AS-NZS 60079-14: Explosive atmospheres - Electrical installations design, selection and erection

2009·8.6 MB·English

by  Standards New Zealand

AS-NZS 60079-14 (2009) (English): Explosive
atmospheres - Electrical installations design,
selection and erection [By Authority of New Zealand
Electricity (Safety) Regulations 2010 (SR 2010/36)]
We will sell to no man,
we will not deny or defer to any man either justice or right.
Magna Carta— T ūtohinga Nui
Kore rawa e hoko ki te tangata, e kore e whakakhoretia,
ā
e tautuku rnei te tangata ki te ture, tika ranei.
ā

AS / NZS 60079.14:2009
6
Australian/New Zealand Standard ™
Explosive atmospheres
STANDARDS
NEW ZEALAND
Part 14: Electrical installations design,
PAEREWA A OTEA ROA
selection and erection
(I EC 60079-14, Ed. 4.0(2007) MOD)
STANDARDS
Australia
AS/NZS 60079.14:2009
This Joint Australian/New Zealand Standard was prepared by Joint Technical
Committee EL-O 14, Equipment for Explosive Atmospheres, It was approved on
behalf of the Council of Standards Australia on 13 August 2009 and on behalf of
the Council of Standards New Zealand on I J September 2009.
This Standard was published on 18 September 2009.
The following are represented on Committee EL-014:
Auckland Regional Chamber of Commerce
Australian Chamber of Commerce and Industry
Australian Industry Group
Australian Institute of Petroleum Ltd
Australian Petroleum Production and Exploration Association
Department of Mines and Energy, Qld
Electrical Compliance Testing Association
Energy Networks Association
Engineers Australia
Institute of Instrumentation, Control and Automation Australia Inc.
Institution of Professional Engineers New Zealand
Mining Electrical and Mining Mechanical Engineering Society
National Electrical and Communications Association
New Zealand Employers and Manufacturers Association
NS W Department of Primary Industries, 1\1 ineral Resources
The Aviation and Marine Engineers Associations
Workcover New South Wales
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This Siandard was issued in draji form for commenl as DR 08193.
AS/NZS 60079.14:2009
Australian/New Zealand Standard™
Explosive atmospheres
Part 14: Electrical installations design,
selection and erection
(lEe 60079-14, Ed. 4.0(2007) MOD)
First published as AS/NZS 60079.14:2009.
COPYRIGHT
© Standards Australia/Standards New Zealand
All rights are reserved. No part of this work may be reproduced or copied in any form or by
any means, electronic or mechanical. including photocopying, without the written
permission of the publisher.
Jointly published by Standards Australia, GPO Box 476, Sydney, NSW 2001 and Standards
New Zealand, Private Bag 2439, Wellington 6020
ISBN 0 7337 9242 1
ii
PREFACE
This Standard was prepared by the Joint Standards Australia/Standards New Zealand Committee
EL-O 4, Equipment for Explosive Atmospheres. In conjunction with AS/NZS 60079-17, it will
J
replace the AS/NZS 2381, AS 2381 and AS 1076 series, two years after publication. After this
time the AS/NZS 2381, AS 2381 and AS 1076 series will be withdrawn. This Standard, in
conjunction with AS/NZS 60079.17, wi II also replace AS/NZS 61241.14, two years after
pUblication. After this time AS/NZS 61241.14 will be withdrawn.
The objective of this Standard is to set out the requirements for the design, selection and
ereetion of electrical installations in hazardous areas associated with explosive atmospheres;
these requirements are in addition to the requirements for electrical installations in non
hazardous areas.
'["his Standard is an adoption with national modifications and has been reproduced from
lEe 60079-14, EdA.0(2007), Explosive atmospheres - Pari 14: Electrical installations de.)·ign,
selection and erection. It has been varied as indicated to take account of Australian/New
Zealand conditions and for the protection of human health and safety, a legitimate reason under
the w'ro Agreement on Technical Barriers to Trade (TBT).
