INTERNATIONAL STANDARD IEC 60079-0
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INTERNATIONAL IEC
STANDARD 60079-0
F ourth edition
2004-01
Electrical apparatus for explosive
gas atmospheres –
Part 0:
General requirements
T his E nglish-language v ersion is derived from the original
b ilingual p ublication by leaving out all French-language
p ages. Missing page numbers correspond to the French-
language pages.
R eference number
IEC 60079-0:2004(E)
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INTERNATIONAL IEC
STANDARD 60079-0
F ourth edition
2004-01
Electrical apparatus for explosive
gas atmospheres –
Part 0:
General requirements
© I EC 2004 Copyright - all rights reserved
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CONTENTS
F OREWORD......................................................................................................................... 11
INTRODUCTION................................................................................................................... 17
1 Scope ............................................................................................................................. 19
2 Normative references ..................................................................................................... 21
3 Terms and definitions ..................................................................................................... 27
4 Apparatus grouping and temperature classification ......................................................... 39
4.1 Apparatus grouping ............................................................................................... 39
4.2 Group II ................................................................................................................. 39
5 Temperatures ................................................................................................................. 39
5.1 Environmental influences ...................................................................................... 39
5.2 Service temperature .............................................................................................. 41
5.3 Maximum surface temperature .............................................................................. 41
5.4 Surface temperature and ignition temperature ....................................................... 43
5.5 Small components ................................................................................................. 43
6 Requirements for all electrical apparatus ........................................................................ 45
6.1 General ................................................................................................................. 45
6.2 Mechanical strength of apparatus .......................................................................... 45
6.3 Opening times ....................................................................................................... 45
6.4 Circulating currents ............................................................................................... 47
6.5 Gasket retention .................................................................................................... 47
7 Non-metallic enclosures and non-metallic parts of enclosures ........................................ 47
7.1 General ................................................................................................................. 47
7.2 Thermal endurance ............................................................................................... 49
7.3 Electrostatic charges on external non-metallic materials of enclosures .................. 49
7.4 Threaded holes ..................................................................................................... 51
8 Enclosures containing light metals.................................................................................. 53
8.1 Material composition ............................................................................................. 53
8.2 Threaded holes ..................................................................................................... 53
Fasteners ............................................................................................................................. 53
9.1 General ................................................................................................................. 53
9.2 Special fasteners................................................................................................... 55
9.3 Holes for special fasteners .................................................................................... 55
10 Interlocking devices ........................................................................................................ 59
11 Bushings ........................................................................................................................ 59
12 Materials used for cementing.......................................................................................... 59
13 Ex components ............................................................................................................... 59
13.1 General ................................................................................................................. 59
13.2 Mounting internal to apparatus .............................................................................. 59
13.3 Mounting external to apparatus ............................................................................. 61
14 Connection facilities and terminal compartments ............................................................ 61
14.1 General ................................................................................................................. 61
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14.2 Connection space.................................................................................................. 61
14.3 Type of protection ................................................................................................. 61
14.4 Creepage and clearance ....................................................................................... 61
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15 Connection facilities for earthing or bonding conductors ................................................. 61
15.1 Internal.................................................................................................................. 61
15.2 External................................................................................................................. 61
15.3 Apparatus not requiring earthing ........................................................................... 63
15.4 Size of conductor connection................................................................................. 63
15.5 Protection against corrosion .................................................................................. 63
15.6 Secureness ........................................................................................................... 63
16 Entries into enclosures ................................................................................................... 65
16.1 General ................................................................................................................. 65
16.2 Identification of entries .......................................................................................... 65
16.3 Cable glands ......................................................................................................... 65
16.4 Blanking elements ................................................................................................. 65
16.5 Conductor temperature.......................................................................................... 65
17 Supplementary requirements for rotating electrical machines ......................................... 67
17.1 Fans and fan hoods ............................................................................................... 67
17.2 Ventilation openings for external fans .................................................................... 67
17.3 Construction and mounting of the ventilating systems ........................................... 69
17.4 Clearances for the ventilating system .................................................................... 69
17.5 Materials for external fans and fan hoods .............................................................. 69
17.6 Equipotential bonding conductors .......................................................................... 69
18 Supplementary requirements for switchgear ................................................................... 69
18.1 Flammable dielectric ............................................................................................. 69
18.2 Disconnectors ....................................................................................................... 71
18.3 Group I – Provisions for locking............................................................................. 71
18.4 Doors and covers .................................................................................................. 71
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19 Supplementary requirements for fuses ........................................................................... 73
20 Supplementary requirements for plugs and sockets ........................................................ 73
20.1 Interlocking ........................................................................................................... 73
20.2 Energized plugs .................................................................................................... 73
21 Supplementary requirements for luminaires .................................................................... 73
21.1 General ................................................................................................................. 73
21.2 Covers .................................................................................................................. 75
