atmospheres Part 11:Intrinsic safety 'i'


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ISA S12.2.01 (IEC 60079-11 Mod) Electrical Apparatus for Use in Class I, Zones 0, 1, & 2Hazardous (Classified) Locations: Intrinsic Safety “i”

IEC 60079-15: 1987 Electrical apparatus for explosive gas atmospheres Part 15:electrical apparatus with type of protection 'n'

ISA S12.12.01 (IEC 60079-15 Mod) Electrical Apparatus for Use in Class I, Zone 2 Hazardous(Classified) Locations: Type of Protection — “n”

IEC 60079-18: 1992 Electrical apparatus for explosive gas atmospheres Part 18:Encapsulation'm'

ISA S12.23.01 (IEC 60079-18 Mod) Electrical Apparatus for Use in Class I, Zone 1 Hazardous(Classified) Locations: Type of Protection — Encapsulation “m”

IEC 60079-20: 1996 Electrical apparatus for explosive gas atmospheres, Part 20:Data for flammable gases and vapours, relating to the use ofelectrical apparatus

IEC 60192: 1973 Low pressure sodium vapour lamps

IEC 60216-1: 1990 Guide for the determination of thermal endurance properties ofelectrical insulating materials Part 1: General guidelines foraging procedure and evaluation of test results

IEC 60216-2: 1990 Guide for the determination of thermal endurance properties ofelectrical insulating materials Part 2: Choice of test criteria

IEC 60529: 1989 Degrees of protection provided by enclosures (IP Code)

IEC 60662: 1980 High-pressure sodium vapour lamps

ISO 60048: 1979 Vulcanized rubbers - Determination of hardness (hardnessbetween 30 and 85 IRHD)

ISA RP12.4 Pressurized Enclosures

ISO 60178: 1975 Plastics - Determination of flexural properties of rigid plastics

ISO 60179: 1982 Plastics - Determination of Charpy impact strength of rigidmaterials

ISO 60262: 1973 ISO general purpose metric screw threads - Selected sizes forscrews, bolts and nuts

ISO 60273: 1979 Fasteners - Clearance Holes for bolts and screws

ISO 60286-2: 1988 ISO system of limits and fits - Part 2 Tables of standard tolerancegrades and limit deviations for holes and shafts

ISO R 60527: 1966 Plastics - Determination of tensile properties

ISO 60965-1: 1980 ISO general purpose metric screw threads - Tolerances - Part 1:Principles and basic data


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ISO 60965-2: 1980 ISO general purpose metric screw threads - Tolerances - Part 2:Limits of sizes for general purpose bolt and nut threads - mediumquality

ISO 61817: 1985 Rubber, vulcanized - Determination of the effect of liquids

ISO 61818: 1975 Vulcanized rubbers of low hardness (10 to 35 IRHD) -Determination of hardness

ISO 64014: 1988 Hexagon head bolts - Product grades A and B

ISO 64017: 1988 Hexagon head screws - Product grades A and B

ISO 64026: 1977 Hexagon socket set screws with flat point

ISO 64027: 1977 Hexagon socket set screws with cone point

ISO 64028: 1977 Hexagon socket set screws with dog point

ISO 64029: 1977 Hexagon socket set screws with cup point

ISO 64032: 1986 Hexagon nuts, style 1 - Product grades A and B

ISO 64762: 1989 Hexagon socket head cap screws - Product grade A

ISO 64892: 1981 Plastics - Methods of exposure to laboratory light sources

3 Definitions and symbols

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

3.1 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, andconsumption of electrical energy and items for telecommunications.

3.2 potentially explosive atmosphere:an atmosphere which could become explosive (the danger is a potential one).

3.3 explosive gas atmosphere:a mixture with air, under atmospheric conditions, of flammable substances in the form of gas, vapour ormist, in which after ignition, combustion spreads throughout the unconsumed mixture.

3.4 explosive test mixture:a specified explosive mixture used for the testing of electrical apparatus for potentially explosiveatmospheres.

3.5 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.

3.6 service temperature:the temperature reached when apparatus is operating at its rating.


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3.7 maximum service temperature:the highest value of the service temperatures.

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

3.8 maximum surface temperature:the highest temperature which is attained in service under the most adverse conditions (but within therecognized tolerances) by any part or surface of an electrical apparatus, which would be able to producean 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 thefollowing other conditions: fault conditions specified in the standard for the type of protection concerned; all operating conditionsspecified 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.

3.9 enclosure:all the walls, doors, covers, cable entries, rods, spindles, shafts, etc., which contribute to the type ofprotection of and/or the degree of protection (IP) of the electrical apparatus.

3.10 type of protection:the specific measures applied to electrical apparatus to avoid ignition of a surrounding explosiveatmosphere.

3.11 degree of protection of enclosure (IP):a numerical classification according to IEC 60529 preceded by the symbol IP applied to the enclosure ofelectrical apparatus to provide for:

• protection of persons against contact with or approach to live parts and against contact with movingparts (other than smooth rotating shafts and the like) inside the enclosure, and

• protection of the electrical apparatus against ingress of solid foreign objects and where indicated bythe 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 thetypes of protection listed in clause 1.

3.12 rated value:a quantity value assigned, generally by the manufacturer, for a specified operating condition of acomponent, device or apparatus.

3.13 rating:the set of rated values and operating conditions.

3.14 cable entry:a device permitting the introduction of one or more electric and/or fibre optics cables into an electricalapparatus so as to maintain the relevant type of protection.

3.15 Ex cable entry:a cable entry tested separately from the apparatus enclosure but evaluated certified as apparatus andwhich can be fitted to the apparatus enclosure during installation without further evaluation certification.


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3.16 conduit entry:a means of introducing a conduit into an electrical apparatus so as to maintain the relevant type ofprotection.

3.17 compression element:an element of a cable entry acting on the sealing ring to enable the latter to fulfill its function.

3.18 clamping device:an element of a cable entry for preventing tension or torsion in the cable from being transmitted to theconnections.

3.19 sealing ring:a ring used in a cable or conduit entry to ensure the sealing between the entry and the cable or conduit.

3.20 terminal compartment:a separate compartment or part of a main enclosure, communicating or not with the main enclosure, andcontaining connection facilities.

3.21 connection facilities:terminals screws and other parts used for the electrical connection of conductors of external circuits.

3.22 bushing:an insulating device carrying one or more conductors through an internal or external wall of an enclosure.

3.23 Ex component:a part of electrical apparatus for potentially explosive atmospheres, which is not intended to be used alonein such atmospheres and requires additional evaluation certification when incorporated into electricalapparatus or systems for use in potentially explosive atmospheres.

3.24 "X" symbol:"X" is the symbol used as a suffix to a certificate reference to denote special conditions for safe use.

3.25 "U" symbol:"U" is the 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.

3.26 certificate:a document confirming that the apparatus is in conformity with the requirements, the type tests and, whereappropriate, the routine tests in the standard referred to therein. A certificate can relate to Ex apparatus oran Ex component.

NOTE — A certificate may be produced by the manufacturer, the user, or a third party, for example, an IEC Ex Accepted CertificationBody, a national certification body, or an authorised person.

4 Apparatus grouping and temperature classification

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

• Group 1: Electrical apparatus for mines susceptible to firedamp;

NOTE — Group I electrical apparatus is not within the scope of this ISA Standard.

• Group II: Electrical apparatus for places with a potentially explosive atmosphere, other than minessusceptible to firedamp.


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Electrical apparatus intended for mines where the atmosphere, in addition to firedamp, may containsignificant proportions of other flammable gases (i.e. other than methane), shall be constructed and testedin accordance with the requirements relating to Group I and also to the subdivision of Group IIcorresponding to the other significant flammable gases. This electrical apparatus shall then be markedappropriately (for example "Ex d I/IIB T3" or "Ex d I/II (NH3)").

4.2 Electrical apparatus of Group II may be subdivided according to the nature of the potentially explosiveatmosphere for which it is intended.

4.2.1 For the types of protection flameproof enclosure "d", and intrinsic safety "i", electrical apparatus ofGroup II is subdivided into IIA, IIB and IIC as required in the specific standards concerning these types ofprotection.

NOTE 1 — This subdivision is based on the maximum experimental safe gap (MESG) for flameproof enclosures or the minimumignition current (MIC) for intrinsically safe electrical apparatus (see annex A).

NOTE 2 — Apparatus marked IIB is suitable for applications requiring Group IIA apparatus. Similarly, apparatus IIC is suitable forapplications requiring Group IIA or Group IIB apparatus.

4.2.2 For all types of protection, apparatus of Group II shall be marked as a function of its maximumsurface temperature according to 5.1.2.

4.3 The electrical apparatus may be tested for a particular explosive atmosphere. In this case it shall beevaluated certified and marked accordingly.

5 Temperatures

5.1 Maximum surface temperature

5.1.1 For electrical apparatus of Group I the maximum surface temperature shall be specified in relevantdocumentation according to 23.2.

This maximum surface temperature shall not exceed:

• 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 for safe use.

NOTE — When choosing electrical apparatus of Group I, the user should take into account the influence and the smoulderingtemperature of coal dusts if they are likely to be deposited in a layer on surfaces with temperatures above 150°C.

5.1.2 Group II 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.


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Table 1 — Classification of maximum surface temperatures forGroup II electrical apparatus

5.2 Ambient temperatures

Electrical apparatus shall normally be designed for use in the ambient temperature range between –20°Cand +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 isconsidered to be special; the ambient temperature range shall then be stated by the manufacturer, andspecified in the certificate; the marking shall then include either the symbol Ta or Tamb together with thespecial range of ambient temperatures or, if this is impracticable, the symbol X shall be placed after thecertificate reference, according to 27.2 i) (see table 2).

Table 2 - Ambient temperatures in service and additional marking

5.3 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, theirsurface temperature may exceed that for the temperature class marked on the electrical apparatus forGroup II or the corresponding maximum surface temperature for Group I,if there is no risk of thermalignition from these components. with A safety margin of

• 50 K for TI, T2 and T3;

• 25 K for T4, T5 and T6 and Group I.

This safety margin of shall be ensured by experience of similar components or by tests of the electricalapparatus itself in representative explosive mixtures.

NOTE — During the tests, the safety margin may be provided by increasing the ambient temperature.

Temperature class Maximum surface temperature°C

T1T2T3T4T5T6

45030020013510085

Electrical Apparatus Ambient temperature in service Additional marking

NormalMaximum: + 40°CMinimum: - 20°C

None

SpecialStated by the manufacturer and

specified in the certificate

Ta or Tamb

with the special range, for example:-30°C ≤ Ta ≤ +40°C

or the symbol X


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More specific relaxations for the surface temperature of small components, such as are used in "i" circuits,are given in IEC 60079-11 ISA-S12.02.01-1999 (IEC 60079-11 Mod).

6 General

6.1 Electrical apparatus for use in potentially explosive atmospheres shall comply with the requirementsof 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, humidityeffects, ambient temperature variations, effects of chemical agents, corrosion) these have to be specified to the manufacturer by theuser. and are not the responsibility of the testing station.

6.2 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 ofresidual 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 temperatureclass of the electrical apparatus shall either be marked with the warning:

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 withthe warning:

WARNING — DO NOT OPEN WHEN AN EXPLOSIVE GAS ATMOSPHERE MAY BE PRESENT.

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

7.1 General

The following requirements, and those of 23.4.7, apply to non-metallic enclosures and non-metallic parts ofenclosures on which the type of protection depends.

However, for sealing rings (see 3.19) on which the type of protection depends, the proof furnishedaccording to B.3.3 is sufficient.

