IEC 60331-3:2018
(Main)Tests for electric cables under fire conditions - Circuit integrity - Part 3: Test method for fire with shock at a temperature of at least 830 °C for cables of rated voltage up to and including 0,6/1,0 kV tested in a metal enclosure
Tests for electric cables under fire conditions - Circuit integrity - Part 3: Test method for fire with shock at a temperature of at least 830 °C for cables of rated voltage up to and including 0,6/1,0 kV tested in a metal enclosure
IEC 60331-3:2018 specifies the test method for cables which are required to maintain circuit integrity when tested in a metal enclosure and when subject to fire and mechanical shock under specified conditions. This document is applicable to cables of rated voltage not exceeding 600 V/1 000 V, including those of rated voltage below 80 V, metallic data and telecom cables and optical fibre cables. It is intended for use when testing cables not greater than 20 mm overall diameter. This document includes details for the specific point of failure, continuity checking arrangement, test sample, test procedure and test report relevant to electric power and control cables with rated voltage up to and including 600 V/1 000 V. Details for the specific point of failure, continuity checking arrangement, test sample, test procedure and test report relevant to metallic data and telecom cables and optical fibre cables are not given by IEC 60331-3. Although the scope is restricted to cables with rated voltage up to and including 0,6/1,0 kV, the procedure can be used, with the agreement of the manufacturer and the purchaser, for cables with rated voltage up to and including 1,8/3 (3,3) kV, provided that suitable fuses are used. It is not assumed that cables successfully assessed by this method, will also pass requirements for either IEC 60331-1 or IEC 60331-2. Testing to either of these two standards is to be carried out separately. Such additional performance can be recognised by the marking in accordance with IEC 60331-1:2018 Clause 11 or IEC 60331 2:2018 Clause 11. This second edition cancels and replaces the first edition published in 2009. It constitutes a technical revision. The significant technical changes with respect to the previous edition are as follows:
– extension of the scope to include metallic data and telecom cables and optical fibre cables, although details for the specific point of failure, continuity checking arrangement, test sample, test procedure and test report relevant to metallic data and telecom cables and optical fibre cables are not given by IEC 60331-3;
– improved description of the test environment;
– mandatory use of mass flow meter/controllers as the means of controlling accurately the input flow rates of fuel and air to the burner;
– improved description of the information to be included in the test report.
Essais pour câbles électriques soumis au feu – Intégrité des circuits – Partie 3: Méthode d’essai au feu pour les câbles de tension assignée au plus égale à 0,6/1,0 kV, soumis à essai sous conduit métallique avec chocs, à une température d’au moins 830 °C
L'IEC 60331-3:2018 spécifie la méthode d'essai pour les câbles nécessaires afin de conserver l'intégrité du circuit quand ils sont soumis à l'essai sous conduit métallique et exposés à un feu et à des chocs mécaniques dans des conditions spécifiées.
La présente norme s'applique aux câbles de tension assignée au plus égale à 600 V/1000 V, y compris ceux dont la tension assignée est inférieure à 80 V, aux câbles métalliques de données et de télécommunications ainsi qu'aux câbles à fibres optiques.
Elle est destinée à être utilisée pour soumettre à l'essai des câbles de diamètre externe inférieur ou égal à 20 mm.
La présente norme inclut des informations concernant le point spécifique de défaillance, le dispositif de contrôle de la continuité, l'échantillon d'essai, la procédure d'essai et le rapport d'essai pertinents pour les câbles électriques de puissance et de commande de tension assignée au plus égale à 600 V/1000 V. Les informations concernant le point spécifique de défaillance, le dispositif de contrôle de la continuité, l'échantillon d'essai, la procédure d'essai et le rapport d'essai pertinents pour les câbles métalliques de données et de télécommunications et les câbles à fibres optiques ne sont pas données dans l'IEC 60331-3.
Bien que le domaine d'application soit limité aux câbles de tension assignée au plus égale à 0,6/1,0 kV, cette procédure peut être utilisée, après accord entre le fabricant et l'acheteur, pour les câbles de tension assignée au plus égale à 1,8/3 (3,3) kV, à condition d'utiliser des fusibles appropriés.
Rien ne présume qu'un câble évalué avec succès par cette méthode satisfera également aux exigences de l'IEC 60331-1 ou l'IEC 60331-2. Les essais de ces deux normes doivent être réalisés séparément. Ces performances supplémentaires peuvent être reconnues par marquage conformément à l'Article 11 de l'IEC 60331-1 ou l'Article 11 de l'IEC 60331-2.
L'Annexe A donne la méthode de vérification du brûleur et le système de contrôle utilisé pour l'essai.
Cette deuxième édition annule et remplace la première édition parue en 2009. Elle constitue une révision technique.