Variations to lEe 60079-14, Ed. 4.0(2007)) are indicated at the appropriate places throughout
this Standard. Strikethrough (s)(ample) identifies lEe text, tables and figures, that for the
purposes of this Australian/New Zealand Standard, are deleted. Where text, tables or figures are
added, each is set in its proper place and identified by shad ing (exa1J1pJe). Added figures are not
themselves shaded, but are identified by a shaded border.
The adoption of this Standard forms part of the strategic objective established by Standards
Australia and Standards New Zealand for adoption of all of the lEe 60079 series.
The change to the lEe based Standard introduces changes in both technical content and
presentation. However many of the technical changes are also introduced as a result of changes
within the I Ee as part of the fourth edition of lEe 60079-14.
Included in this Standard are selected details and informative annexes from
AS/NZS 2381.1 :2005 that are considered appropriate to retain.
Significant technical changes included in this Standard, with rcspect to the previous lEe edition
are as follows:
(a) Equipment Protection Lcvels (EPLs) have been introduced and are explained in Annex l.
(b) Dust requirements included from AS/NZS 61241.14.
NOTE: Dust requirements are included as an interim presentation for the purpose of this edition
and will be refined in a next edition with other required technical changes.
As this Standard is reproduced from an International Standard, the following applies:
(i) Its number does not appear on each page of text and its identity is shown only on the
cover and title page.
(ii) A full point should be substituted for a comma when referring to a decimal marker.
The terms 'normative' and 'informative' are used to define the application of the annex to
which they apply. A normative annex is an integral part of a Standard, whereas an informative
annex is only for information and guidance.
iii
CONTENTS
Page
Introduction ...................................................... . '" vi
Scope .. .. 1
2 Normative references ....... . .2
3 Terms and definitions .............. .. . ........ 7
3.1 General ................................... . .. ............ 7
3.2 Hazardous areas ................. .. ...................... 7
3.3 Flameproof enclosure ......................................... .. ................................ 9
3.4 I ncreased safety .................. . .. 9
3.5 Intrinsic safety - General ........................................... .. .............. 9
3.6 Intrinsic safety parameters ........... .. ..................................................... 10
3.7 Pressurization.. ...... ...... ............ .. .............................. .. . ...... 10
3.8 Type of protection 'n' ................................................. . ......... 11
3.12 dust ignition protection.. ............... . .. . . ........... 12
3.13 Electrical supply systems ..... .. . ... 12
3.14 Equipment .................................... 12
4 General .................................. .. .. .............................................. 13
4.1 General requirements ......................... . ............................................. 13
4.2 Documentation .................................. .. ............. 14
4.3 Assurance of conformity of equipment ....................... .. ................ 15
4.4 COllJpetet'H:;yQ blalificatiens of person nel ................. '.. .... . .. .. .. .............. 19
5 Selection of equipment (excluding cables and conduits)............. .. ............................. 19
5.1 Information requirements ................................................................................. 19
5.2 Zones .......................................................................................................... 19
5.3 Relationship between Equipment protection levels (EPLs) and zones .................. 19
5.4 Selection of equipment according to EPLs . ........ . . ................................... 20
5.5 Selection according to equipment grouping .................. .. .25
5.6 Selection according to the ignition temperature of the gas, vapour or dust
and ambient temperature ..... ...... ......... ............... ................... .. ........ . 25
5.7 Selection of radiating equipment for dust ......................... .. .28
5.8 Selection of ultrasonic equipment for dust. ................................................... .. 29
5.9 External influences ............................................................ . 30
5.10 Light metals as construction materials ...................... ......... ... ..... ......... ......... . 31
5.11 Transportable, portable and personal equipmenL ............................................... 31
5.12 Selection of rotating electrical machines ........................... .. . ........... 32