7.1.1 The documents according to 23.2 shall specify both the material and the manufacturing process ofthe enclosure or part of the enclosure.

7.1.2 The specification for plastic materials shall include:

a) the name of the manufacturer;

b) the exact and complete reference of the material, including its color, percentage of fillers, and anyother additives if used;


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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 withoutloss of flexural strength exceeding 50%, determined in accordance with IEC 60216-1 and IEC 60216-2and based on the flexing property in accordance with ISO 178. If the material does not break in thistest before exposure to the heat, the index shall be based on the tensile strength in accordance withISO 527-2 with test bars of type 1A or 1B. The relative thermal index (RTI) shall be determined inaccordance with ANSI/UL 746B.

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

7.1.3 The testing station is not required to verify compliance of the material with its definition.

7.2 Thermal endurance

The plastic materials shall have a relative thermal index (RTI) temperature index TI corresponding to the20,000 h point (see 7.1.2) of at least 20 K greater than the temperature of the hottest point of the enclosureor the part of the enclosure (see 23.4.6.1) having regard to the maximum ambient temperature in service(see 5.2).

The endurance to heat and to cold of the enclosures or parts of enclosures of plastic materials shall besatisfactory (see 23.4.7.3 and 23.4.7.4).

7.3 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 otherexposed 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.

7.3.1 Electrical apparatus of Group I

Enclosures of plastic material with surface area projected in any direction of more than 100 cm2 shall be sodesigned that under normal conditions of use, maintenance and cleaning, danger of ignition due toelectrostatic 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 GΩ at (23 ± 2)°C and (50 ± 5)%relative humidity, or by virtue of the size, shape and layout, or other protective methods, such thatdangerous 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 safetymeasures to be applied in service.

NOTE 1 — When selecting electrical insulating materials, attention should be paid to maintaining a minimum insulation resistance toavoid 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 presentcontinuously or is present for long periods.


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7.3.2 Electrical apparatus of Group II

Enclosures shall be so designed that under normal conditions of use, maintenance and cleaning, dangerof ignition due to electrostatic charges is avoided. This requirement shall be satisfied by either of thefollowing:

a) by suitable selection of the material so that the insulation resistance of the enclosure, measured inaccordance to 23.4.7.8, does not exceed 1 GΩ at (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 (seealso note 2):

• for Group IIA and IIB apparatus to a maximum of 100 cm2 except that this may be increased to a

maximum of 400 cm2 if the exposed areas of plastics are surrounded by conductive earthedframes;

• for Group IIC apparatus, including light-transmitting parts, to a maximum of 20 cm2 except that this

may be increased to a maximum of 100 cm2 if the plastic parts are additionally protected againstthe occurrence of dangerous electrostatic charges;

c) or by virtue of the size, shape and lay-out, or other protective methods, such that dangerouselectrostatic 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 thesafety measures to be applied in service.

NOTE 1 — When selecting electrical insulating materials, attention should be paid to maintaining a minimum insulation resistance toavoid 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 presentcontinuously or is present for long periods (zone 0).

7.4 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 threadform is compatible with the plastic material of the enclosure.

8 Enclosures containing light metals

8.1 Materials used in the construction of enclosures of electrical apparatus of Group I shall not contain,by weight:

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

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

NOTE — Values for Group II are under consideration.

8.2 Threaded holes in enclosures for fasteners which secure covers intended to be opened in service foradjustment, inspection, and other operational reasons may only be tapped in the material of the enclosurewhen the thread form is compatible with the material used for the enclosure.

8.3 The provisions of 8.1 do not apply to Group I surveying instruments carried by persons.


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9 Fasteners

9.1 General

Parts necessary to achieve a standard type of protection or used to prevent access to uninsulated liveparts 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 plasticsif the material of the fastener is compatible with that of the enclosure.

9.2 Special fasteners

When any of the standards for a specific standard type of protection requires a special fastener, this shallconform to the following:

• the thread shall be coarse pitch in accordance with ISO 262, with a tolerance fit of 6g/6H inaccordance with ISO 965;

• 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 ofprotection should be protected, for example by the use of shrouds or counter-bored holes.

9.3 Electrical apparatus - holes for special fasteners

9.3.1 Holes for the threaded fasteners of 9.2 shall be threaded for a distance to accept a threadengagement, h, at least equal to the major diameter of the thread of the fastener (see figures 1 and 2).

9.3.2 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 mediumtolerance 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 enablethe fastener to be retained. The dimensions of the threaded hole shall be such that the surroundingsurface in contact with the head of such a fastener shall be at least equal to that of a fastener without areduced shank in a clearance hole (see figure 2).


— 23 —


— 24 —

9.3.3 In the case of hexagon socket set screws the screw head shall have a tolerance fit of 6H inaccordance with ISO 965 but shall not protrude from the threaded hole after tightening.

10 Interlocking devices

Interlocking devices used to maintain a type of protection shall be so constructed that their effectivenesscannot readily be defeated by the use, for example, of a screwdriver or pliers of normally available tools.

11 Bushings

Bushings used as connection facilities, and which may be subjected to a torque while the connection ordisconnection is being made, shall be mounted in such a way that all parts are secured against turning.

The relevant torque test is specified in 23.4.5.

12 Materials used for cementing

12.1 The manufacturer's documents submitted according to 23.2 of this standard shall testify that for theintended operating conditions, the materials used for cementing, and on which safety depends, have athermal stability adequate for the minimum and maximum temperatures to which they will be subjected,within the rating of the electrical apparatus.

The thermal stability is considered adequate if the limiting values for the material are below or equal to thelowest working temperature and at least 20 K above the maximum temperature.

NOTE — If the cementing has to withstand adverse service conditions, appropriate measures should be agreed between user andmanufacturer (see 6.1).

12.2 The testing station is not required to verify the characteristics listed in the documents mentioned in12.1.

13 Ex components

13.1 Ex components shall comply with the requirements given in annex C and may be

a) an empty enclosure;

b) components or assemblies of components for use with apparatus complying with the requirements ofone or more of the types of protection listed in clause 1.

13.2 Ex components may be mounted

a) completely within an apparatus enclosure (for example a type “e” terminal, ammeter, heater orindicator; a type “d” switch component or thermostat, a type “i” supply); or

b) completely external to the apparatus enclosure (for example a type “e” earth terminal, a type “i”sensor); or

c) partly within and partly external to the apparatus enclosure (for example a type “d” push-button switch,a limit switch or indicating lamp, a type “e” ammeter, a type “i” indicator).

13.3 In the case of mounting completely within the enclosure, the only parts to be tested or assessed whenused in an apparatus are those parts which cannot be tested and/or assessed as a separate component


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(for example test or assessment of surface temperature, creepage distance and clearance when thecomponent is mounted).

13.4 In the case of mounting external to the enclosure or partly within and partly external to the enclosure,the interface between the Ex component and the enclosure shall be tested or assessed for compliance withthe relevant type of protection and for compliance with the mechanical tests according to 23.4.3.

14 Connection facilities and terminal compartments

14.1 Electrical apparatus which is intended for connection to external circuits shall include connectionfacilities, except if the electrical apparatus is manufactured with a cable permanently connected to it. Allapparatus constructed with permanently connected unterminated cable shall be marked with the symbol Xto indicate the need for appropriate connection of the free end of the cable.

14.2 Terminal compartments and their access openings shall be dimensioned so that the conductors canbe readily connected.

NOTE — Requirements for wire bending space may be included in the applicable ordinary location standard, e.g., ANSI/UL 508 or inthe National Electrical Code, ANSI/NFPA 70, Section 373-6(b).

14.3 Terminal compartments shall comply with one of the specific standards listed in clause 1.

14.4 Terminal compartments shall be so designed that after proper connection of the conductors, thecreepage distances and the clearances comply with the requirements, if any, of the specific standard for thetype of protection concerned.

NOTE — The ordinary location spacing requirements may be more restrictive than the spacing requirements in the type of protectionstandard.

15 Connection facilities for earthing or bonding conductors

15.1 A connection facility for the connection of an earthing or equipotential bonding conductor shall beprovided inside the terminal compartment of electrical apparatus and near the other connection facilities.

15.2 Electrical apparatus with a metallic enclosure shall have an additional external connection facility foran earthing or equipotential bonding conductor. This external connection facility shall be electrically incontact with the facility required in 15.1. The external connection facility is not required for electricalapparatus which is designed to be moved when energized and is supplied by a cable incorporating anearthing or equipotential bonding conductor.

NOTE — The expression "electrically in contact" does not necessarily involve the use of a conductor.

15.3 Neither An internal nor external earthing or bonding connection facility is not required for electricalapparatus for which earthing (or bonding) is not required, such as electrical apparatus having double orreinforced insulation, or for which supplementary earthing is not necessary.

15.4 Earthing or equipotential bonding (equipment grounding) conductor connection facilities providedinside terminal compartments, or supplemental grounding or bonding terminals provided on the outside ofenclosures, shall allow for the effective connection of at least one conductor with a cross-sectional area asspecified in ANSI/NFPA-70, National Electrical Code, Section 250-122 table 3.


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Table 3 — Minimum cross-sectional areas of protective conductors

When provided, the supplemental grounding and bonding In addition, earthing or bonding connectionfacilities on the outside of electrical apparatus shall provide for effective connection of a conductor of at

least 4 mm2 (10 AWG).

15.5 Connection facilities shall be effectively protected against corrosion. They shall also be designed sothat 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 insulatingmaterials 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 lightmetal. One example of a means of connecting to a material containing light metal is to use an intermediatepart made from steel.

16 Cable and conduit entries

16.1 The manufacturer shall specify in the documents submitted according to 23.2, the entries intendedfor use with cable or conduit, their position on the apparatus and the maximum number permitted.

16.2 Cable and conduit entries shall be constructed and fixed so that they do not alter the specificcharacteristics of the type of protection of the electrical apparatus on which they are mounted. This shallapply to the whole range of cable dimensions specified by the manufacturer of the cable entries as suitablefor use with those entries.

16.3 Cable and conduit entries may form an integral part of the apparatus, i.e. one major element or partforms an inseparable part of the enclosure of the apparatus. In such cases the entries shall be tested andcertified with the apparatus.

NOTE — Cable and conduit entries, which are separate from, but installed with the apparatus, are usually tested and certifiedseparately from the apparatus but may be tested and certified together with the apparatus if the apparatus manufacturer so requests.

16.4 Cable entries (fittings or glands), whether integral or separate, shall meet the relevant requirementsof annex B.

NOTE — The ordinary location requirements for cable entries can be found in ANSI/UL 514B, “Fittings for Conduit and Outlet Boxes.”

16.5 Where the design of a Group I cable entry is such that twisting of the cable can be transmitted to theconnections then an anti-rotation device shall be fitted.

16.6 Provision for entry into the apparatus by conduit shall be either by screwing into threaded holes or bylocking in plain holes:

• in the wall of the enclosure; or

Cross-sectional area of phase conductors of theinstallation S

mm 2

Minimum cross-sectional area of thecorresponding protective conductor Sp

mm 2

16 <

SSS

≤≤>

163535

S16

0.5 S


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• in an adapter plate designed to be fitted in or on the walls of the enclosure; or

• into a suitable stopping box conduit hub, integral with or attached to the wall of the enclosure.

NOTE — Installation documents, e.g., ANSI/NFPA 70 Section 501-16 (a), require grounding type devices when installing conduit inplain holes of metal enclosures.

Threaded holes that are not threaded NPT or provided with adapters to NPT and are intended for theinstallation of conduit or cable entries shall be identified in accordance with 27.9 to indicate the threadform.