Les modifications techniques majeures par rapport à l'édition précédente sont les suivantes:
– extension du domaine d'application aux câbles métalliques de données et de télécommunications et aux câbles à fibres optiques, bien que les informations concernant le point spécifique de défaillance, le dispositif de contrôle de la continuité, l'échantillon d'essai, la procédure d'essai et le rapport d'essai pour les câbles métalliques de données et de télécommunications et pour les câbles à fibres optiques ne soient pas données dans l'IEC 60331-3;
– amélioration de la description de l'environnement d'essai;
– utilisation obligatoire des débitmètres/régulateurs massiques comme moyens précis de contrôle exact des débits d'entrée de combustible et d'air au brûleur;
– amélioration de la description des informations à inclure dans le rapport d'essai.
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Standards Content (Sample)
IEC 60331-3 ®
Edition 2.0 2018-03
INTERNATIONAL
STANDARD
GROUP SAFETY PUBLICATION
Tests for electric cables under fire conditions – Circuit integrity –
Part 3: Test method for fire with shock at a temperature of at least 830 °C for
cables of rated voltage up to and including 0,6/1,0 kV tested in a metal enclosure
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.
IEC Central Office Tel.: +41 22 919 02 11
3, rue de Varembé info@iec.ch
CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.
About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigenda or an amendment might have been published.
IEC Catalogue - webstore.iec.ch/catalogue Electropedia - www.electropedia.org
The stand-alone application for consulting the entire The world's leading online dictionary of electronic and
bibliographical information on IEC International Standards, electrical terms containing 21 000 terms and definitions in
Technical Specifications, Technical Reports and other English and French, with equivalent terms in 16 additional
documents. Available for PC, Mac OS, Android Tablets and languages. Also known as the International Electrotechnical
iPad. Vocabulary (IEV) online.
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variety of criteria (reference number, text, technical French extracted from the Terms and Definitions clause of
committee,…). It also gives information on projects, replaced IEC publications issued since 2002. Some entries have been
and withdrawn publications. collected from earlier publications of IEC TC 37, 77, 86 and
CISPR.
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IEC 60331-3 ®
Edition 2.0 2018-03
INTERNATIONAL
STANDARD
GROUP SAFETY PUBLICATION
Tests for electric cables under fire conditions – Circuit integrity –
Part 3: Test method for fire with shock at a temperature of at least 830 °C for
cables of rated voltage up to and including 0,6/1,0 kV tested in a metal enclosure
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 13.220.40; 29.020; 29.060.20 ISBN 978-2-8322-5492-9
– 2 – IEC 60331-3:2018 © IEC 2018
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 8
4 Test environment . 8
5 Test apparatus . 8
5.1 Test equipment . 8
5.2 Metal enclosure . 9
5.2.1 Material and dimensions . 9
5.2.2 Metal enclosure selection . 9
5.3 Test ladder and mounting . 9
5.4 Source of heat . 15
5.4.1 Burner . 15
5.4.2 Flow meters and flow rates . 16
5.4.3 Verification . 17
5.5 Shock-producing device . 17
5.6 Positioning of source of heat . 18
5.7 Continuity checking arrangements for electric power and control cables with
rated voltage up to and including 600 V/1 000 V . 18
5.8 Fuses. 18
6 Test specimen (electric power and control cables with rated voltage up to and
including 600 V/1 000 V) . 18
6.1 Test specimen preparation . 18
6.2 Test specimen mounting . 19
7 Test procedure (electric power and control cables with rated voltage up to and
including 600 V/1 000 V) . 19
7.1 Test equipment and arrangement . 19
7.2 Electrical connections . 19
7.3 Flame and shock application . 21
7.4 Electrification . 21
8 Performance requirements (electric power and control cables with rated voltage
up to and including 600 V/1 000 V) . 22
8.1 Flame application time . 22
8.2 Acceptance criteria . 22
9 Retest procedure . 22
10 Test report (electric power and control cables with rated voltage up to and
including 600 V/1 000 V) . 22
Annex A (normative) Verification procedure for the source of heat . 23
A.1 Measuring equipment . 23
A.2 Procedure . 23
A.3 Evaluation . 24
A.4 Further verification . 24
A.5 Verification report . 24
Annex B (informative) Guidance on the choice of recommended test apparatus (burner
and venturi) . 25
Bibliography . 26
Figure 1 – Schematic diagram of test configuration . 11
Figure 2 – Recommended method of mounting the metal enclosure to the test ladder . 12
Figure 3 – Plan view of fire test equipment . 13
Figure 4 – End elevation of fire test equipment (not to scale) . 14
Figure 5 – Typical rubber bush for supporting the test ladder . 15
Figure 6 – Burner face . 16
Figure 7 – Schematic diagram of an example of a burner control system . 17
Figure 8 – Basic circuit diagram . 21
Figure A.1 – Temperature measuring arrangement . 23
Table 1 – Enclosure dimensions . 9
Table 2 – Multicore sheathed cable . 19
Table 3 – Single core unsheathed or sheathed cable . 19
– 4 – IEC 60331-3:2018 © IEC 2018
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
TESTS FOR ELECTRIC CABLES UNDER FIRE CONDITIONS –
CIRCUIT INTEGRITY –
Part 3: Test method for fire with shock at a temperature of at least 830 °C
for cables of rated voltage up to and including 0,6/1,0 kV tested
in a metal enclosure
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 itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
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.