21.3 Special lamps ........................................................................................................ 75
22 Supplementary requirements for caplights and handlights .............................................. 75
22.1 Group I caplights and handlights ........................................................................... 75
22.2 Group II caplights and handlights ......................................................................... 75
23 Apparatus incorporating cells and batteries .................................................................... 77
23.1 Batteries................................................................................................................ 77
23.2 Cell types .............................................................................................................. 77
23.3 Cells in a battery ................................................................................................... 79
23.4 Ratings of batteries ............................................................................................... 79
23.5 Mixture of cells ...................................................................................................... 79
23.6 Interchangeability .................................................................................................. 79
23.7 Charging of primary batteries ................................................................................ 79
23.8 Leakage ................................................................................................................ 79
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23.9 Connections ....................................................................................................... 81
23.10 Orientation.......................................................................................................... 81
23.11 Replacement of cells or batteries ........................................................................ 81
24 Documentation ............................................................................................................... 81
25 Compliance of prototype or sample with documents ....................................................... 81
26 Type tests ...................................................................................................................... 81
26.1 General .............................................................................................................. 81
26.2 Test configuration ............................................................................................... 81
26.3 Tests in explosive test mixtures .......................................................................... 81
26.4 Tests of enclosures ............................................................................................ 83
26.5 Thermal tests...................................................................................................... 91
26.6 Torque test for bushings ..................................................................................... 93
26.7 Non-metallic enclosures or non-metallic parts of enclosures ............................... 95
26.8 Thermal endurance to heat ................................................................................. 95
26.9 Thermal endurance to cold ................................................................................. 97
26.10 Resistance to light .............................................................................................. 97
26.11 Resistance to chemical agents for Group I electrical apparatus .......................... 99
26.12 Earth continuity .................................................................................................. 99
26.13 Surface resistance test of parts of enclosures of non-metallic materials............ 101
26.14 Charging tests .................................................................................................. 103
26.15 Measurement of capacitance ............................................................................ 111
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27 Routine verifications and tests ...................................................................................... 111
28 Manufacturer's responsibility ........................................................................................ 111
28.1 Certificate ......................................................................................................... 111
28.2 Responsibility for marking................................................................................. 111
29 Marking ........................................................................................................................ 111
29.1 Location ........................................................................................................... 113
29.2 General ............................................................................................................ 113
29.3 Different types of protection .............................................................................. 115
29.4 Order of marking............................................................................................... 117
29.5 Ex components ................................................................................................. 117
29.6 Small apparatus and Ex components ................................................................ 117
29.7 Extremely small apparatus and Ex components ................................................ 117
29.8 Warning markings ............................................................................................. 117
29.9 Cells and batteries............................................................................................ 119
29.10 Examples of marking ........................................................................................ 119
30 Instructions................................................................................................................... 121
30.1 General ............................................................................................................ 121
30.2 Cells and batteries............................................................................................ 123
Annex A (normative) Ex cable glands................................................................................. 125
Annex B (normative) Requirements for Ex components ...................................................... 139
Annex C (informative) Example of rig for resistance to impact test ..................................... 143
B ibliography........................................................................................................................ 145
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Figure 1 – Tolerances and clearance for threaded fasteners ................................................. 57
Figure 2 – Contact surface under head of fastener with a reduced shank .............................. 57
Figure 3 – Illustration of entry points and branching points ................................................... 67
Figure 4 – Assembly of test sample for earth-continuity test................................................ 101
Figure 5 – Test piece with painted electrodes ..................................................................... 103
Figure 6 – Rubbing with a pure nylon cloth ......................................................................... 107
Figure 7 – Discharging of a container with a probe connected to earth via a 0,1 µF
capacitor............................................................................................................................. 109
Figure 8 – Charging by influence with a d.c. voltage power supply ...................................... 109
Figure A.1 – Illustration of the terms used for cable glands ................................................. 125
Figure A.2 – Rounded edge of the point of entry of the flexible cable .................................. 129
Figure C.1 – Example of rig for resistance to impact test .................................................... 143
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Table 1 – Ambient temperatures in service and additional marking ....................................... 41
Table 2 – Classification of maximum surface temperatures for Group II electrical
apparatus ............................................................................................................................. 43
Table 3 – Assessment for T4 classification according to component size and ambient
temperature .......................................................................................................................... 43
Table 4 – Limitations of areas ............................................................................................... 51
Table 5 – Minimum cross-sectional area of protective conductors ......................................... 63
Table 6 – Primary cells ......................................................................................................... 77
Table 7 – Secondary cells ..................................................................................................... 79
Table 8 – Tests for resistance to impact................................................................................ 87
Table 9 – Torque to be applied to the stem of bushing used for connection facilities ............. 95
Table 10 − T ext of warning markings .................................................................................. 119
Table B.1 – Clauses with which Ex components shall comply ............................................. 139
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I NTERNATIONAL ELECTROTECHNICAL COMMISSION
__________
E LECTRICAL APPARATUS FOR EXPLOSIVE
GAS ATMOSPHERES –
Part 0: General requirements
FOREWORD
1 ) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
I nternational Standard IEC 60079-0 has been prepared by technical committee 31: Electrical
apparatus for explosive atmospheres.