16.7 Blanking elements, intended to close openings in the walls of electrical apparatus, when they are notfitted with cable or conduit entries, shall, together with the enclosure wall of the apparatus, satisfy therequirements of the specific type of protection concerned. The means provided for this shall be such thatthe blanking element can be removed only with the aid of a tool.

16.8 When the conductor temperature under rated conditions is higher than 60°C 70°C at the cable orconduit entry point, or 60°C 80°C at the branching point of the conductors, the inside or outside of theelectrical apparatus shall be marked as a guide for the selection by the user of the cable or of the wiring inthe conduit (see figure 3).

NOTE — Acceptable wiring methods are given in installation documents – e.g., ANSI/NFPA 70 - Article 505.


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17 Rotating electrical machines

External shaft-driven cooling fans of rotating electrical machines shall be enclosed by a fanhood which isnot considered to be part of the enclosure of the electrical apparatus. Such fans and fanhoods shall meetthe following requirements.

17.1 Ventilation openings for external fans

The degree of protection IP of ventilation openings for external fans of rotating electrical machines shall beat least

• IP20 on the air inlet side; and

• IP10 on the air outlet side

according to IEC 60034-5.

For vertical rotating machines, foreign objects shall be prevented from falling into the ventilation openings.For Group I rotating electrical machines the degree of protection IP10 is adequate only when the openingsare designed or arranged so that foreign objects with dimensions above 12.5 mm cannot be carried ontothe moving parts of the machine either by falling vertically or by vibration.

17.2 Construction and mounting of the ventilating systems

Fans, fanhoods, and ventilation screens shall be constructed so as to meet the requirements of theresistance to impact test according to 23.4.3.1 and the required results according to 23.4.3.3.

17.3 Clearances for the ventilating system

In normal operation, the clearances (taking into account design tolerances) between the external fan andits hood, ventilation screens, and their fasteners shall be at least 1/100 of the maximum diameter of thefan, except that the clearances need not exceed 5 mm and may be reduced to 1 mm if the opposing partsare manufactured so as to have dimensional accuracy and stability. In no case shall the clearance be lessthan 1 mm.

17.4 Materials for external fans and fanhoods

17.4.1 Except for fans fitted to Group II rotating electrical machines and having a peripheral speed below50 m/s, external fans, fanhoods, ventilation screens, etc. shall have an electrical insulation resistance,measured according to 23.4.7.8, not exceeding 1 GΩ.

17.4.2 The thermal stability of plastic materials shall be considered adequate if the manufacturer'sspecified operating temperature of the material exceeds the maximum temperature to which the materialwill be subjected in service (within the rating) by at least 20 K.

17.4.3 The external fans, fanhoods, and ventilation screens of rotating electrical machines manufacturedfrom materials containing light metals shall not contain by mass

• for Group I electrical machines, more than 15% in total of aluminum, magnesium and titanium, andmore than 6% in total of magnesium and titanium;

• for Group II electrical machines, more than 6% of magnesium.


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18 Supplementary requirements for switchgear

18.1 Switchgear with contacts immersed in flammable dielectric is not permitted.

18.2 Disconnectors, i.e. disconnecting means, (which are not designed to be operated under the intendedload) shall

• be electrically or mechanically interlocked with a suitable load-breaking device; or

• for Group II apparatus only, be marked at a place near the actuator of the disconnector with thewarning CAUTION — DO NOT OPERATE UNDER LOAD.

18.3 Where switchgear includes a disconnector, the latter shall disconnect all poles and shall be designedso that the position of the disconnector contacts is visible, or their open position is reliably indicated; seeIEC 60947-1 ANSI/UL 508 or ANSI/UL 347, as applicable. Any interlock between such disconnector andthe cover or door of the switchgear shall allow this cover or door to be opened only when the separation ofthe disconnector contacts is effective.

18.4 The operating mechanism of disconnectors for Group I switchgear shall be capable of beingpadlocked in the open position.

18.5 For Group I switchgear provision shall be made to enable short-circuit and earth fault relays, if used,to latch out. If the switchgear has a local resetting device which is accessible from the outside of theenclosure, its access cover shall have a special fastener according to 9.2.

18.6 Doors and covers giving access to the interior of enclosures containing remotely operated circuitswith switching contacts which can be made or broken by non-manual influences (such as electrical,mechanical, magnetic, electro-magnetic, electro-optical, pneumatic, hydraulic, acoustic or thermal) shall

a) either be interlocked with a disconnector which prevents access to the interior unless it has beenoperated to disconnect unprotected internal circuits; or

b) be marked with the warning CAUTION - DO NOT OPEN WHEN ENERGIZED.

In the case of a) above, where it is intended that some internal parts will remain energized after operationof the disconnector, then in order to minimise the risk of explosion, those energized parts shall beprotected by either means below:

c) one of the types of protection listed in clause 1;

d) protection as follows:

• clearances and creepage distances between phases (poles) and to earth in accordance with therequirements of IEC 60079-7 ISA S12.16.01 (IEC 60079-7 Mod); and

• an internal supplementary enclosure which contains the energized parts and provides a degree ofprotection of at least IP30, according to IEC 60529;

• marking on the internal supplementary enclosure with the warning CAUTION - DO NOT OPENWHEN ENERGIZED.


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19 Supplementary requirements for fuses

Enclosures containing fuses shall

• be interlocked so that insertion or removal of replaceable elements can be carried out only with thesupply disconnected and so that the fuses cannot be energized until the enclosure is correctly closed;or

• alternatively the apparatus shall be marked with the warning WARNING - DO NOT OPEN WHENENERGIZED.

20 Supplementary requirements for plugs and sockets

20.1 Plugs and sockets shall

a) either be interlocked mechanically or electrically, or otherwise designed so that they cannot beseparated when the contacts are energized and the contacts cannot be energized when the plug andsocket are separated;

b) or be fixed together by means of special fasteners according to 9.2 and the apparatus marked with thewarning DO NOT SEPARATE WHEN ENERGIZED.

In the case where bolted types cannot be de-energized before separation because they are connected to abattery, the marking shall then state WARNING - SEPARATE ONLY IN A NON-HAZARDOUS AREA.

20.2 Plugs and sockets for rated currents not exceeding 10 A and rated voltage not exceeding either250 V a.c. or 60 V d.c. need not comply with the requirements of 20.1 if all the following conditions arecomplied with:

• the part which remains energized is a socket outlet;

• the plug and socket break the rated current with delayed release to permit the arc to be extinguishedbefore separation;

• the plug and socket remain flameproof to IEC 60079-1 ISA S12.22.01 (IEC 60079-1 Mod) during thearc-quenching period;

• the contacts remaining energized after separation are protected according to one of the specific typesof protection listed in clause 1.

20.3 Plugs and components remaining energized when not engaged with a socket are not permitted.

21 Supplementary requirements for luminaires

21.1 The source of light of luminaires shall be protected by a light-transmitting cover, which may be providedwith an additional guard comprising a mesh of not greater than 50 mm squares. If mesh sizes exceed50 mm squares, then the luminaire cover shall be considered as unguarded.

The light transmitting cover and, if provided, the guard, shall be capable of passing the relevant testsaccording to 23.4.3.1.

The mounting of luminaires shall not depend on a single screw. A single eyebolt may be used only if this isan integral part of the luminaire, for example, by being cast or welded to the enclosure or, if threaded, theeyebolt is locked by a separate means against loosening when twisted.


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21.2 Except in the case of intrinsically safe luminaires to IEC 60079-11 ISA S12.2.01 (IEC 60079-11 Mod),covers giving access to the lampholder and other internal parts of luminaires shall

a) either be interlocked with a device which automatically disconnects all poles of the lampholder as soonas the cover opening procedure begins; or

b) be marked with the warning WARNING - DO NOT OPEN WHEN ENERGIZED.

In the case of a) above, where it is intended that some parts other than the lampholder will remainenergized after operation of the disconnecting device, then in order to minimise the risk of explosion, thoseenergized parts shall be protected by either means as below:

c) one of the specific types of protection listed in clause 1;

d) protection as follows:

• the disconnecting device shall be so arranged that it cannot be operated manually to inadvertentlyenergize unprotected parts; and

• clearances and creepage distances between phases (poles) and to earth in accordance with therequirements of IEC 60079-7 ISA S12.16.01 (IEC 60079-7 Mod); and

• an internal supplementary enclosure (which can be the reflector for the light source) whichcontains the energized parts and provides a degree of protection of at least IP30, according toIEC 60529; and

• marking on the internal supplementary enclosure with the warning CAUTION - DO NOT OPENWHEN ENERGIZED.

21.3 Lamps containing free metallic sodium (for example, low-pressure sodium lamps in accordance withIEC 60192) are not permitted. High-pressure sodium lamps (for example, in accordance with IEC 60662)may be used.

22 Supplementary requirements for caplights, caplamps and handlamps

22.1 Caplights for Group I

The requirements for miners' caplights are under consideration.

22.2 Caplamps for Group II and handlamps

22.2.1 Leakage of the electrolyte shall be prevented in all positions of the apparatus.

NOTE — The materials used for handlamps and caplamps which may be exposed to the electrolyte should be chemically resistant tothe electrolyte.

22.2.2 Where the source of light and the source of supply are housed in separate enclosures, which arenot mechanically connected other than by an electric cable, the cable entries and the connecting cableshall be tested as appropriate according to B.3.1 or B.3.2.


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23 Type verifications and tests

23.1 General

The type verifications and tests are intended to verify that a prototype or sample of the electrical apparatuscomplies with the relevant requirements of this standard and with the relevant requirements of the standardfor the specific type of protection concerned.

23.2 Verification of documents

The testing station shall verify that Documents submitted by the manufacturer shall give a full and correctspecification of the explosion safety aspects of the electrical apparatus.

It shall also verify that In the design of the electrical apparatus, the requirements of this standard and of thespecific standards for the types of protection concerned shall be have been observed.

23.3 Compliance of prototype or sample with documents

The testing station shall verify that The prototype or sample of the electrical apparatus submitted for thetype tests shall comply complies with the manufacturer's documents referred to above.

23.4 Type tests

23.4.1 General

The prototype or sample shall be tested by the testing station in accordance with the requirements for typetests of this standard and of the specific standards for the types of protection concerned. However, thetesting station:

• may omit certain tests judged to be unnecessary. The testing station shall keep a record of all testscarried out and the justification for those omitted;

• shall not make the tests which have already been carried out on an Ex component may be omitted.

The tests shall be made either in the laboratory of the testing station or, subject to agreement between thetesting station and the manufacturer, elsewhere under the supervision of the testing station, for example atthe manufacturer's works.

The testing station, where necessary, shall call for modifications that it considers to be needed to bring theelectrical apparatus into conformity with this standard and with the specific standards for the types ofprotection concerned.

23.4.2 Each test shall be made in that configuration of the apparatus which is considered to be the mostunfavorable by the testing station.

23.4.3 Mechanical tests

23.4.3.1 Test for resistance to impact

In this test the electrical apparatus is submitted to the effect of a test mass of 1 kg falling vertically from aheight h. The height h is dependent on the test mass m and the impact energy E which is specified intable 4 according to the application of the electrical apparatus (h = E / 10 h =E / (10m); h in meters,m in kilograms, and E in joules). The mass shall be fitted with an impact head in hardened steel in theform of a hemisphere of 25 mm diameter.


— 33 —

Before each test, it is necessary to check that the surface of the impact head is in good condition.

Normally the resistance to impact test is made on apparatus which is completely assembled and ready foruse; however, if this is not possible (e.g. for light-transmitting parts) the test is made with the relevant partsremoved but fixed in their mounting or an equivalent frame. Tests on an empty enclosure are permittedonly if there has been prior agreement between the manufacturer and testing station.