International Standard IEC 60331-3 has been prepared by IEC technical committee 20:
Electric cables.
This second edition cancels and replaces the first edition published in 2009. It constitutes a
technical revision.
The significant technical changes with respect to the previous edition are as follows:
– extension of the scope to include metallic data and telecom cables and optical fibre
cables, although details for the specific point of failure, continuity checking arrangement,
test sample, test procedure and test report relevant to metallic data and telecom cables
and optical fibre cables are not given by IEC 60331-3;
– improved description of the test environment;
– mandatory use of mass flow meter/controllers as the means of controlling accurately the
input flow rates of fuel and air to the burner;
– improved description of the information to be included in the test report.
The text of this International Standard is based on the following documents:
FDIS Report on voting
20/1782A/FDIS 20/1794/RVD
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
It has the status of a group safety publication in accordance with IEC Guide 104.
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.
– 6 – IEC 60331-3:2018 © IEC 2018
INTRODUCTION
IEC 60331 consists of the following parts under the general title: Tests for electric cables
under fire conditions – Circuit integrity:
Part 1: Test method for fire with shock at a temperature of at least 830 °C for cables of rated
voltage up to and including 0,6/1,0 kV and with an overall diameter exceeding 20 mm
Part 2: Test method for fire with shock at a temperature of at least 830 °C for cables of rated
voltage up to and including 0,6/1,0 kV and with an overall diameter not exceeding 20 mm
Part 3: Test method for fire with shock at a temperature of at least 830 °C for cables of rated
voltage up to and including 0,6/1,0 kV tested in a metal enclosure
Part 11: Apparatus – Fire alone at a flame temperature of at least 750 °C
Part 21: Procedures and requirements – Cables of rated voltage up to and including
0,6/1,0 kV
Part 23: Procedures and requirements – Electric data cables
Part 25: Procedures and requirements – Optical fibre cables
NOTE 1 Parts 21, 23 and 25 relate to fire-only conditions at a flame temperature of at least 750 °C.
NOTE 2 Parts 11, 21, 23 and 25 are no longer subject to maintenance. IEC 60331 Parts 1 and 2 are the
recommended test procedures
Since its first edition (1970), IEC 60331 has been extended and has introduced a range of test
apparatus in order that a test may be carried out on large and small power, control, data and
optical fibre cables.
IEC 60331-3 introduces apparatus and a procedure to allow cables to be tested in a metal
enclosure under conditions of mechanical shock as well as fire at temperature of at least
830 °C.
TESTS FOR ELECTRIC CABLES UNDER FIRE CONDITIONS –
CIRCUIT INTEGRITY –
Part 3: Test method for fire with shock at a temperature of at least 830 °C
for cables of rated voltage up to and including 0,6/1,0 kV tested
in a metal enclosure
1 Scope
This part of IEC 60331 specifies the test method for cables which are required to maintain
circuit integrity when tested in a metal enclosure and when subject to fire and mechanical
shock under specified conditions.
This document is applicable to cables of rated voltage not exceeding 600 V/1 000 V, including
those of rated voltage below 80 V, metallic data and telecom cables and optical fibre cables.
It is intended for use when testing cables not greater than 20 mm overall diameter.
This document includes details for the specific point of failure, continuity checking
arrangement, test sample, test procedure and test report relevant to electric power and
control cables with rated voltage up to and including 600 V/1 000 V. Details for the specific
point of failure, continuity checking arrangement, test sample, test procedure and test report
relevant to metallic data and telecom cables and optical fibre cables are not given by
IEC 60331-3.
Although the scope is restricted to cables with rated voltage up to and including 0,6/1,0 kV,
the procedure can be used, with the agreement of the manufacturer and the purchaser, for
cables with rated voltage up to and including 1,8/3 (3,3) kV, provided that suitable fuses are
used.
It is not assumed that cables successfully assessed by this method, will also pass
requirements for either IEC 60331-1 or IEC 60331-2. Testing to either of these two standards
is to be carried out separately. Such additional performance can be recognised by the
marking in accordance with IEC 60331-1:2018 Clause 11 or IEC 60331-2:2018 Clause 11.
Annex A provides the method of verification of the burner and control system used for the
test.