This fourth edition cancels and replaces the third edition, published in 1998, and constitutes a
full technical revision.
The significant changes with respect to the previous edition are listed below:
• S tandard atmospheric conditions re-introduced
• A ll requirements for third-party certification removed
• N ew type of protection “n” introduced
• N ew apparatus standards for caplights, intrinsically safe systems, Zone 0 apparatus, and
trace heating introduced
• C larification of the status of symbol “s”
• D efinitions for symbols “U” and “X” revised to align with current usage
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• D efinition for Ex component transferred from IEC 60079-18
• N ew definitions drafted for “energy limited” parameters to allow common usage by types of
protection “i” and “n”
• N ew definitions for batteries transferred from IEC 60079-7
• D efinition added for ambient temperature
• D efinition added for continuous operating temperature (COT)
• D efinition for certificate transferred from IEC 60079-15 and revised based on
ISO/IEC 17000
• D efinition added for cable gland
• C lause 5 for temperature re-written to address the influences of ambient temperature,
internal sources of heat, and external sources of heating or cooling
• S mall component ignition test transferred from IEC 60079-11 and IEC 60079-15
• R equirements for bonding transferred from IEC 60079-7 and IEC 60079-15
• R equirements for gasket retention transferred from IEC 60079-15 for wider applicability
• R elative thermal index (RTI) added as an alternative to thermal index (TI)
• E lectrostatic requirements transferred and rationalized from IEC 60079-15 and IEC 60079-
26 to apply to all of Group I and Group II
• I ntroduction of two additional test methods to evaluate the use of non-metallic materials
with respect to the storage of electrostatic charges
•
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L ight metal requirements transferred and rationalized from IEC 60079-15 and IEC 60079-
26 to apply to all of Group I and Group II
• I ntroduction of an existing test to evaluate the use of a non-metallic enclosure wall in an
earth bonding connection
• C lause 16 rewritten to align with industry usage of the terms c able gland a nd c onduit
e ntry .
• E quipotential bonding requirements for machines transferred from IEC 60079-7 and
IEC 60079-15
• R equirement for disconnectors in switchgear and luminaires revised to provide IP20
protection for live parts and include additional marking
• G eneral requirements for cells and batteries transferred from IEC 60079-7 and IEC 60079-
15
• I mpact test revised to specify drop height in lieu of energy
• C larification of application of 5 °C and 10 °C temperature margins to type-tested samples
• C larification of order of tests for metallic materials
• C larification of number of samples and order of tests for non-metallic materials
• C larification of order of marking
• C larification of marking details for associated apparatus
• C larification of marking of specific gases
• C larification of marking of temperature class
• C larification of usage of compulsory certificate number
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6 0079-0 I EC:2004 – 15 –
• C larification of marking of small apparatus
• C ompilation of all warning markings into a table
• C larification of marking examples
• A ddition of a clause on instructions
• D eletion of Annex A as information is available in more appropriate standards (IEC 60079-
20)
• R evision and clarification of Annex A (previously Annex B) to accommodate term c able
g land
T he text of this standard is based on the following documents:
F DIS Report on voting
3 1/474A/FDIS 31/487/RVD
F ull information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
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The committee has decided that the contents of this publication will remain unchanged until
2008. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
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INTRODUCTION
I t is acknowledged that, with developments in technology, it will be possible to achieve the
objectives of the IEC 60079 series of standards in respect of explosion prevention by methods
that are not yet fully defined. Where a manufacturer wishes to take advantage of such
developments, this International Standard, as well as other standards in the IEC 60079 series,
may be applied in part. It is intended that the manufacturer prepare documentation that clearly
defines how the IEC 60079 series of standards has been applied, together with a full
explanation of the additional techniques employed. In this case, the letter “s” has been
reserved to indicate a method of protection that is not fully defined in the standards.