For light-transmitting parts made of glass, the test shall be made on three samples but only once on each.In all other cases, the test shall be made on two samples, at two separate places on each sample.

The points of impact shall be the places considered by the testing station to be the weakest. The electricalapparatus shall be mounted on a steel base so that the direction of the impact is normal to the surfacebeing tested if it is flat, or normal to the tangent to the surface at the point of impact if it is not flat. The baseshall have a mass of at least 20 kg or be rigidly fixed or inserted in the floor (secured in concrete forexample). Annex D gives an example of a suitable test rig.

Table 4 — Tests of resistance to impact

When an electrical apparatus is submitted to tests corresponding to the low risk of mechanical danger, itshall be marked with the symbol X according to 27.2 i).

Normally the test is carried out at an ambient temperature of (20 ± 5)°C, except where the material datashows it to have a reduction in resistance to impact at lower temperatures within the specified ambientrange, in which case the test shall be performed at 5 K to 10 K below the lowest temperature within thespecified range.

When the electrical apparatus has an enclosure or a part of an enclosure in plastic material, includingplastic fanhoods and ventilation screens in rotating electrical machines, the test shall be carried out at theupper and lower temperatures according to 23.4.7.1.

23.4.3.2 Drop test

In addition to being submitted to the resistance to impact test according to 23.4.3.1, handheld electricalapparatus or electrical apparatus carried on the person, ready for use, shall be dropped four times from aheight of 1 m onto a horizontal concrete surface. The position of the sample for the drop test shall beselected to represent the position most likely to cause failure of the enclosure. by the testing station.

Impact energyJ

Group I II

Risk of mechanical danger High Low High Low

a) Guards, protective covers, fanhoods, cable entries 20 7 7 4

b) Plastic enclosures 20 7 7 4

c) Light-metal or cast-metal enclosures 20 7 7 4

d) Enclosures of other materials than in c) with wall thickness- less than 3 mm for Group I- less than 1 mm for Group II

20 7 7 4

e) Light-transmitting parts without guard 7 4 4 2

f) Light transmitting parts with guard (tested without guard) 4 2 2 1


— 34 —

For apparatus with an enclosure in other-than-plastic material, the test shall be carried out at atemperature of (20 ± 5)°C, except where the material data shows it to have a reduction in resistance toimpact at lower temperatures within the specified ambient range, in which case the test shall be performedat 5 K to 10 K below the lowest temperature within the specified range.

For electrical apparatus which has enclosures or parts of enclosures made of plastic material, the testsshall be carried out at the lower ambient temperature according to 23.4.7.1.

23.4.3.3 Required results

The resistance to impact and drop tests shall not produce damage invalidating the type of protection of theelectrical apparatus.

Superficial damage, chipping to of paint work, breakage of cooling fins or other similar parts of theelectrical apparatus, and small dents shall be ignored.

External fanhoods and ventilation screens shall resist the tests without displacement or deformationcausing rubbing by the moving parts.

23.4.4 Tests for the degree of protection IP by enclosures

When a Degree of Protection is required by the standard for a specific type of protection, the testprocedures and acceptance criteria shall be in accordance with IEC 60529, except as follows: for rotatingelectrical machines, they shall be in accordance with IEC 60034-5.

Where the manufacturer specifies acceptance criteria more onerous than those described in IEC 60529 orIEC 60034-5 (for example those in a relevant product standard), these shall be applied unless theyadversely affect explosion protection.

Where IEC 60529 is applied, apparatus shall be considered as category 1 as specified in 13.4 of IEC60529.

When tested in accordance with IEC 60529, the apparatus shall not be energized.

When required by IEC 60529, the dielectric test specified in 12.3.2 of IEC 60529 shall be carried out at[(2 Un + 1000) ± 10%] V rms applied between 10 s and 12 s where Un is the maximum rated or internalvoltage of the apparatus.

Where a standard for Electrical Apparatus for Explosive Gas Atmospheres requires acceptance criteria forIPXX, these shall be applied instead of those of IEC 60529 or of IEC 60034-5.

The acceptance criteria in IEC 60034-5 shall be applied to rotating electrical machines, insofar ascompliance with an IEC explosion protection standard is concerned, in addition to their normal operatingconditions.

When enclosures are marked with enclosure-type designations, the tests shall be in accordance withANSI/UL 50, "Enclosures for Electrical Equipment."

23.4.5 Torque test for bushings

Bushings used for connection facilities, and which are subjected to torque during connection ordisconnection of conductors, shall be tested for resistance to torque. Neither the stem in the bushing northe bushing when mounted shall turn when the stem is subjected to a torque of the value given in table 5.


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Table 5 — Torque to be applied to the stem of bushingused for connection facilities

23.4.6 Thermal tests

23.4.6.1 Temperature measurement

The thermal tests shall be made at the rating of the electrical apparatus, with the exception of the thermaltest, to determine the maximum surface temperature. The latter test is performed with the most adverseconditions at the most unfavorable supply voltage between 90% to and 110% of the rated voltage of theelectrical apparatus unless the manufacturer can demonstrate that other international applicable ANSIstandards prescribe other tolerances for equivalent industrial electrical apparatus.

The measured maximum surface temperature shall not exceed:

• for Group I electrical apparatus, those values as given in 5.1.1;

• for Group II electrical apparatus where each manufactured sample is routinely submitted to the thermaltest, the temperature as marked on the electrical apparatus;

• for Group II electrical apparatus, where the electrical apparatus is subjected to type testing, themarked temperature, or the temperature class, less 5 K for temperature classes T6, T5, T4 and T3 andless 10 K for temperature classes T2 and T1.

The result shall be corrected for the maximum ambient temperature specified in the rating.

The measurement of the surface temperatures, temperatures of cable entries and temperatures of otherparts as prescribed in this standard and the specific standards for the types of protection concerned shallbe made in still-ambient air, with the electrical apparatus mounted in its normal service position.

For electrical apparatus which can be normally used in different positions, the temperature in each positionis to be determined, and the highest temperature is to be considered. When the temperature isdetermined for certain positions only, this shall be specified, in the test report and the electrical apparatusshall be marked accordingly either by the symbol X marking or by a label.

Diameter of the stem of the bushingsMetric / (UNF or UNC)

TorqueNm

M 4 (#10) 2.0

M 5 (#12) 3.2

M 6 (1/4) 5

M 8 (5/16) 10

M 10 (7/16) 16

M 12 (1/2) 25

M 16 (5/8) 50

M 20 (7/8) 85

M 24 (1) 130

NOTE — Torque values for sizes other than those specified above may be determined from a graph plotted using thesevalues. In addition, the graph may be extrapolated to allow torque values to be determined for bushings larger than thosespecified.


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The measuring devices (thermometers, thermocouples, etc.) and the connecting cables shall be selectedand so arranged that they do not significantly affect the thermal behavior of the electrical apparatus.

The final temperature is considered to have been reached when the rate of rise of temperature does notexceed 2 K/h.

The testing station shall also determine The temperature of the hottest point of any enclosure, or part ofenclosure, of plastic material (see 7.2) shall be determined.

23.4.6.2 Thermal shock test

Glass parts of luminaires and windows of electrical apparatus shall withstand, without breaking, a thermalshock caused by a jet of water of about 1 mm diameter at a temperature (10 ± 5)°C sprayed on them whenthey are at maximum service temperature.

23.4.7 Tests of non-metallic enclosures or of non-metallic parts of enclosures

23.4.7.1 Ambient temperatures during tests

When, according to this standard or to the specific standards listed in clause 1, tests have to be made as afunction of the permissible upper and lower ambient temperature values, these ambient temperatures shallbe

• for the upper ambient temperature, the maximum ambient temperature in service (see 5.2) increasedby at least 10 K but at most 15 K;

• for the lower ambient temperature, the minimum ambient temperature in service (see 5.2) reduced byat least 5 K but at most 10 K.

23.4.7.2 Tests of enclosures or parts of enclosures in plastic materials

a) Electrical apparatus of Group I

The tests shall be made on six samples as follows:

• two samples shall be submitted to the tests of thermal endurance to heat (see 23.4.7.3), then the testsof thermal endurance to cold (see 23.4.7.4), then the mechanical tests (see 23.4.7.7) and finally to thetests specific to the type of protection concerned.

• two samples shall be submitted to the tests of resistance to oils and greases (see 23.4.7.6) then to themechanical tests (see 23.4.7.7) and finally to the tests specific to the type of protection concerned.

• two samples shall be submitted to the tests of resistance to hydraulic liquids for mining applications(see 23.4.7.6) then to the mechanical tests (see 23.4.7.7) and finally to the tests specific to the type ofprotection concerned.

In the procedures and test sequences described above, the objective is to demonstrate the ability of theplastic material to maintain the specific type of protection listed in clause 1 after exposure to extremes oftemperature and harmful substances likely to be met in use. In an attempt to keep the number of tests to aminimum it is not necessary to perform all of the tests specific to the type of protection on every sample if itis obvious that a sample has not been damaged in such a way as to impair the type of protection offered.Similarly, the number of samples can be reduced if it is possible for the exposure tests and protectionproving tests to be performed in parallel on the same two samples.


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b) Electrical apparatus of Group II

The tests shall be made on two samples which shall be submitted to the tests of thermal endurance to heat(see 23.4.7.3), then to tests of thermal endurance to cold (see 23.4.7.4), then to the mechanical tests (see23.4.7.7), and finally to the tests specific to the type of protection concerned.

23.4.7.3 Thermal endurance to heat

The thermal endurance to heat is determined by submitting the enclosures (or parts of enclosures inplastic materials on which the integrity of the type of protection depends) to continuous storage for fourweeks in an ambience of (90 ± 5)% relative humidity and at a temperature of (20 ± 2) K above themaximum service temperature but at least 80°C.

In the case of a maximum service temperature above 75°C, the period of four weeks specified above willbe replaced by a period of two weeks at (95 ± 2)°C and (90 ± 5)% relative humidity followed by a period oftwo weeks at a temperature of (20 ± 2) K higher than the maximum service temperature.

23.4.7.4 Thermal endurance to cold

The thermal endurance to cold is determined by submitting the enclosures (and parts of enclosures inplastic materials on which the type of protection depends) to storage for 24 h in an ambiencecorresponding to the minimum service temperature reduced according to 23.4.7.1.

23.4.7.5 Resistance to light

23.4.7.5.1 A test of resistance of the material to light shall be made only if the enclosure or parts ofenclosure made of plastic materials are not protected from light. The test is to be conducted as describedbelow unless the material is otherwise evaluated in accordance with the resistance to ultraviolet light testsof ANSI/UL 746C.For electrical apparatus of Group I, the test applies only to luminaires.

The test shall be made on six test bars of standard size 50 mm x 6 mm x 4 mm according to ISO 60179.The test bars are to be made under the same conditions as those used for the manufacture of theenclosure concerned; these conditions are to be stated in the test report of the electrical apparatus.

The test shall be made in accordance with ISO 64892-1 in an exposure chamber using a xenon lamp anda sunlight simulating filter system, at a black panel temperature of (55 ± 3)°C. The exposure time shall be1,000 h.

The evaluation criterion is the impact-bending strength in accordance with ISO 60179. The impact-bending strength following exposure in the case of an impact on the exposed side shall be at least 50% ofthe corresponding value measured on the unexposed test pieces. For materials whose impact-bendingstrength cannot be determined prior to exposure because no rupture has occurred, not more than three ofthe exposed test bars may break.

23.4.7.5.2 If the apparatus is protected from light (for example, daylight or light from luminaires) wheninstalled, and, in consequence, the test of 23.4.7.5.1 is not carried out, the apparatus shall be marked X inaccordance with 27.2 i).