CAUTION – The test given in this standard may involve the use of dangerous voltages
and temperatures. Suitable precautions should be taken against the risk of shock,
burning, fire and explosion that may be involved, and against any noxious fumes that
may be produced.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements 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 60269-3, Low-voltage fuses – Part 3: Supplementary requirements for fuses for use by
unskilled persons (fuses mainly for household and similar applications) – Examples of
standardized systems of fuses A to F
– 8 – IEC 60331-3:2018 © IEC 2018
IEC 60331-1:2018, Test for electric cables under fire conditions – Circuit integrity – Part 1:
Test for circuit integrity under conditions of fire with shock at a temperature of at least 830 °C
for cables of rated voltage up to and including 0,6/1,0kV and with an overall diameter
exceeding 20 mm
IEC 60331-2:2018, Test for electric cables under fire conditions – Circuit integrity – Part 2:
Test for circuit integrity under conditions of fire with shock at a temperature of at least 830 °C
for cables of rated voltage up to and including 0,6/1,0kV and with an overall diameter not
exceeding 20 mm
IEC 60584-1, Thermocouples – Part 1: EMF specifications and tolerances
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
circuit integrity
ability of an electric cable to continue to operate in a designated manner whilst subjected to a
specified flame source for a specified period of time under specified conditions
3.2
draught-free environment
space in which the results of tests are not significantly affected by the local air speed
4 Test environment
The test shall be carried out in a draught-free environment within a suitable chamber, of
minimum volume 20 m , with facilities for disposing of any noxious gases resulting from the
burning. Sufficient ventilation shall be available to sustain the flame for the duration of the
test. Air inlets and the exhaust chimney should be located in such a way that the burner flame
remains stable during the verification procedure and test. If necessary, the burner shall be
shielded from any draughts by the use of draught shields. Windows may be installed in the
walls of the chamber in order to observe the behaviour of the cable during the test. Fume
exhaust should be achieved by means of natural draught through a chimney located at least
1 m from the burner. A damper may be used for adjustment of ventilation conditions.
NOTE Experience has shown a chamber similar to the “3 m cube” specified in IEC 61034-1 to be suitable.
The chamber and test apparatus shall be at a temperature of between 10 °C and 40 °C at the
start of each test.
The same ventilation and shielding conditions shall be used in the chamber during both the
verification and cable test procedures.
5 Test apparatus
5.1 Test equipment
The test equipment shall consist of the following:
a) a metal enclosure, through which the test specimen(s) are drawn, constructed from a
straight
...
IEC 60331-3 ®
Edition 2.0 2018-03
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
GROUP SAFETY PUBLICATION
Tests for electric cables under fire conditions – Circuit integrity –
Part 3: Test method for fire with shock at a temperature of at least 830 °C for
cables of rated voltage up to and including 0,6/1,0 kV tested in a metal
enclosure
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.
IEC Central Office Tel.: +41 22 919 02 11
3, rue de Varembé info@iec.ch
CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.
About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigenda or an amendment might have been published.
IEC Catalogue - webstore.iec.ch/catalogue Electropedia - www.electropedia.org
The stand-alone application for consulting the entire The world's leading online dictionary of electronic and
bibliographical information on IEC International Standards, electrical terms containing 21 000 terms and definitions in
Technical Specifications, Technical Reports and other English and French, with equivalent terms in 16 additional
documents. Available for PC, Mac OS, Android Tablets and languages. Also known as the International Electrotechnical
iPad. Vocabulary (IEV) online.
IEC publications search - webstore.iec.ch/advsearchform IEC Glossary - std.iec.ch/glossary
The advanced search enables to find IEC publications by a 67 000 electrotechnical terminology entries in English and
variety of criteria (reference number, text, technical French extracted from the Terms and Definitions clause of
committee,…). It also gives information on projects, replaced IEC publications issued since 2002. Some entries have been
and withdrawn publications. collected from earlier publications of IEC TC 37, 77, 86 and
CISPR.
IEC Just Published - webstore.iec.ch/justpublished
Stay up to date on all new IEC publications. Just Published IEC Customer Service Centre - webstore.iec.ch/csc
details all new publications released. Available online and If you wish to give us your feedback on this publication or
also once a month by email. need further assistance, please contact the Customer Service
Centre: sales@iec.ch.
IEC 60331-3 ®
Edition 2.0 2018-03
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
GROUP SAFETY PUBLICATION
Tests for electric cables under fire conditions – Circuit integrity –
Part 3: Test method for fire with shock at a temperature of at least 830 °C for
cables of rated voltage up to and including 0,6/1,0 kV tested in a metal
enclosure
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 13.220.40; 29.020; 29.060.20 ISBN 978-2-8322-5551-3
– 2 – IEC 60331-3:2018 RLV © IEC 2018
CONTENTS
FOREWORD . 4
INTRODUCTION . 2
1 Scope . 7
2 Normative references . 8
3 Terms and definitions . 8
4 Test conditions – Test environment . 8
5 Test apparatus . 9
5.1 Test equipment . 9
5.2 Metal enclosure . 9
5.2.1 Material and dimensions . 9
5.2.2 Metal enclosure selection . 10
5.3 Test ladder and mounting . 10
5.4 Source of heat . 15
5.4.1 Burner . 15
5.4.2 Flow meters and flow rates . 16
5.4.3 Verification . 17
5.5 Shock-producing device . 17
5.6 Positioning of source of heat . 18
5.7 Continuity checking arrangements for electric power and control cables with
rated voltage up to and including 600 V/1 000 V . 18
5.8 Fuses. 18
6 Test specimen (electric power and control cables with rated voltage up to and
including 600 V/1 000 V) . 18
6.1 Test specimen preparation . 18
6.2 Test specimen mounting . 19
7 Test procedure(electric power and control cables with rated voltage up to and
including 600 V/1 000 V) . 19
7.1 Test equipment and arrangement . 19
7.2 Electrical connections . 19
7.3 Flame and shock application . 21
7.4 Electrification . 21
8 Performance requirements(electric power and control cables with rated voltage up
to and including 600 V/1 000 V) . 22
8.1 Flame application time . 22
8.2 Acceptance criteria . 22
9 Retest procedure . 22
10 Test report (electric power and control cables with rated voltage up to and
including 600 V/1 000 V) . 22
Annex A (normative) Verification procedure for the source of heat . 23
A.1 Measuring equipment . 23
A.2 Procedure . 23
A.3 Evaluation . 24
A.4 Further verification . 24
A.5 Verification report . 24
Annex B (informative) Guidance on the choice of recommended test apparatus (burner
and venturi) . 25
Influence of draughts in the test chamber .