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Compliance with this standard cannot be claimed in these circumstances.
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E LECTRICAL APPARATUS FOR EXPLOSIVE
GAS ATMOSPHERES –
Part 0: General requirements
1 S cope
T his part of IEC 60079 specifies the general requirements for construction, testing and
marking of electrical apparatus and Ex components intended for use in explosive gas
atmospheres.
Unless modified by one of the parts in the IEC 60079 series, electrical apparatus complying
with this standard is intended for use in hazardous areas in which explosive gas atmospheres,
caused by mixtures of air and gases, vapours or mists, exist under normal atmospheric
conditions of
• t emperature –20 °C to +60 °C;
• p ressure 80 kPa (0,8 bar) to 110 kPa (1,1 bar); and
• a ir with normal oxygen content, typically 21 % v/v.
The application of electrical apparatus in atmospheric conditions outside this range may need
special consideration.
N OTE 1 The determination of the maximum surface temperature is based on an operational ambient temperature
of –20 °C to +40 °C, if not otherwise specified by the manufacturer. See also 5.1.1.
NOTE 2 In designing apparatus for operation in explosive gas atmospheres under conditions other than the
atmospheric conditions given above, this standard may be used as a guide. However, additional testing related
specifically to the intended conditions of use is recommended. This is particularly important when the types of
protection ‘flameproof enclosures “d”’ (IEC 60079-1) and ‘intrinsic safety “i”’ (IEC 60079-11) are applied.
NOTE 3 Requirements given in this standard result from an ignition hazard assessment made on electrical
equipment. The ignition sources taken into account are those found associated with this type of equipment, such as
hot surfaces, mechanically generated sparks, thermite reactions, electrical arcing and static electric discharge in
normal industrial environments. For other ignition sources like adiabatic compression, shock waves, exothermic
chemical reaction, self ignition of dust, naked flames, hot gases/liquids the apparatus are subjected to a hazard
analysis that identifies and lists all of the potential sources of ignition by the electrical apparatus and the measures
to be applied to prevent them becoming effective.
T his standard does not specify requirements for safety, other than those directly related to the
explosion risk.
This standard is supplemented or modified by the following parts of IEC 60079 concerning
specific types of protection:
– IEC 60079-1: Flameproof enclosures "d";
– IEC 60079-2: Pressurized enclosures "p";
– IEC 60079-5: Powder filling "q";
– IEC 60079-6: Oil immersion "o";
– IEC 60079-7: Increased safety "e";
I EC 60079-11: Intrinsic safety "i";
–
I EC 60079-15: Type of protection “n”;
–
– IEC 60079-18: Encapsulation "m".
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This standard is supplemented or modified by the following apparatus standards:
I EC 60079-25
–
I EC 60079-26
–
I EC 62013-1
–
I EC 62086-1.
–
This part of IEC 60079, along with other parts in the IEC 60079 series and the additional
standards mentioned above, is not applicable to the construction of electromedical apparatus,
shot-firing exploders, test devices for exploders and for shot-firing circuits.