23.4.7.6 Resistance to chemical agents for Group I electrical apparatus

The plastic enclosures and plastic parts of enclosures shall be submitted to tests of resistance to thefollowing chemical agents:

• oils and greases;


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• hydraulic liquids for mining applications.

The relevant tests shall be made on four samples of enclosure sealed against the intrusion of test liquidsinto the interior of the enclosure:

• two samples shall remain for (24 ± 2) h in oil No 2 according to the annex "Test liquids" of ISO 61817,at a temperature of 50°C ±2°C.

• the two other samples shall remain for (24 ± 2) h in fire resistant hydraulic fluid, intended for operatingat temperatures between - 20°C and + 60°C comprising an aqueous solution of polymer in 35% waterat a temperature of 50°C ± 2°C.

At the end of the test, the enclosure samples concerned shall be removed from the liquid bath, carefullywiped and then stored for (24 ± 2) h in the laboratory atmosphere. Subsequently, each of the enclosuresamples shall pass the mechanical tests according to 23.4.7.7.

If one or more of the enclosure samples do not withstand these mechanical tests, special conditions forsafe use shall be stated in the certificate and the marking of the electrical apparatus shall include thesymbol X according to 27.2 i).

23.4.7.7 Mechanical tests

The mechanical tests specified in 23.4.3 shall be carried out on the enclosures and, additionally, in thecase of plastic enclosures, according to 23.4.7.2.

The following detailed conditions shall be observed:

a) Test for resistance to impact

The places of impact shall be on the external parts exposed to impact. If the enclosure of non-metallicmaterial is protected by another enclosure, only the external parts of the assembly shall be subjectedto the resistance to impact tests.

The test shall first be made at the highest temperature, then at the lowest temperature according to23.4.7.1.

b) Drop test

The drop test for electrical apparatus which is held in the hand or carried on the person, shall be madeat the lowest temperatures, according to 23.4.7.1.

23.4.7.8 Insulation resistance test of parts of enclosures of plastic materials

The resistance is tested on the parts of enclosures if size permits, or on a test piece comprising arectangular plate with dimensions in accordance with figure 4, on which two parallel electrodes are paintedon the surface, using a conducting paint with a solvent which has no significant effect on the insulationresistance.

The test piece shall have an intact surface and shall be cleaned with distilled water, then with isopropylalcohol (or any other solvent that can be mixed with water and will not affect the material of the test piece),then once more with distilled water before being dried. Untouched by bare hands, it shall then beconditioned for 24 h at the temperature and humidity according to 7.3. The test shall be carried out underambient conditions.


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The direct voltage applied for 1 min between the electrodes shall be equal to (500 ± 10) V.

During the test, the voltage shall be sufficiently steady so that the charging current due to voltagefluctuation will be negligible compared with the current flowing through the test piece.

The insulation resistance is the quotient of the direct voltage applied at the electrodes to the total currentflowing between them when the voltage has been applied for 1 min.

23.4.8 Tests in explosive mixtures

The standard for the specific type of protection states if tests in explosive mixtures are required andspecifies the explosive mixtures.

NOTE — The purity of commercially available gases and vapors is in general satisfactory for these tests, but if their purity is below95%, they should not be used. The effects of normal variations in the laboratory temperature and of atmospheric pressure, and ofvariations in the humidity of the explosive mixture are acceptable because they have been found to have negligible effect.

24 Routine verifications and tests

The manufacturer shall carry out the routine verifications and tests necessary to ensure that the electricalapparatus produced complies with the specification submitted to the testing station together with theprototype or sample. He shall also make any routine verifications and tests required by the standardslisted in clause 1.

25 Manufacturer's responsibility

By marking the electrical apparatus in accordance with clause 27 the manufacturer attests on his ownresponsibility that:


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• the electrical apparatus has been constructed in accordance with the applicable requirements of therelevant standards in safety matters;

• the routine verifications and tests in clause 24 have been successfully completed and that the productcomplies with the specification submitted to the testing station.

26 Verifications and tests on modified or repaired electrical apparatus

Modifications made on the electrical apparatus affecting the integrity of the type of protection or thetemperature of the apparatus shall be permitted only if the modified apparatus is resubmitted to a testingstation.

For apparatus used in applications other than mines or explosives, modifications and repairs shall be inaccordance with IEC 60079-19.

NOTE — In the case of repairs to electrical apparatus affecting the type of protection, the parts which have been repaired should besubjected to new routine verifications and tests which need not necessarily be made by the manufacturer.

27 Marking

In the interest of safety, it is essential that the system of marking indicated below shall only be applied toelectrical apparatus which complies with the specific standard for the type of protection listed in clause 1.

27.1 The electrical apparatus shall be marked on the main part in a visible place. This marking shall belegible and durable, taking into account possible chemical corrosion.

27.2 The marking shall include:

a) the name of the manufacturer or his registered trade mark;

b) the manufacturer's type identification, e.g. catalog number, part number;

1) Class I

2) The applicable Zone marking i.e., Zone 0 or Zone 1;

c) the symbol AEx, which indicates that the electrical apparatus corresponds to one or more of the typesof protection which are the subject of the specific standards listed in clause 1;

d) the symbol for each type of protection used:

• “o": oil immersion

• “p": pressurization

• "q": powder filling

• "d": flameproof enclosure

• "e": increased safety

• "ia": intrinsic safety, category "ia"

• "ib": intrinsic safety, category "ib"


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• "m": encapsulation.

NOTE — For type "n", see note 1 in clause 1.

Electrical apparatus which does not comply with the requirements of IEC 60079, but is recognized assafe by a national or other appropriate authority shall be marked with the symbol "s",

e) the symbol of the Group of the electrical apparatus:

• I for electrical apparatus for mines susceptible to firedamp;

• II or IIA or IIB or IIC for electrical apparatus for places with a potentially explosive atmosphereother than mines susceptible to firedamp.

The letters A, B, C shall be used if the specific standard for the type of protection concerned specifiesthis.

When the electrical apparatus is certified for use only in a particular gas, the symbol "II" shall befollowed by the chemical formula or name of the gas.

NOTE — Apparatus marked IIB is suitable for applications requiring Group IIA apparatus. Similarly, apparatus marked IIC is suitablefor applications requiring Group IIA and Group IIB apparatus;

f) for Group II electrical apparatus, the symbol indicating the temperature class or the maximum surfacetemperature in °C, or both. When the marking includes both, the temperature class shall be given lastin parentheses. Cable entries need not be marked with the temperature class.

Example: T1 or 350°C or 350°C (T1).

Electrical apparatus for Group II, having a maximum surface temperature greater than 450°C, shallbear only the inscription of the temperature.

Example: 600°C.

Electrical apparatus for Group II, certified and marked for use in a particular gas, need not have atemperature reference.

Where appropriate according to 5.2 the marking shall include either the symbol Ta or Tamb togetherwith the special range of ambient temperature or the symbol X;

g) a serial number, except for

• connection accessories (cable and conduit entries, blanking plates, adaptor plates, plugs andsockets and bushings);

• very small electrical apparatus on which there is limited space.

(The batch number can be considered to be an alternative to the serial number.);

h) where a certificate has been issued, the name or mark of the testing station and the certificatereference in the following form: the last two figures of the year of certification followed by the serialnumber of the certificate in that year;


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i) specific installation instructions or reference to a specific installation document when If the testingstation considers that it is necessary to indicate special conditions for safe use.the symbol X shall beplaced after the certificate reference. The testing station may accept the use of a warning marking asan alternative to the requirement for the X marking.

NOTE — The manufacturer should ensure that the requirements of the special conditions for safe use are passed to the purchasertogether with any relevant information;

j) any additional marking prescribed in the specific standards for the types of protection concerned, as inclause 1; and

k) any marking normally required by the standards for construction of the electrical apparatus. Thismarking need not be verified by the testing station.

27.3 Where different types of protection are used on different parts of an electrical apparatus, eachrespective part shall bear the symbol for the type of protection concerned.

Where more than one type of protection is used in an electrical apparatus, the symbol for the main type ofprotection shall appear first and be followed by the symbols the other types of protection used.

27.4 The markings c) to f) according to 27.2 shall be placed in the order in which they are given above.

27.5 Ex components, according to clause 13, shall be marked in a visible place. This marking shall belegible and durable and shall include:

a) the name or the registered trade mark of the manufacturer;

b) the manufacturer's type identification;

c) the symbol AEx;

d) the symbol for each type of protection used;

e) the symbol of the Group of the Ex component;

f) the name or mark of the testing station;

g) the certificate reference followed by the symbol "U" (the symbol "X" shall not be used);

h) the additional marking prescribed in the specific standard for the types of protection concerned as inclause 1; and

i) the marking normally required by the standards for construction of the Ex component. This markingneed not be verified by the testing station.

27.6 On very small electrical apparatus and on Ex components where there is limited space, the testingstation may allow a reduction in the marking may be allowed, but at least the following will be required onthe apparatus or on the smallest unit package but will require at least:

a) the name or registered trade mark of the manufacturer;

b) the symbol AEx and the symbol of the type of protection;

c) the name or mark of the testing station;


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d) the certificate reference; and

e) the installation reference per 27.2 i); for electrical apparatus, the symbol X if appropriate; or for Excomponents, the symbol U.

f) Cl I;

g) Zn 0, Zn 1, or Zn 2; as appropriate;

h) II, IIA, IIB, IIC, or chemical formula; as appropriate;

i) the symbol indicating the temperature class or the maximum surface temperature in °C, or both. Whenthe marking includes both, the temperature class shall be given last in parentheses.

The markings of h) and i) shall follow those of b).

27.7 Examples of marking of certified apparatus

NOTE — These examples do not include the marking normally required by the standards for construction of the electrical apparatus;see 27.2 k) and 27.5 i).

27.7.1 Flameproof electrical apparatus for use in mines susceptible to firedamp.

BEDELLE S.AType A B 5Ex d INo. 325HSE (M) 92.5.2209..................................

27.7.2 Ex Component, partly flameproof and partly intrinsically safe, for places in potentially explosiveatmospheres other than in mines susceptible to firedamp, gas of subdivision C, manufactured by H.RIDSTONE and Co, Ltd.

RIDSTONE and Co, LtdType KW 369Class I, Zone 1, AEx d ia IICDEMKO 92. 536 U................................

27.7.3 Electrical apparatus, partly increased safety and partly with pressurized enclosure, maximumsurface temperature of 125°C, for places in potentially explosive atmospheres other than minessusceptible to firedamp, with gas of ignition temperature greater than 125°C. and with special conditions forsafe use indicated in the certificate.

H. ATHERINGTONYPE 250 JG 1Class I, Zone 1, AEx ep II 125ºC (T4)No. 56732L.C.I.E. 92.076 X..................................


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27.7.4 Electrical apparatus, partly flameproof and partly increased safety for use in mines susceptible tofiredamp and places in potentially explosive atmospheres other than mines susceptible to firedamp withgas of subdivision B and ignition temperature greater than 200EC.

A.R. ACHUTZ A.G.TYPE 5 CDEx de I/IIB T3No. 5634BVS Nr 92.521..........................

27.7.5 Flameproof electrical apparatus for places in potentially explosive atmospheres other than minessusceptible to firedamp on the basis of ammonia gas only.

WOKAITERT SARLTYPE NT 3Class I, Zone 1, AEx d II (NH3)No. 6549INIEX-NIEB 92.3102....................................

27.8 Where cautionary markings are required on the apparatus, the text as described, following the word“CAUTION” or “WARNING,” may be replaced by technically equivalent text.