Influence of draughts in the test chamber .
Bibliography . 26
Figure 1 – Schematic diagram of test configuration . 11
Figure 2 – Recommended method of mounting the metal enclosure to the test ladder . 12
Figure 3 – Plan view of fire test equipment . 13
Figure 4 – End elevation of fire test equipment (not to scale) . 14
Figure 5 – Typical rubber bush for supporting the test ladder . 15
Figure 6 – Burner face . 16
Figure 7 – Schematic diagram of an example of a burner control system using
rotameters . 17
Figure 8 – Basic circuit diagram . 21
Figure A.1 – Temperature measuring arrangement . 23
Table 1 – Enclosure dimensions . 9
Table 2 – Multicore sheathed cable . 19
Table 3 – Single core unsheathed or sheathed cable . 19
– 4 – IEC 60331-3:2018 RLV © IEC 2018
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
TESTS FOR ELECTRIC CABLES UNDER FIRE CONDITIONS –
CIRCUIT INTEGRITY –
Part 3: Test method for fire with shock at a temperature of at least 830 °C
for cables of rated voltage up to and including 0,6/1,0 kV tested
in a metal enclosure
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 itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
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.
This redline version of the official IEC Standard allows the user to identify the changes
made to the previous edition. A vertical bar appears in the margin wherever a change
has been made. Additions are in green text, deletions are in strikethrough red text.
International Standard IEC 60331-3 has been prepared by IEC technical committee 20:
Electric cables.
This second edition cancels and replaces the first edition published in 2009. It constitutes a
technical revision.
The significant technical changes with respect to the previous edition are as follows:
– extension of the scope to include metallic data and telecom cables and optical fibre
cables, although details for the specific point of failure, continuity checking arrangement,
test sample, test procedure and test report relevant to metallic data and telecom cables
and optical fibre cables are not given by IEC 60331-3;
– improved description of the test environment;
– mandatory use of mass flow meter/controllers as the means of controlling accurately the
input flow rates of fuel and air to the burner;
– improved description of the information to be included in the test report.
The text of this International Standard is based on the following documents:
FDIS Report on voting
20/1782A/FDIS 20/1794/RVD
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
It has the status of a group safety publication in accordance with IEC Guide 104.
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The “colour inside” logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this publication using a colour printer.
– 6 – IEC 60331-3:2018 RLV © IEC 2018
INTRODUCTION
IEC 60331 consists of the following parts under the general title: Tests for electric cables
under fire conditions – Circuit integrity:
Part 1: Test method for fire with shock at a temperature of at least 830 °C for cables of rated
voltage up to and including 0,6/1,0 kV and with an overall diameter exceeding 20 mm
Part 2: Test method for fire with shock at a temperature of at least 830 °C for cables of rated
voltage up to and including 0,6/1,0 kV and with an overall diameter not exceeding 20 mm
Part 3: Test method for fire with shock at a temperature of at least 830 °C for cables of rated
voltage up to and including 0,6/1,0 kV tested in a metal enclosure
Part 11: Apparatus – Fire alone at a flame temperature of at least 750 °C
Part 21: Procedures and requirements – Cables of rated voltage up to and including
0,6/1,0 kV
Part 23: Procedures and requirements – Electric data cables
Part 25: Procedures and requirements – Optical fibre cables
NOTE 1 Parts 21, 23 and 25 relate to fire-only conditions at a flame temperature of at least 750 °C.
NOTE 2 Parts 11, 21, 23 and 25 are no longer subject to maintenance. IEC 60331 Parts 1 and 2 are the
recommended test procedures
Since its first edition (1970), IEC 60331 has been extended and has introduced a range of test
apparatus in order that a test may be carried out on large and small power, control, data and
optical fibre cables.
IEC 60331-3 introduces apparatus and a procedure to allow cables to be tested in a metal
enclosure under conditions of mechanical shock as well as fire at temperature of at least
830 °C.
TESTS FOR ELECTRIC CABLES UNDER FIRE CONDITIONS –
CIRCUIT INTEGRITY –
Part 3: Test method for fire with shock at a temperature of at least 830 °C
for cables of rated voltage up to and including 0,6/1,0 kV tested
in a metal enclosure
1 Scope
This part of IEC 60331 specifies the test apparatus and procedure and gives the performance
requirements, including recommended flame application times, for low-voltage power cables
of rated voltage up to and including 0,6/1,0 kV, and control cables with a rated voltage which
are required to maintain circuit integrity when tested in a metal enclosure and when subject to
fire and mechanical shock under specified conditions.