2 Normative references
T he following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC 60034-5 , Rotating electrical machines – Part 5: Degrees of protection provided by the
integral design of rotating electrical machines (IP code) – Classification
I EC 60079-1 , Electrical apparatus for explosive gas atmospheres – P art 1: F lameproof
enclosures ”d”
I EC 60079-2 , Electrical apparatus for explosive gas atmospheres – P art 2: Pressurized
enclosures "p"
I EC 60079-4 , Electrical apparatus for explosive gas atmospheres – P art 4: Method of test
for ignition temperature
I EC 60079-5 , Electrical apparatus for explosive gas atmospheres – P art 5: Powder filling "q"
I EC 60079-6, E lectrical apparatus for explosive gas atmospheres – Part 6: Oil-immersion "o"
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I EC 60079-7, E lectrical apparatus for explosive gas atmospheres – Part 7: Increased safety "e"
I EC 60079-10, E lectrical apparatus for explosive gas atmospheres – Part 10: Classification of
hazardous areas
I EC 60079-11, E lectrical apparatus for explosive gas atmospheres – Part 11: Intrinsic safety "i"
I EC 60079-15, E lectrical apparatus for explosive gas atmospheres – Part 15: Type of
protection "n"
I EC 60079-18, E lectrical apparatus for explosive gas atmospheres – Part 18: Encapsulation "m"
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IEC 60079-25: E lectrical apparatus for explosive gas atmospheres – Part 25: Intrinsically safe
systems 1
I EC 60079-26: E lectrical apparatus for explosive gas atmospheres – Part 26: Construction,
test and marking of zone 0 electrical apparatus 2
I EC 60086-1, P rimary batteries – Part 1: General
I EC 60095-1, L ead-acid starter batteries – Part 1: General requirements and methods of test
I EC 60192, L ow-pressure sodium vapour lamps – Performance specifications
I EC 60216-1, E lectrical insulating materials – Properties of thermal endurance – Part 1: Ageing
procedures and evaluation of test results
I EC 60216-2, G uide for the determination of thermal endurance properties of electrical
insulating materials – Part 2: Choice of test criteria
I EC 60423, C onduits for electrical purposes – Outside diameters of conduits for electrical
installations and threads for conduits and fittings
I EC 60529, D egrees of protection provided by enclosures (IP Code)
I EC 60622, S econdary cells and batteries containing alkaline or other non-acid electrolytes –
Sealed nickel-cadmium prismatic rechargeable single cells
I EC 60623, S econdary cells and batteries containing alkaline or other non-acid electrolytes –
Vented nickel-cadmium prismatic rechargeable single cells
I EC 60662, H igh-pressure sodium vapour lamps
I EC 60947-1, L ow-voltage switchgear and controlgear – Part 1: General rules
I EC 61056-1, G eneral-purpose lead-acid cells and batteries (valve-regulated types) – Part 1:
General requirements, functional characteristics – Methods of test
I EC 61150, A lkaline secondary cells and batteries – Sealed nickel-cadmium rechargeable
monobloc batteries in button cell design
I EC 61436, S econdary cells and batteries containing alkaline or other non-acid electrolytes –
Sealed nickel-metal hydride rechargeable single cells
I EC 61951-1, S econdary cells and batteries containing alkalinei and other non-acid
electrolytes – Portable sealed rechargeable single cells – Part 1: Nickel-cadmium
I EC 62013-1, C aplights for use in mines susceptible to firedamp – Part 1: General
requirements – Construction and testing in relation to the risk of explosion
I EC 62086-1: E lectrical apparatus for explosive gas atmospheres – Electrical resistance trace
heating – Part 1: General and testing requirements
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— ——————
1 T o be published.
2 In preparation.
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ISO 48, R ubber, vulcanized or thermoplastic – Determination of hardness (hardness between
10 IRHD and 100 IRHD)
I SO 178, P lastics – Determination of flexural properties
I SO 179, P lastics – Determination of Charpy impact properties
I SO 262, I SO general-purpose metric screw threads – Selected sizes for screws, bolts and
nuts
I SO 273, F asteners – Clearance holes for bolts and screws
I SO 286-2, I SO system of limits and fits – Part 2: Tables of standard tolerance grades and
limit deviations for holes and shafts
I SO 527-2, P lastics – Determination of tensile properties – Part 2: Test conditions for
moulding and extrusion plastics
I SO 965-1, I SO general-purpose metric screw threads – Tolerances – Part 1: Principles and
basic data
I SO 965-3, I SO general-purpose metric screw threads – Tolerances – Part 3: Deviations for
constructional screw threads
I SO 1817, R ubber, vulcanized – Determination of the effect of liquids
I SO 4014, H exagon head bolts – Product grades A and B
I SO 4017, H exagon head screws – Product grades A and B
I SO 4026, H exagon socket set screws with flat point
I SO 4027, H exagon socket set screws with cone point
I SO 4028, H exagon socket set screws with dog point
I SO 4029, H exagon socket set screws with cup point
I SO 4032, H exagon nuts, style 1 – Product grades A and B
I SO 4762, H exagon socket head cap screws
I SO 4892-1, P lastics – Methods of exposure to laboratory light sources – Part 1: General
guidance
A NSI/UL 746B, P olymeric Materials – Long-Term Property Evaluations
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3 T erms and definitions
F or the purposes of this document, the following definitions apply.