NOTE — The preferred format of cautionary markings includes three elements: a key word such as WARNING or CAUTION, thehazard risk, and the action required to avoid the hazard.

27.9 Threaded holes that are not threaded NPT or provided with adapters to NPT and are intended for theinstallation of conduit or cable entries shall be identified to indicate the thread form.


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Annex A (informative) — Subdivision of gases and vapours according to theirmaximum experimental safe gaps and minimum ignition currents

NOTE— Additional information on the classification of gases and vapors may be found in ANSI/NFPA 497, “Classification of FlammableLiquids, Gases or Vapors and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas” or ANSI/APIRP505, “Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I,Zone 0, Zone 1, and Zone 2.”

Flammable liquids, gases, and vapors are grouped by ANSI/NFPA 70, the National Electrical Code©,according to the following:

• Group IIC - Atmospheres containing acetylene, hydrogen, or flammable gas, flammable liquid-produced vapor, or combustible liquid-produced vapor mixed with air that may burn or explode, havingeither a maximum experimental safe gap (MESG) value less than or equal to 0.50 mm or a minimumigniting-current ratio (MIC ratio) less than 0.45.

• Group IIB - Atmospheres containing acetaldehyde, ethylene, or flammable gas, flammable liquid-produced vapor, or combustible liquid-produced vapor mixed with air that may burn or explode havingeither a maximum experimental safe gap (MESG) value greater than 0.50 mm and less than or equalto 0.90 mm or a minimum igniting current ratio (MIC ratio) greater than 0.45 and less than or equal to0.80.

• Group IIA - Atmospheres containing acetone, ammonia, ethyl alcohol, gasoline, methane, propane, orflammable gas, flammable liquid-produced vapor, or combustible liquid-produced vapor mixed with airthat may burn or explode having either a maximum experimental safe gap (MESG) value greater than0.90 mm or a minimum igniting current ratio (MIC ratio) greater than 0.80.

For flameproof enclosures of electrical apparatus, gases and vapours are subdivided according to theirmaximum experimental safe gaps (MESG) determined by means of an experimental vessel having a widthof joint of 25 mm. The standard method of determining the MESG shall be with the vessel described inIEC 60079-1A, but if the determinations have been made only with an 8 litre sphere with ignition close tothe joint, these can be accepted provisionally.

The limits are:

• subdivision A: MESG above 0.9 mm;

• subdivision B: MESG between 0.5 mm and 0.9 mm;

• subdivision C: MESG below 0.5 mm.

For intrinsically safe electrical apparatus, gases and vapours are subdivided according to the ratio of theirminimum igniting currents (MIC) to that of laboratory methane. The standard method of determining thisratio shall be with the apparatus described in IEC 60079-3, but if these determinations have been madeonly with other apparatus, these can be accepted provisionally.

The limits are:

• subdivision A: MIC ratio above 0.8;

• subdivision B: MIC ratio between 0.45 and 0.8;

• subdivision C: MIC ratio below 0.45.


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For most gases and vapours it is sufficient to make only one of these determinations (either MESG or MICratio) to place the gas or vapour in the appropriate subdivision. A single determination is sufficient in thefollowing cases:

• subdivision A: when the MESG exceeds 0.9 mm or otherwise the MIC ratio exceeds 0.9;

• subdivision B: when the MESG is between 0.55 mm and 0.9 mm or otherwise the MIC ratio is between0.5 and 0.8;

• subdivision C: when the MESG is less than 0.5 mm or otherwise the MIC ratio is less than 0.45.

It is necessary to do the determination of both the MESG and MIC ratio in the following cases:

1) Only the MIC ratio has been determined and its value is between 0.8 and 0.9: the determination of theMESG is necessary to determine the subdivision.

2) Only the MIC ratio has been determined and its value is between 0.45 and the determination of theMESG is necessary to determine the subdivision.

3) Only the MESG has been determined and its value is between 0.5 mm and 0.55 mm: thedetermination of the MIC ratio is necessary to determine the subdivision.

When a gas or vapour belongs to a homologous series of compounds, the appropriate subdivision of thegas or vapour can provisionally be inferred from the results of the determinations of other compounds ofthe series with lower molecular weights.

These general principles have been used to draw up the following lists of gases and vapours.

The letters against each gas or vapour denote:

a) subdivision according to the MESG value;

b) subdivision according to the value of the MIC ratio;

c) where both MESG and MIC ratio have been determined;

d) subdivision according to similarity of chemical structure (provisional subdivision).

NOTE 1 — Industrial methane includes methane mixtures containing up to 15% by volume of hydrogen.

NOTE 2 — Carbon monoxide may include a moisture content sufficient to saturate a carbon monoxide-air mixture at normal ambienttemperature.

NOTE 3 — IEC 60079-20 provides additional data for gases and vapors.

Gases not included in this list may be categorized according to their MIC ratio and MESG, but care shouldbe taken to identify any unusual performance (e.g. a gas may have MIC and MESG figures which wouldpermit IIC categorisation, but its explosion pressure may exceed that of hydrogen and acetylene, whichprecludes such categorisation).


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Table A.1 — Subdivision A

1 Hydrocarbons

Alkanes:

methane CH4 c

ethane C2H6 c

propane C3H8 c

butane C4H10 c

pentane C5H12 c

hexane C6H14 c

heptane C7H16 c

octane C8H18 a

nonane C9H20 d

decane C10H22 a

cyclopropane CH2CH2CH2 a

cyclobutane CH2(CH2)2CH2 d

cyclopentane CH2(CH2)3CH2 a

cyclohexane CH2(CH2)4CH2 c

cycloheptane CH2(CH2)5CH2 d

methylcyclobutane CH3CH(CH2)2CH2 d

methylcyclopentane CH3CH(CH2)3CH2 d

methylcyclohexane CH3CH(CH2)4CH2 d

ethycyclobutane C2H5CH(CH2)2CH2 d

ethylcyclopentane C2H5CH(CH2)3CH2 d

ethylcyclohexane C2H5CH(CH2)4CH2 d

decahydronaphthalene (dekalin) CH2(CH2)3CH CH(CH2)3CH2 d

Alkenes:

propene (propylene) CH3CH = CH2 a

Aromatic hydrocarbons:

styrene C6H5CH = CH2 b

Benzenoids:

benzene C6H6 c

toluene C6H5CH3 d

xylene C6H4(CH3)2 a

ethylbenzene C6H5C2H5 d

trimethylbenzene C6H5(CH3)3 d

naphthalene C10H8 d

cumene C6H5CH(CH3)2 d

cymene (CH3)2CH C6H4CH3 d

Mixed Hydrocarbons:

methane (industrial) See note 1 a (calculated)

turpentine d

petroleum naphtha d

coal tar naphtha d

petroleum (including motor spirit) d

solvent or cleaning petroleum d

heating oil d

kerosene d

diesel oil d

motor benzole a


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Table A.1 — Subdivision A (cont'd)

2 Compounds containing oxygen

Alcohols and phenols:

methanol CH3OH c

ethanol C2H5OH c

propane-2-ol C3H7OH a

butanol C4H9OH a

pentanol C5H11OH a

hexanol C6H13OH a

heptanol C7H15OH d

octanol C8H17OH d

nonanol C9H19OH d

cyclohexanol CH2(CH2)4CH OH d

methylcyclohexanol CH3CH(CH2)4CH OH d

phenol C6H5OH d

cresol CH3C6H4OH d

4-hydroxy-4 methylpentan-2-one (diacetone alcohol) (CH3)2C(OH)CH2COCH3 d

Aldehydes:

acetaldehyde CH3CHO a

metaldehyde (CH3CHO)n d

Ketones:

cyclohexanol CH2(CH2)4CH OH d

acetone (CH3)2CO c

pentan-2-one (propyl methyl ketone) C3H7CO CH3 a

hexan-2-one (butyl methyl ketone) C4H9CO CH3 a

amyl methyl ketone C5H11CO CH3 d

pentane-2, 4-dione (acetylacetone) CH3CO CH2CO CH3 a

cyclohexanone CH2(CH2)4CO a

Esters:

methyl formate H COO CH3 a

ethyl formate HCOO C2H5 a

methyl acetate CH3COO CH3 c

ethyl acetate CH3COO C2H5 a

propyl acetate CH3COO C3H7 a

butyl acetate CH3COO C4H9 c

amyl acetate CH3COO C5H11 d

methyl methacrylate CH2 = CCH3COOCH3 a

ethyl methacrylate CH2 = CCH3COOC2H5 d

vinyl acetate CH3COOCH = CH2 a

ethyl acetoacetate CH3COCH2COOC2H5 a

Acids:

acetic acid CH3COOH b

3 Compounds containing halogens

Compounds without oxygen :

Chloromethane CH3Cl a

chloroethane C2H5Cl b

bromethane C2H5Br d


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Table A.1 — Subdivision A (cont'd)

chloropropane C3H7Cl a

chlorobutane C4H9Cl a

bromobutane C4H9Br d

dichloroethane C2H4Cl2 a

dichloropropane C3H6Cl2 d

chlorobenzene C6H5Cl d

benzyle chloride C6H5CH2Cl d

dichlorobenzene C6H4Cl2 d

allyl chloride CH2 = CHCH2Cl b

dichloroethylene CHC1 = CH Cl a

chloroethylene (vinyl chloride) CH2 = CH Cl c

d.d.d-trifluorotoluene (benzotrifluoride) C6H5CF3 a

dichloromethane (methylene chloride) CH2Cl2 d

Compounds with oxygen :

acetyl chloride CH3COCl d

chloroethanol CH2ClCH2OH d

4 Compounds containing sulphur

ethanethiol (ethylmercaptan) C2H5SH c

propane-1-thiol (propylmercaptan) C3H7SH a (calculated)

thiophene CH = CH CH = CH S a

tetrahydrothiophene CH2(CH2)2CH2S a

5 Compounds containing nitrogen

ammonia NH3 a

acetonitrile CH3CN a

nitromethane CH3NO2 d

nitroethane C2H5NO2 d

Amines :

methylamine CH3NH2 a

dimethylamine (CH3)2NH a

trimethylamine (CH3)3N a

diethylamine (C2H5)2NH d

triethylamine (C2H5)3N d

propylamine C3H7NH2 d

butylamine C4H9NH2 c

cyclohexylamine CH2(CH2)4CH NH2 d

2-aminoethanol (ethanolamine) NH2 CH2 CH2OH d

2-diethylaminoethanol (C2H5)2NCH2CH2OH d

diaminoethane NH2CH2CH2NH2 a

aniline C6H5NH2 d

NN-dimethylanaline C6H5N(CH3)2 d

amphetamine C6H5CH2CH(NH2)CH3 d

toluidine CH3C6H4NH2 d

pyridine C5H5N d


— 50 —

Table A.2 — Subdivision B

Table A.3 — Subdivision C

1 Hydrocarbons

propyne (allylene, methylacetylene) CH3C CH b

ethylene C2H4 c

1,3-butadiene CH2 = CH CH = CH2 c

isopropenylbenzene (methyl styrene) C6H5C(CH3) = CH2 a

2 Compounds containing nitrogen

acrylonitrile CH2 = CHCN c

isopropyl nitrate (CH3)2CHONO2 b

hydrogen cyanide HCN a

nitroethane C2H5NO2 a

3 Compounds containing oxygen

carbon monoxide CO (see Note 2) a

dimethyl ether (CH3)2O c

ethyl methyl ether CH3OC2H5 d

diethyl ether (C2H5)2O c

dipropyl ether (C3H7)2O

dibutyl ether (C4H9)2O c

ethylene oxide (oxione) CH2CH2O c

1,2-epoxypropane (propylene oxide) CH3CHCH2O c

propan-1-ol C3H7OH a

butanone (ethyl methyl ketone) C2H5COCH3 a

1,3-dioxolane CH2CH2OCH2O d

1,4-dioxane CH2CH2OCH2CH2O a

1,3,5-trioxane CH2OCH2OCH2O b

butyl glycolate (hydroxyacetic acid, butyl ester) HOCH2COOC4H9 a

tetrahydrofurfuryl alcohol CH2CH2CH2O CH CH2OH d

methyl acrylate CH2 = CHCOOCH3 a

ethyl acrylate CH2 = CHCOOC2H5 a

furan CH = CHCH = CHO a

crotonaldehyde CH3CH = CHCNO a

acrylaldehyde (acrolein) CH2 = CHCHO a (calculated)

tetrahydrofuran CH2(CH2)2CH2O a

4 Mixtures

coke oven gas d

5 Compounds containing halogens

tetrafluoroethylene C2F4 a

1-chloro- 2.3-epoxypropane (epichlorohydrin) OCH2CHCH2Cl a

6 Compounds containing sulphur

ethanethiol (ethylmercaptan) C2H5SH a

hydrogen H2 c

acetylene C2H2 c

carbon disulphide CS2 c


— 51 —

Annex B (normative) — Ex cable entries (glands or fittings)

NOTE — This annex may not be suitable for some of the wiring practices currently permitted by the NEC. The ordinary locationrequirements of ANSI/UL 514B normally apply to all NEC wiring methods. Requirements contained in this annex, such as tensile,mechanical, impact, and ingress protection, supplement the requirements of ANSI/UL 514B and also those requirements for types ofprotection ‘d’ and ‘e’.