This standard describes the means of sample preparation, the continuity checking
arrangements, the electrical testing procedure, the method of burning the cables and the
method of shock production and gives requirements for evaluating test results.
NOTE All cables assessed by this method should first have been assessed against the test of IEC 60331-1 or
IEC 60331-2. Such performance may be recognized by the marking according to Clause 11 of IEC 60331-1 or
Clause 11 of IEC 60331-2.
This part of IEC 60331 specifies the test method for cables which are required to maintain
circuit integrity when tested in a metal enclosure and when subject to fire and mechanical
shock under specified conditions.
This document is applicable to cables of rated voltage not exceeding 600 V/1 000 V, including
those of rated voltage below 80 V, metallic data and telecom cables and optical fibre cables.
It is intended for use when testing cables not greater than 20 mm overall diameter.
This document includes details for the specific point of failure, continuity checking
arrangement, test sample, test procedure and test report relevant to electric power and
control cables with rated voltage up to and including 600 V/1 000 V. Details for the specific
point of failure, continuity checking arrangement, test sample, test procedure and test report
relevant to metallic data and telecom cables and optical fibre cables are not given by
IEC 60331-3.
Although the scope is restricted to cables with rated voltage up to and including 0,6/1,0 kV,
the procedure can be used, with the agreement of the manufacturer and the purchaser, for
cables with rated voltage up to and including 1,8/3 (3,3) kV, provided that suitable fuses are
used.
It is not assumed that cables successfully assessed by this method, will also pass
requirements for either IEC 60331-1 or IEC 60331-2. Testing to either of these two standards
is to be carried out separately. Such additional performance can be recognised by the
marking in accordance with IEC 60331-1:2018 Clause 11 or IEC 60331-2:2018 Clause 11.
Annex A provides the method of verification of the burner and control system used for the
test.
CAUTION – The test given in this standard may involve the use of dangerous voltages
and temperatures. Suitable precautions should be taken against the risk of shock,
– 8 – IEC 60331-3:2018 RLV © IEC 2018
burning, fire and explosion that may be involved, and against any noxious fumes that
may be produced.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements 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 60269-3, Low-voltage fuses – Part 3: Supplementary requirements for fuses for use by
unskilled persons (fuses mainly for household and similar applications) – Examples of
standardized systems of fuses A to F
IEC 60331-1:2018, Test for electric cables under fire conditions – Circuit integrity – Part 1:
Test method for circuit integrity under conditions of fire with shock at a temperature of at least
830 °C for cables of rated voltage up to and including 0,6/1,0kV and with an overall diameter
exceeding 20 mm
IEC 60331-2:2018, Test for electric cables under fire conditions – Circuit integrity – Part 2:
Test method for circuit integrity under conditions of fire with shock at a temperature of at least
830 °C for cables of rated voltage up to and including 0,6/1,0kV and with an overall diameter
not exceeding 20 mm
IEC 60584-1, Thermocouples – Part 1: Reference tables EMF specifications and tolerances
IEC Guide 104, The preparation of safety publications and the use of basic safety publications
and group safety publications
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
circuit integrity
ability of an electric cable to continue to operate in a designated manner whilst subjected to a
specified flame source for a specified period of time under specified conditions
3.2
draught-free environment
space in which the results of tests are not significantly affected by the local air speed
4 Test conditions – Test environment
The test shall be carried out in a draught-free environment within a suitable chamber, of
minimum volume 10 20 m , with facilities for disposing of any noxious gases resulting from
the burning. Sufficient ventilation shall be available to sustain the flame for the duration of the
test. Air inlets and the exhaust chimney should be located in such a way that the burner flame
remains stable during the verification procedure and test. If necessary, the burner shall be
shielded from any draughts by the use of draught shields. Windows may be installed in the
walls of the chamber in order to observe the behaviour of the cable during the test. Fume
exhaust should be achieved by means of natural draught through a chimney located at least
1 m from the burner. A damper may be used for adjustment of ventilation conditions.
NOTE Guidance on the choice of suitable chambers and the need for shielding is given in Annex B.
NOTE Experience has shown a chamber similar to the “3 m cube” specified in IEC 61034-1 to be suitable.
The chamber and test apparatus shall be at a temperature of between 10 °C and 40 °C at the
start of each test.
The same ventilation and shielding conditions shall be used in the chamber during both the
verification and cable test procedures.
NOTE The test given in this standard may involve the use of dangerous voltages and temperatures. Suitable
precautions should be taken against the risk of shock, burning, fire and explosion that may be involved, and
against any noxious fumes that may be produced.
5 Test apparatus
5.1 Test equipment
The test equipment shall consist of the following:
a) a metal enclosure, through which the test specimen(s) are drawn, constructed from a
straight stainless steel tube of circular cross-section as described in 5.2;
b) a test ladder, onto which the metal enclosure is mounted, comprising a steel framework
fastened to a rigid support as described in 5.3;
c) a source of heat comprising a horizontally mounted ribbon burner as described in 5.4;
d) a shock-producing device as described in 5.5;
e) a test wall equipped with thermocouples for verification of the source of heat as described
in Annex A;
f) a continuity checking arrangement as described in 5.7;
g) fuses as described in 5.8.