3 .1
ambient temperature
t emperature of the air or other media, in the immediate vicinity of the apparatus or component
N OTE This does not refer to the temperature of any process media, unless the apparatus or component is totally
immersed in the process media. See 5.1.1.
3 .2
associated apparatus
e lectrical apparatus which contains both energy-limited and non-energy-limited circuits and is
constructed so that the non energy-limited circuits cannot adversely affect the energy-limited
circuits
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N OTE Associated apparatus may be either:
a) electrical apparatus which has an alternative type of protection included in this standard for use in the
appropriate explosive gas atmosphere;
b) electrical apparatus not so protected and which therefore is not to be used within an explosive gas
atmosphere, for example, a recorder which is not of itself in an explosive gas atmosphere but is connected to a
thermocouple situated within an explosive gas atmosphere where only the recorder input circuit is energy limited.
3 .3
cells and batteries
3.3.1
battery
a ssembly of two or more cells electrically connected to each other to increase the voltage or
capacity
3 .3.2
capacity
q uantity of electricity or electric charge, which a fully charged battery can deliver under
specified conditions
3 .3.3
cell
a ssembly of electrodes and electrolyte which constitutes the smallest electrical unit of a
battery
3 .3.4
charging
a ct of forcing current through a secondary cell or battery in the opposite direction to the
normal flow to restore the energy
3 .3.5
deep discharge
e vent which reduces a cell voltage below that recommended by the cell or battery
manufacturer
3 .3.6
inherently safe (ihs) cell (or battery)
p rimary cell or battery in which the short-circuit current and maximum surface temperature are
limited to a safe value by its internal resistance
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3 .3.7
maximum open-circuit voltage (of a cell or battery)
m aximum attainable voltage under normal conditions, that is, from either a new primary cell,
or a secondary cell just after a full charge
N OTE See Tables 6 and 7 which show the maximum open-circuit voltage for acceptable cells.
3 .3.8
nominal voltage
( of a cell or battery) is that specified by the manufacturer
3 .3.9
open cell or battery
s econdary cell, or battery, having a cover provided with an opening through which gaseous
products may escape
[IEV 486-01-18]
3 .3.10
primary cell or battery
e lectrochemical system capable of producing electrical energy by chemical reaction
3 .3.11
reverse charging
a ct of forcing current through either a primary cell or secondary cell in the same direction as
the normal flow, for example, in an expired battery
3 .3.12
sealed gas-tight cell or battery
c ell or battery which remains closed and does not release either gas or liquid when operated
within the limits of charge or temperature specified by the manufacturer
N OTE 1 Such cells and batteries may be equipped with a safety device to prevent dangerously high internal
pressure. The cell or battery does not require addition to the electrolyte and is designed to operate during its life in
its original sealed state.
NOTE 2 The above definition is taken from IEC 60079-11. It differs from the definitions in IEV 486-01-20 and IEV
486-01-21 by virtue of the fact that it applies to either a cell or battery.
3 .3.13
sealed valve-regulated cell or battery
c ell or battery which is closed under normal conditions but which has an arrangement which
allows the escape of gas if the internal pressure exceeds a pre-determined value. The cell
cannot normally receive an addition to the electrolyte
[IEV 486-01-20 and IEV 486-01-21, modified]
3 .3.14
secondary cell or battery
e lectrically rechargeable electrochemical system capable of storing electrical energy and
delivering it by chemical reaction
3 .4
bushing
i nsulating device carrying one or more conductors through an internal or external wall of an
enclosure
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3 .5
cable gland
d evice permitting the introduction of one or more electric and/or fibre optics cables into an
electrical apparatus so as to maintain the relevant type of protection
3 .5.1
clamping device
e lement of a cable gland for preventing tension or torsion in the cable from being transmitted
to the connections
3 .5.2
compression element
e lement of a cable gland acting on the sealing ring to enable the latter to fulfil its function
3 .5.3
sealing ring
r ing used in a cable gland or with a conduit entry to ensure the sealing between the entry and
the cable or conduit
3 .5.4
Ex cable gland
c able gland tested separately from the apparatus enclosure but certified as an apparatus and
which can be fitted to the apparatus enclosure during installation
3 .6
certificate
d ocument that assures the conformity of a product, process, system, person, or organization
with specified requirements
N OTE The certificate may be either the supplier’s declaration of conformity or the purchaser’s recognition of
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conformity or certification (as a result of action by a third party) as defined in ISO/IEC DIS 17000.