5.13 Luminaires.. .. ..................................................................... . .. .......... 33
5.14 Plugs and socket outlets for dust ......................................... . . ............ 33
6 Protection from dangerous (incendive) sparkillg .............................. .. .. .................... 33
6.1 Danger from live parts .............................................. . . ........................... 33
6.2 Danger from exposed and extraneous conductive parts. ............. ............ 33
6.3 Potential equalization........... .. ......... . ................ .. ............. . 35
6.4 Static electricity ................................................................................................ 36
6.5 Lightning protection ......................................... . 37
6.6 Electromagnetic radiation ....................... .. ...37
6.7 Cathodically protected metallic parts ...................... . . .. 37
6.8 Ig n ition by optical radiation ... .. .................. 38
iv
Page
7 Electrical protection... ..................... ......... " ..... 38
7.1 General. ...................... . .38
7.2 Rotating electrical machines. . ... " ...... 38
7.3 Transformers ........................ "'" ............. 39
7.4 Resistance heating devices"" ..................................... " .. . . ................. 39
8 Emergency switch-off and electrical isolation ................ . . .............. 39
8.1 Emergency switch-off....... ................. . ................ . . ............................ 39
8.2 Electrical isolation ...... . ............... " ..... . . .... 40
9 Wiring systems ........... " .. "............... . ..................................... . 40
9.1 General. ............. . . ....... 40
9.2 Aluminium conductors ........ .. .......... " ....... 40
9.3 Cables ........... ......... , .. , ............................... . ..... 40
9.4 Conduit systems ...... . .......... . ..................... " ...................................... 47
9.5 Cable and conduit systems ...... . ............... ,," ., ......... .... ......... . .. 48
9.6 Installation requirements......... . .......... ... ........... ........... .,. .......... . ..... " ..... 48
1 0 Additional requirements for type of protection 'd' Flameproof enclosures.......... . .... 50
10.1 GeneraL ......................... ".. ........... ................... . ..... " 50
10.2 Solid obstacles ..... " .......... " ....................... " ....... ".. ............. . ....... 50
10.3 Protection of flameproof joints.... .... . ................... ". . .. 50
1 0.4 Cable entry systems" ................................... . . .... 51
10.5 Conduit systems ............................................ . .................... "" ......... 53
10.6 Motors. .... . .... " .. " ........ " ..................... . . ... 54
11 Additional requirements for type of protection Ie' - Increased safety" ........................... 55
11.1 Degree of ingress protection of enclosures (IEC 60034-5 and IEC 60529) .. " ....... 55
11.2 Wiring systems ...... " .... .." .................. ,,".... . ........ " .... 55
11.3 Cage induction motors ...................... . .............. " " .. " ..................... , .. "......... 56
11.4 Luminaires " ........... " ... .. .................. " ... """ .................. 58
12 Additional requirements for types of protection 'i' -Intrinsic safety"""" ....... "" .. " ..... " .. 58
12.1 Introductory remark ... ".""" ......... " ......... ,," .. "". " ... " " ...... " ...... " .......... " 58
12.2 Installations to meet the requirements of EPL 1Gb' or 'Gc' ... """..... . ........ 59
12.3 Installations to meet the requirements of EPL 'Ga' """'" ..... "" ........ """,, .... ""." 67
12.4 Special applications "" ..... " """" ... 69
13 Additional requirements for pressurized enclosures ......... "... ..""",, ..... "" .. .. "".69
13.1 Type of protection 'p'""" ..... " ..... "..... .. ..................... . . 69
13.2 Motors ..................................... .. ...... " ................. " ..... . .. .... 73
13.3 Type of protection 'pO' "" ............................ " ...... " .. . .. .... " ...... 74
13.4 Rooms for explosive gas atmosphere .. " ....... " ....... " .. 76
14 Additional requirements for type of protection 'n' " ...................................................... 76
14.1 General.. .. ................................. "" ............ .................. .76
14.2 Degree of ingress protection of enclosures (IEC 60034-5 and IEC 60529) . .76
14.3 Wiring systems ..................... ............. . ..................................................... 77
14.4 Motors ..... ..... ... ... .......... ... '''''' ...................................... 78