A general arrangement of the test equipment is shown in Figure 1, Figure 2, Figure 3 and
Figure 4.
5.2 Metal enclosure
5.2.1 Material and dimensions
The enclosure shall comprise a straight stainless steel tube of circular cross-section,
manufactured free from surface irregularities. The metal enclosure shall be (1 300 ± 50) mm
long and shall conform to dimensions as detailed in Table 1.
NOTE 1 Metal conduit as defined in IEC 60614-2-1:1982 has been found to be suitable for the enclosure.
NOTE 2 AISI grades 304 and 316 have been found to be suitable materials for the enclosure.
Table 1 – Enclosure dimensions
Size Wall thickness
mm mm
20 1,6 ± 0,15
40 1,6 ± 0,15
– 10 – IEC 60331-3:2018 RLV © IEC 2018
5.2.2 Metal enclosure selection
The particular metal enclosure shall be selected using the criteria given in 6.2.
5.3 Test ladder and mounting
The test ladder shall consist of a steel framework as shown in Figure 1. The vertical elements
of the ladder shall be fixed at (400 ± 20) mm spacing. The test ladder shall be
(1 200 ± 100) mm long and (600 ± 50) mm high, and the total mass of the test ladder shall be
(18 ± 1) kg. Ballast, if required, shall be placed on the steel supports.
NOTE 1 Angle iron approximately 45 mm wide and 6 mm thick, with suitable slots cut to allow for fixing of the
bolts or saddles, has been found to be a suitable material for construction of the ladder.
The metal enclosure shall be rigidly mounted centrally on the test ladder, as shown
in Figure 2. Suitably sized saddles or U-bolts are recommended for fixing on the vertical
elements.
NOTE 2 It is important that the fixings are tight enough to prevent vertical movement of the metal enclosure whilst
allowing longitudinal expansion of the metal enclosure.
Each horizontal element shall have a mounting hole not more than 200 mm from each end,
the exact position and diameter being determined by the particular supporting bush and
supporting framework used. The test ladder shall be fastened to a rigid support by four
bonded rubber bushes of hardness 50–60 Shore A fitted between the horizontal steel
elements of the ladder and the support framework, as shown in Figure 1 and Figure 3, so as
to allow movement under impact.
NOTE 3 A typical rubber bush, which has been found to be suitable, is shown in Figure 5.
Dimensions in millimetres
1 200 ±100
≈ 400
≈ 400
≈ 400
6 EC
Key
1 shock-producing device 4 ribbon gas burner
2 steel ladder 5 fixed vertical element
3 rubber bush 6 ladder support
Figure 1 – Schematic diagram of test configuration
600 ±50
– 12 – IEC 60331-3:2018 RLV © IEC 2018
Dimensions in millimetres
(dimensions are approximate)
3 3
IEC
Key
1 U-bolt
2 metal enclosure
3 fixed vertical elements
Figure 2 – Recommended method of mounting the metal enclosure
to the test ladder
Dimensions in millimetres
IEC
Key
1 entry for air 4 horizontal steel test ladder
2 rubber bush 5 entry for propane gas
3 support framework
Figure 3 – Plan view of fire test equipment
1 200 ±100
– 14 – IEC 60331-3:2018 RLV © IEC 2018
Dimensions in millimetres
+5
60° 0
200 ±5
400 ±5
600 ±5
H ±2
IEC
Key
1 shock-producing device H horizontal distance of metal enclosure centre line from burner face
2 steel test ladder V vertical distance of metal enclosure centre line from centre line of
burner
3 gas burner
4 centre line of burner face
Figure 4 – End elevation of fire test equipment
(not to scale)
25,0 ±0,1
V ±2
600 ±50
Dimensions in millimetres
30-40
IEC
Figure 5 – Typical rubber bush for supporting the test ladder
5.4 Source of heat
5.4.1 Burner
The source of heat shall be a ribbon type propane gas burner with a nominal burner face
length of 500 mm (outer distance between outer holes) with a venturi mixer. The nominal
burner face width shall be 10 mm. The face of the burner shall have three staggered rows of
drilled holes, nominally 1,32 mm in diameter and drilled at centres 3,2 mm from one another, as
shown in Figure 6.
A centre-feed burner is recommended.
Additionally, A row of small holes milled on each side of the burner plate, to serve as pilot
holes for keeping the flame burning, is permitted.
Guidance on the choice of a recommended burner system is given in Annex B.
20-30
– 16 – IEC 60331-3:2018 RLV © IEC 2018
Dimensions in millimetres
(Dimensions are approximate)
3,2
IEC
NOTE Round holes, 1,32 mm in diameter, on centres 3,2 mm from one another, staggered in three rows and
centred on the face of the burner. Nominal burner face length 500 mm.