B.1 General

This annex specifies the general requirements for the construction, testing and marking of Ex cable entriesand may be supplemented or modified by the standards listed in clause 1.

NOTE — The minimum diameter of cable for which the entry is suitable is specified by the manufacturer. The user should ensurethat, taking tolerances into account, the minimum dimensions of the cable selected for use in the cable entry (gland or fitting) areequal to or exceed these specified values.

B.2 Constructional requirements

B.2.1 Cable sealing

The cable sealing between the cable and the entry body shall be ensured by one of the following means(see figure B.1):

• an elastomeric sealing ring;

• a metallic or composite sealing ring;

• a filling compound.

The cable sealing may be made of a single material or a combination of materials and shall be appropriateto the shape of the cable concerned.

NOTE 1 — In selecting the materials for metallic or composite sealing rings, attention is drawn to the note of 6.1.

NOTE 2 — The type of protection of the enclosure may also depend on the internal construction of the cable.


— 52 —

B.2.2 Materials

B.2.2.1 The requirements relating to materials in 7.3, concerning electrostatic charges, apply only toexposed parts of cable entries.

B.2.2.2 Elastomeric sealing rings shall be made of materials that satisfy the type test for resistance ofaging as defined in B.3.3.

B.2.2.3 Materials used as filling compounds shall comply with the requirements of clause 12 for materialsused for cementing.

B.2.3 Clamping

B.2.3.1 Cable entries shall provide clamping of the cable in order to prevent pulling or twisting applied toit from being transmitted to the connections. Such clamping can be provided by a clamping device, sealingring, or filling compound. Whichever clamping arrangement is used, it shall be capable of meeting therelevant type tests in B.3. In the case of unarmored cable, this function may also be ensured either by thesealing ring or by the filling compound.

B.2.3.2 Group II cable entries without a clamping device may also be accepted as complying with thisannex if they are capable of passing the clamping tests with values reduced to 25% of those required in B.3when the descriptive documents shall then state that such cable entries may be used only for fixed


— 53 —

installations of Group II and that the user shall ensure adequate clamping of the cable. Such cable entriesshall be marked with the symbol X.

B.2.4 Lead-in of cable

B.2.4.1 Cable entries shall not have sharp edges capable of damaging the cable.

B.2.4.2 In the case of flexible cables, the point of entry shall include a rounded edge at an angle of at least75°, the radius R of which is at least equal to one quarter of the diameter of the maximum admissible cablein the entry but which need not exceed 3 mm (see figure B.2).

B.2.5 Cable entries shall be designed so that after installation, they can only be released or dismantledby means of a tool.

B.2.6 The means of fixing cable entries to enclosures of electrical apparatus shall be capable of retainingthe cable entry when subjected to the mechanical tests of clamping and resistance to impact in B.3.

B.2.7 Cable entries shall be capable of providing, with the enclosure on which they are fixed, the samedegree of protection as required for the enclosure. The test method is specified in B.3.5.

B.3 Type tests

B.3.1 Tests of clamping of non-armored and braided cables

B.3.1.1 Cable entries with clamping by the sealing ring

The tests of clamping shall be carried out using for each type of cable entry, two sealing rings; one equal tothe smallest admissible size and the other equal to the greatest admissible size.


— 54 —

In the case of elastomeric sealing rings for circular cables, each ring is mounted on a clean, dry, polished,cylindrical, mild, steel mandrel equal to the smallest cable diameter allowable in the ring and specified bythe manufacturer of the cable entry.

For non-circular cables, the ring shall be mounted on a sample of dry, clean cable of dimensions equal tothe size specified by the manufacturer of the cable entry.

In the case of metallic sealing rings, each ring is mounted on a sample of clean, dry cable of a diameterequal to the smallest diameter allowable in the ring and specified by the manufacturer of the cable entry.

The sealing ring with the mandrel or the cable, according to the case, is fitted into the cable entry. A torqueis then applied to the screws (in the case of a flanged compression element fitted with screws) or to the nut(in the case of a screwed compression element) in order to obtain the compression of the sealing ring andprevent slipping of the mandrel or cable when the force applied to it is the value in newtons equal to

• 20 times the value in millimeters of the diameter of the mandrel or cable when the cable entry isdesigned for round cable; or

• 6 times the value in millimeters of the perimeter of the cable when the cable entry is designed for non-circular cable.

For test conditions and acceptance criteria, see B.3.1.4.

NOTE — The torque figures referred to above may be determined experimentally prior to the tests, or they may be supplied by themanufacturer of the cable entry.

B.3.1.2 Cable entries with clamping by filling compound

The tests of clamping shall be carried out using two samples of clean, dry cable — one equal to thesmallest admissible size and the other equal to the largest admissible size.

The filling compound, prepared as stated by the manufacturer of the cable entry, is filled into the availablespace, and the entry is submitted to the tests after the compound has hardened in accordance with themanufacturer's instructions.

The filling compound shall prevent slippage of the cable when the force applied to it is the value in newtonsequal to

• 20 times the value in millimeters of the diameter of the cable sample when the cable entry is designedfor circular cable; or

• 6 times the value in millimeters of the perimeter of the cable sample when the cable entry is designedfor non-circular cable.

For test conditions and acceptance criteria, see B.3.1.4.

B.3.1.3 Cable entries with clamping by means of a clamping device

The test of clamping shall be carried out using for each type of cable entry, clamping devices of thedifferent allowable sizes.

Each device is mounted on a sample of clean, dry cable of a diameter allowable in the device and specifiedby the manufacturer of the cable entry. For non-circular cables, the ring shall be mounted on the sheath ofa sample of dry cable of dimensions equal to the size specified for use with the sealing ring.


— 55 —

The clamping device with the cable and the sealing ring whose size is equal to the largest size of cableallowable in that ring and specified by the manufacturer of the cable entry, are then fitted in the cable entry;the entry is then assembled with compression of the sealing ring and tightening of the clamping device.The test procedure shall be carried out according to B.3.1.1.

B.3.1.4 Tensile test

The prepared sample is mounted on a tensile testing machine, and a constant tensile force equal to thatdefined above is then applied for 6 h. The test is carried out at an ambient temperature of (20 ± 5)°C.

The clamping assured by the sealing ring, filling compound, or by the clamping device is acceptable if theslippage of the mandrel or cable sample is not more than 6 mm.

B.3.1.5 Mechanical strength

After the tensile test, the cable entry is removed from the tensile-testing machine and submitted to thefollowing tests and examinations as appropriate.

B.3.1.5.1 In the case of cable entries with clamping by sealing ring or a clamping device, a mechanicalstrength test on which a torque of 1.5 times the value needed to prevent slipping is applied to the screws ornuts, whichever is the case. The cable entry is then dismantled and the components examined. Themechanical strength of the cable entry is acceptable if no deformation affecting the type of protection isfound. Any deformation of the sealing rings shall be ignored.

Where cable entries are manufactured from plastic material, if the prescribed proof torque cannot be metdue to temporary deformations of the thread, and no noticeable damage is found, the cable entry shall bedeemed to have passed the test.

B.3.1.5.2 In the case of cable entries with clamping by filling compound, the gland is dismantled as far aspossible without damaging the filling compound. Upon examination there shall be no physical or visibledamage to the filling compound that would affect the type of protection afforded.

B.3.2 Tests of clamping of armored cables

B.3.2.1 Tests of clamping where the armorings are clamped by a device within the gland

B.3.2.1.1 The tests shall be carried out using, for each size of entry, a sample of armored cable of thesmallest size specified.

The sample of armored cable is fitted into the clamping device of the cable entry. A torque is then appliedto the screws (in the case of a flanged clamping device) or to the nut (in the case of a screwed clampingdevice) in order to compress the clamping device and to prevent slipping of the armor when the forceapplied to it equals a value in newtons equal to 20 times the value in millimeters of the diameter of thecable over the armor for Group II.

• 80 times the value in millimeters of the diameter of the cable over the armor for Group I; or

NOTE — The torque values referred to in the preceding paragraph may be determined experimentally prior to the tests, or they maybe supplied by the manufacturer of the cable entry.


— 56 —

B.3.2.1.2 Tensile test

The prepared sample is mounted on a tensile testing machine, and a constant tensile force equal to thatdefined above is then applied for (120 ± 10) s. The test is carried out at an ambient temperature of(20 ± 5)°C.

The clamping assured by the clamping device is acceptable if the slipping of the armor is effectively zero.

B.3.2.1.3 Mechanical strength

Where screws and nuts are fitted, they shall be tightened to 1.5 times the values in B.3.2.1.1 and then thecable entry dismantled. The mechanical strength is acceptable if no deformation affecting the type ofprotection is found.

B.3.2.2 Tests of clamping where the armorings are not clamped by a device within the gland

The cable entry shall be treated as if it is non-armored type according to B.3.1.

B.3.3 Aging test for material used for elastomeric sealing rings

The material used for the manufacture of the sealing rings is prepared in the form of test pieces inaccordance with the standards ISO 48 and ISO 1818; the hardness is determined in accordance with thesame standards at ambient temperature.

The test piece is then placed in an oven in which the temperature is maintained at (100 ± 5)°C for at least168 h without interruption; they are then kept for at least 24 h at ambient temperature, then placed in arefrigerator in which the temperature is maintained at (-20 ± 2)°C for at least 48 h without interruption; theyare finally kept for at least 24 h at ambient temperature. The hardness is then determined again.

At the end of the test procedure, the variation in hardness, expressed in IRHD units as specified in the ISOstandards given above, shall not exceed 20% of the hardness before aging.

Where a cable entry is intended to be used at a temperature above that foreseen in 16.8, the aging testshall be carried out at a temperature (20 ± 5) K above the declared maximum operating temperature of thecable. Where a cable entry is intended to be used in an ambient temperature below -20°C, the test in therefrigerator shall be carried out at the declared minimum ambient temperature with a tolerance of ± 2 K.

B.3.4 Type test for resistance to impact

The test shall be carried out by applying the appropriate requirements according to 23.4.3. The cableentry shall be tested with the smallest specified cable fitted.