14.5 Luminaires ........... ........... ................ ................. .. ..... 79
15 Additional requirements for type of protection '0'- Oil immersion ...... " ..... 79
16 Additional requirements for type of protection 'q' - Powder filling " .... ".................... 79
17 Additional requirements for type of protection 'm' Encapsulation ............................ 79
v
Page
18 Additional requirements for type of protection 'to' - Protection by enclosure .... .. . .. 79
18.1 Practices A and B ........... . ..79
18.2 Practice A ................ ....... ................. ............. ........... ......... ........ .. 79
18.3 Practice B............................................ .... ................... ............. .80
18.4 Motors supplied at varying frequency and voltages ..... . . .................. 80
19 Protection by ventilation Ex 'v' .... . . . ...... . ........ ,. .............................. . . ....... 81
Annex A (normative) Verification of intrinsically safe circuits with more than one
associated apparatus with linear current/voltage characteristics. .............. . ................ 82
Annex B (informative) Methods of determining the maximum system voltages and
currents in intrinsically safe circuits with more than one associated apparatus with
linear current/voltage characteristics (as required by Annex A) .................................... 83
Annex C (informative) Determination of cable parameters. . ....................................... 86
Annex D (informative) Safe work procedure guidelines for explosive gas atmospheres ...... 88
Annex E (normative) Potential stator winding discharge risk assessment - Ignition risk
factors ............................................................................................ . . ... 89
Annex f= (normative) Knowledge, skills and comf:)etencies of resf:)onsible f:)ersons,
olgeratives and desisners ................................... ,.... ............. . ........... . ...... 90
Annex G (informative) Examples of dust layers of excessive thickness ........... . 93
Annex H (normative) Frictional sparking risks with light metals and their alloys .................. 94
Annex I (informative) Introduction of an alternative risk assessment method
encompassing "equipment protection levels" for Ex equipment ........... '" ...... 95
100
104
;.';·i;;.,~.,:l",£,,":,,'t:~:.~:'::;.:;t,.;;.~ ..... 1 05
. . .107
t\nn~K'ZE ... 113
Bibliography. ..116
vi
INTRODUCTION
Preventive measures to reduce the explosion risk from flammable materials are based on
three principles, which shall be applied in the following order:
1. Substitution
2. Control
3. Mitigation
Substitution involves, for example, replacing a flammable material by one which is either not
flammable or less flammable.
Control involves, for example
a) reducing the quantity of flammables;
b) avoiding or minimising releases;
c) controlling the release;
d) preventing the formation of an explosive atmosphere;
e) collecting and containing releases; and
f) avoiding ignition sources.
NOTE 1 With the exception of item f), all of the above are part of the process of hazardous area classification.
Mitigation involves, for example:
a) reducing the number of people exposed;
b) providing measures to avoid the propagation of an explosion;
c) providing explosion pressure relief;
d) providing explosion pressure suppression; and
e) providing suitable personal protective equipment.
NOTE 2 The above items are part of consequence management when considering risk.
Once the principles of substitution and control (items a) to e)) have been applied, the
remaining hazardous areas should be classified into zones according to the likelihood of an
Aslt\izs
expl()s,ive ... ~tr1l0sphere being .. presellt. uJsee 60:Q79, 10;11 EC 60079 10 or
AS/f',IZSAB1241,:tOIEC 61241 1DjIE(}6:OQ'l,~,;;JOZ?} Such classification, which may be used in
conjunction with an assessment of the consequences of an ignition, allows equipment
protection levels to be determined and hence appropriate types of protection to be specified
for each location.
For an explosion to occur, an explosive atmosphere and a source of ignition need to co-exist.
Protective measures aim to reduce, to an acceptable level, the likelihood that the electrical
installation could become a source of ignition.
By careful design of the electrical installation, it is frequently possible to locate much of the
electrical equipment in less hazardous or non-hazardous areas.
When electrical equipment is to be installed in areas where dangerous concentrations and
quantities of flammable gases, vapours, mists or dusts may be present in the atmosphere,
protective measures are applied to reduce the likelihood of explosion due to ignition by arcs,
sparks or hot surfaces, produced either in normal operation or under specified fault
conditions.