3 .7
conduit entry
m eans of introducing a conduit into an electrical apparatus so as to maintain the relevant type
of protection
3 .8
connection facilities
t erminals, screws or other parts, used for the electrical connection of conductors of external
circuits
3 .9
continuous operating temperature (COT)
m aximum temperature which ensures the stability and integrity of the material for the
expected life of the apparatus, or part, in its intended application
3 .10
degree of protection of enclosure (IP)
n umerical classification according to IEC 60529 preceded by the symbol IP applied to the
enclosure of electrical apparatus to provide
– protection of persons against contact with, or approach to, live parts and against contact
with moving parts (other than smooth rotating shafts and the like) inside the enclosure,
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– protection of the electrical apparatus against ingress of solid foreign objects, and
– where indicated by the classification, protection of the electrical apparatus against harmful
ingress of water
N OTE The enclosure which provides the degree of protection IP is not necessarily identical to the apparatus
enclosure for the types of protection listed in Clause 1.
3 .11
electrical apparatus
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i tems applied as a whole or in part for the utilization of electrical energy
N OTE These include, amongst others, items for the generation, transmission, distribution, storage, measurement,
regulation, conversion and consumption of electrical energy and items for telecommunications.
3 .12
electrical parameters – apparatus with energy limitation
3.12.1
maximum external capacitance
Co
m aximum capacitance that can be connected to the connection facilities of the apparatus
without invalidating the type of protection
3 .12.2
maximum external inductance
Lo
m aximum value of inductance that can be connected to the connection facilities of the
apparatus without invalidating the type of protection
3 .12.3
maximum input current
Ii
m aximum current (peak a.c. or d.c.) that can be applied to the connection facilities of
apparatus without invalidating the type of protection
3 .12.4
maximum input power
Pi
p ower that can be applied to the connection facilities of apparatus without invalidating the
type of protection
3 .12.5
maximum input voltage
Ui
m aximum voltage (peak a.c. or d.c.) that can be applied to the connection facilities of
apparatus without invalidating the type of protection
3 .12.6
maximum internal capacitance
Ci
m aximum equivalent internal capacitance of the apparatus which is considered as appearing
across the connection facilities
3 .12.7
maximum internal inductance
Li
m aximum equivalent internal inductance of the apparatus which is considered as appearing at
the connection facilities
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3 .12.8
maximum output current
Io
m aximum current (peak a.c. or d.c.) in apparatus that can be taken from the connection
facilities of the apparatus
3 .12.9
maximum output power
Po
m aximum electrical power that can be taken from the apparatus
3 .12.10
maximum output voltage
Uo
m aximum voltage (peak a.c. or d.c.) that can appear at the connection facilities of the
apparatus at any applied voltage up to the maximum voltage
3 .12.11
maximum r.m.s. a.c. or d.c. voltage
Um
m aximum voltage that can be applied to the non energy-limited connection facilities of
associated apparatus without invalidating the type of protection
3 .13
enclosure
a ll the walls, doors, covers, cable glands, rods, spindles, shafts, etc. which contribute to the
type of protection and/or the degree of protection IP of the electrical apparatus
3 .14
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Ex component
p art of electrical apparatus or a module (other than an Ex cable gland), marked with the
symbol “U”, which is not intended to be used alone and requires additional consideration
when incorporated into electrical apparatus or systems for use in explosive gas atmospheres
3 .15
explosive gas atmosphere
m ixture with air, under atmospheric conditions, of flammable substances in the form of gas or
vapour, in which, after ignition, permits self-sustaining flame propagation
3 .16
explosive test mixture
s pecified explosive mixture used for the testing of electrical apparatus for explosive gas
atmospheres
3 .17
ignition temperature of an explosive gas atmosphere
l owest 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 .18
maximum surface temperature
h ighest temperature which is attained in service under the most adverse conditions (but within
the specified tolerances) by any part or surface of an electrical apparatus, which would be
able to produce an ignition of the surrounding explosive atmosphere
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