For testing purposes, the cable entry is fixed on a rigidly mounted steel plate or secured as specified by themanufacturer of the cable entry. The torque applied in fixing the threaded cable entry shall be according toB.3.1.5 or B.3.2.1.1 as appropriate.

B.3.5 Type test for degree of protection (IP) of cable entries

The test shall be carried out following the conditions given in IEC 60529, using for each type of cable entry,one cable sealing ring of each of the different permitted sizes.

For sealing tests, each sealing ring is mounted on a sample of clean, dry cable of a diameter equal to thesmallest diameter allowable in the ring as specified by the manufacturer of the cable entry. The cable entrywith cable is tested after being fixed to a sealed enclosure.


— 57 —

B.4 Marking

B.4.1 Marking of cable entries

Cable entries shall be marked in accordance with 27.2 and, if a threaded entry, with the type and size ofthread.

Where marking space is limited, the reduced marking requirements of 27.6 may be applied.

B.4.2 Marking of cable-sealing rings

The cable-sealing rings of cable entries, allowing a series of rings, shall bear the indications of theminimum and maximum diameters, expressed in millimeters, of the permitted cables.

When the cable-sealing ring is bound with a metal washer, the marking may be made on the washer.

The cable sealing rings shall carry an identifying marking, allowing the user to determine if the ring isappropriate for the cable entry.

Where the entry and the ring are intended to be used at temperatures outside the range -20°C to +80°Cand have been tested accordingly, as specified in B.3.3, they shall be marked with the temperature range.


— 59 —

Annex C (normative) — Ex components

Table C.1 — Clauses with which Ex components shall comply

Clauses of this standard Applies(yes or no) Remarks

1 to 4 (inclusive) yes except 4.2.2

5 noexcept that the operating temperature limits shall be

specified

6.1 yes

6.2 no

7.1 yes

7.2 yes*consideration to be given to the circumstances in whichthese requirements apply to components placed in other

enclosures.

7.3 yes if external (* ditto)

7.4 yes if external (* ditto)

8 yes

9.1 yes

9.2 yes but only if it is an apparatus enclosure


10 yes

11 yes

12 yes

13 yes

14 yes except no X marking is necessary



15.3 yes

15.4 yes

15.5 yes

16 yes but only if it is an apparatus enclosure

17 no except for machine enclosures

18 yes

19 yes

20 yes

21 yes

22.1 yes

23.1 yes

23.2 yes

23.3 yes

23.4.1 yes

23.4.2 no

23.4.3 yes but only if it is an apparatus enclosure23.4.4 yes but only if it is an apparatus enclosure

23.4.5 yes

23.4.6.1 no


— 60 —

Table C.1 — Clauses with which Ex components shall comply (cont'd)

23.4.6.2 yes where the maximum temperature is specified

23.4.7 yes where the maximum temperature is specified

23.4.8 yes

24 yes

25 yes

26 yes

271) yes

27.1 no

27.2 no

27.3 no

27.4 no

27.5 yes

27.6 yes

27.7 yes1) The Temperature Classification is not applied to Ex components.


— 61 —

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


— 63 —

Annex E (informative) — Common standards -safety requirements for electrical equipiment

The following are common standards used to verify conformance with safety requirements for electricalequipment. This list is not comprehensive.

ANSI/ISA S82.01 Electrical and Electronic Test, Measuring, Controlling, and RelatedEquipment – General Requirements

ANSI/ISA S82.03 Electrical and Electronic Test, Measuring, Controlling, and RelatedEquipment – Electrical and Electronic Process Measurement and ControlEquipment

ANSI/UL 20 General-Use Snap Switches

ANSI/UL 50 Enclosures for Electrical Equipment

ANSI/UL 67 Panelboards

ANSI/UL 94 Tests for Flammability of Plastic Materials for Parts in Devices and Appliances

ANSI/UL 153 Portable Electric Lamps

ANSI/UL 298 Portable Electric Hand Lamps

ANSI/UL 347 High Voltage Industrial Control Equipment

ANSI/UL 427 Refrigerating Units

ANSI/UL 429 Electrically Operated Valves

ANSI/UL 464 Audible Signal Appliances

ANSI/UL 486A Wire Connectors and Soldering Lugs for Use with Copper Conductors

ANSI/UL 486B Wire Connectors for Use with Aluminum Conductors

ANSI/UL 486C Splicing Wire Connectors

ANSI/UL 486E Equipment Wiring Terminals for Use with Aluminum and/or Copper A Conductors

ANSI/UL 489 Molded-Case Circuit Breakers and Circuit-Breaker Enclosures

ANSI/UL 498 Attachment Plugs and Receptacles

ANSI/UL 508 Industrial Control Equipment

ANSI/UL 512 Fuseholders

ANSI/UL 514A Metallic Outlet Boxes

ANSI/UL 514B Fittings for Conduit and Outlet Boxes


— 64 —

ANSI/UL 514C Nonmetallic Outlet Boxes, Flush-Device Boxes, and Covers

ANSI/UL 595 Marine-Type Electric Lighting Fixtures

ANSI/UL 746A Polymeric Materials – Short Term Property Evaluations

ANSI/UL 746B Polymeric Materials – Long Term Property Evaluations

ANSI/UL 746C Polymeric Materials – Use in Electrical Equipment Evaluations

ANSI/UL 746D Polymeric Materials – Fabricated Parts

ANSI/UL 746E Polymeric Materials – Industrial Laminates, Filament Wound Tubing

ANSI/UL 840 Insulation Coordination Including Clearances and Creepage Distances forElectrical Equipment

ANSI/UL 864 Control Units for Fire Protective Signaling Systems

ANSI/UL 873 Temperature-Indicating and -Regulating Equipment

ANSI/UL 924 Emergency Lighting and Power Equipment

ANSI/UL 943 Ground-Fault Circuit-Interrupters

ANSI/UL 984 Hermetic Refrigerant Motor-Compressors

ANSI/UL 1004 Electric Motors

ANSI/UL 1053 Ground-Fault Sensing and Relaying Equipment

ANSI/UL 1059 Terminal Blocks

ANSI/UL 1097 Double Insulation Systems for Use in Electrical Equipment

UL 1104 Marine Navigation Lights

ANSI/UL 1480 Speakers for Fire Protective Signaling Systems

ANSI/UL 1481 Power Supplies for Fire Protective Signaling Systems

UL 1562 Transformers, Distribution, Dry-Type – Over 600 Volts

ANSI/UL 1570 Fluorescent Lighting Fixtures

ANSI/UL 1571 Incandescent Lighting Fixtures

ANSI/UL 1572 High Intensity Discharge Lighting Fixtures

ANSI/UL 1585 Class 2 and Class 3 Transformers

ANSI/UL 1638 Visual Signaling Appliances – Private Mode Emergency and General UtilitySignaling


— 65 —

UL 1682 Plugs, Receptacles, and Cable Connectors of the Pin and Sleeve Type

ANSI/UL 1740 Industrial Robots and Robotic Equipment

ANSI/UL 1950 Safety of Information Technology Equipment, Including ElectricalBusinessEquipment (Second Edition)

ANSI/UL 1971 Signaling Devices for the Hearing Impaired

UL 2111 Overheating Protection for Motors

UL 2225 Metal-Clad Cables and Cable-Sealing Fittings for Use in Hazardous (Classified)Locations


— 67 —

Annex F (informative) — United States Major Deviations

THE TEXT OF ANNEX F HAS BEEN ADDED; THE UNDERLINING HAS BEEN OMITTED FORCLARITY

General. Group I is excluded from the scope of this document, and all associated text has been deleted.

General Marking. The words "CAUTION" and “WARNING” have been added as a prefix to requiredprecautionary markings.

General Certification. All text has been deleted that inferred that third-party certification was required.

1 This standard also requires conformance to the applicable requirements for similar apparatus foruse in unclassified locations.

Text has been added to conform to U.S. practice for hazardous locations, electrical apparatus.

2 Standards no longer referenced in the document text have been shown as strike-through text.

7.1.2 Standard requires determination of RTI in accordance with UL 746B, not ISO 216.

Revised text is consistent with US practice for ordinary locations.

9.2 & 9.3 Requirements for "Special Fasteners" have been deleted.

Deletion of "Special Fasteners" is related to Group I apparatus, which has been excluded fromthe scope of this document.

15 Mandatory external bonding terminal has been deleted. U.S. term of "equipment grounding" hasbeen used in place of "earthing."

NEC does not include requirements for the connection of an external bonding terminal. It shouldbe noted that providing such a terminal has not been prohibited. Term "equipment grounding" wasadded to align with NEC.

16.6 Text to allow non-NPT threaded entries in accordance with the 1999 NEC added.

Change required to align with NEC.

16.8 Permitted temperatures at terminals have been lowered from 70 °C to 60 °C.

Change required to align with NEC.

23.4.3.1 & Table 4. Text and table have been revised to show the height and mass as examples, notrequirements.

Required test is a specific energy; height and mass are examples provided to yield the requiredenergy.

23.4.3.1 Specific requirement has been added to ambients below -20 °C.

Text was revised to permit testing of low thermal mass samples while still achieving the intendedresults. Details on low ambient test were added to allow consistency.


— 68 —

23.4.3.2 Specific requirement has been added to ambients below -20 °C.

Text was revised to permit testing of low thermal-mass samples while still achieving the intendedresults. Details on low-ambient test were added to allow consistency.

23.4.4 Test requirement has been added for enclosures marked with a "Type" designation.

To accommodate U.S. industry practice.

26 Text deleted dealing with repaired apparatus.

Text referrred to IEC 60079-17, which has not been accepted in the U.S.

27.2 b)1)/ b)2) Additional markings of "Class I" and "Zone" have been added.

Added marking is a 1999 NEC requirement.

27.2 c) An "A" prefix has been added to "Ex."

Added marking is to designate apparatus conforming to these U.S. requirements and the markingrequirements of the 1999 NEC.

27.2 h) The requirement for a Certificate has been deleted.

A Certificate is not consistent with U.S. industry practice.

27.2 i) Requirements for "X" mark after Certificate reference have been replaced with installationinstructions or reference to specific installation instructions.

Reference with installation instructions or reference to specific installation instructions is consistentwith current U.S. industry practice.

27.6 The marking of small components has been revised to accommodate the marking required by the1999 NEC and to allow for marking of the smallest unit package.

Added marking complies with the marking requirements of the 1999 NEC and conforms to U.S.industry practice.

27.9 Requirements for identification on non-NPT threaded entries has been added.

Added marking complies with the marking requirements of the 1999 NEC.

Annex A Added notes provide a reference to NFPA 497 for U.S. gas classification, and also provide theU.S. definitions for groups.

Provide a reference to the U.S. gas-classification document and provide the gas group definitionsfrom the 1999 NEC.

Annex E Added a list of common U.S. standards for industrial equipment.

Added ordinary location standards commonly applied to hazardous (classified) location electricalequipment.


Developing and promulgating technically sound consensus standards, recommended practices, and technical reports is one of ISA’s primary goals. To achieve this goal, the Standards and Practices Department relies on the technical expertise and efforts of volunteer committee members, chairmen, and reviewers.

ISA is an American National Standards Institute (ANSI) accredited organization. ISA administers United States Technical Advisory Groups (USTAGs) and provides secretariat support for International Electrotechnical Commission (IEC) and International Organization for Standardization (ISO) committees that develop process measurement and control standards. To obtain additional information on the Society’s standards program, please write:

ISAAttn: Standards Department67 Alexander DriveP.O. Box 12277Research Triangle Park, NC 27709

ISBN: 1-55617-710-0


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