Figure 6 – Burner face
5.4.2 Flow meters and flow rates
Mass flow meters/controllers should shall be used as the means of controlling accurately the
input flow rates of fuel and air to the burner.
NOTE Rotameter type flow meters may be used as an alternative, but are not recommended. Guidance on their
use, and the application of appropriate correction factors is given in Annex C of IEC 60331-11:1999.
NOTE Figure 7 shows an example of a rotameter type system.
For the purposes of this test, the air shall have a dew point not higher than 0 °C.
The mass flow rates used for the test shall be as follows:
– air: (160 ± 8) l/min at reference conditions (1 bar and 20 °C) or (3 267 ± 163)
mg/s ;
– propane: (10,0 ± 0,4) l/min at reference conditions (1 bar and 20 °C) or (319 ± 13) mg/s.
Propane: (320 ± 13) mg/s
NOTE 1 This is approximately equivalent to a volume flow rate of (10,0 ± 0,4) litres/min at reference conditions
(1 bar and 20 °C).
NOTE The purity of the propane is not defined. Industrial grades that contain impurities are
allowed, provided that the calibration requirements are achieved.
Air: (3 270 ± 163) mg/s
NOTE 2 This is approximately equivalent to a volume flow rate of (160 ± 8) litres/min at reference conditions
(1 bar and 20 °C).
A schematic diagram of an example of a burner control system is given in Figure 7.
3,2
4,5
6A
IEC
Key
1 regulator 9 mass flow meters
2 piezoelectric igniter 10 venturi mixer
3 flame failure device 11 burner
4 control thermocouples 12 ball valve
5 propane cylinder 13 air flow
6 screw valve (6A = alternative position) 14 compressed air cylinder
7 pilot feed 15 screw valve on pilot feed
8 gas flow
Figure 7 – Schematic diagram of an example of a burner
control system using rotameters
5.4.3 Verification
The burner and control system shall be subject to verification following the procedure given in
Annex A.
5.5 Shock-producing device
The shock-producing device shall consist of a mild steel round bar (25,0 ± 0,1) mm in
diameter and (600 ± 5) mm long. The bar shall be freely pivoted about an axis parallel to the
test ladder, which shall be in the same horizontal plane as, and (200 ± 5) mm away from, the
upper edge of the ladder. The axis shall divide the bar into two unequal lengths, the longer
length being (400 ± 5) mm which shall impact the ladder. The bar shall drop under its own
– 18 – IEC 60331-3:2018 RLV © IEC 2018
+5
weight from an angle of (60 )° to the horizontal to strike the upper edge of the ladder at its
midpoint as shown in Figure 1 and Figure 4.
5.6 Positioning of source of heat
The burner face shall be positioned in the test chamber so that it is at least 200 mm above the
floor of the chamber, or any solid mounting block, and at least 500 mm from any chamber
wall.
By reference to the centre point of the metal enclosure, the burner shall be positioned
centrally at a horizontal distance of (H ± 2) mm from the burner face to the centre of the metal
enclosure and at a vertical distance of (V ± 2) mm from the burner centre line to the centre of
the metal enclosure, as shown in Figure 4.
The exact burner location to be used during cable testing shall be determined using the
verification procedure given in Annex A, where the values of H and V to be used shall be
determined.
NOTE The burner should be rigidly fixed to the framework during testing so as to prevent
movement relative to the metal enclosure.
5.7 Continuity checking arrangements for electric power and control cables with
rated voltage up to and including 600 V/1 000 V
During the test, a current for continuity checking shall be passed through all conductors of the
test specimen(s). This shall be provided by a three-phase star connected or single-phase
transformer(s) of sufficient capacity to maintain the test voltage up to the maximum leakage
current allowable.
NOTE 1 Due Note should be taken of the fuse characteristics when determining the power rating of the
transformer.
This current shall be achieved by connecting, at the other end of the sample specimen, a
suitable load and an indicating device (e.g. lamp) to each conductor, or group of conductors.
NOTE 2 A current of 0,25 A at the test voltage, through each conductor or group of conductors, has been found to
be suitable.
5.8 Fuses
Fuses used in the test procedure in Clause 7 shall be of type DII, complying with IEC 60269-3
Fuse System A-D Type DII, 2A. Alternatively, a circuit-breaker with equivalent characteristics
may be used.
Where a circuit-breaker is used, its equivalent characteristics shall be demonstrated by
reference to the characteristic curve shown in IEC 60269-3.
The test method using fuses shall be the reference method in the case of dispute.
6 Test specimen (electric power and control cables with rated voltage up to
and including 600 V/1 000 V)
6.1 Test specimen preparation
A cable sample at least 15,3 m long for single core, or 5,1 m long for multi-core, shall be
available from the cable length for test. The test specimen to be tested shall consist of either
a single piece of multi-core cable or three pieces of single core cable not less than 1 700 mm
long with approximately 100 mm of sheath or outer covering removed at each end.
At each end of the test specimen, each conductor shall be suitably prepared for electrical
connections, and after being drawn into the appropriate metal enclosure, the exposed
conductors shall be spread apart to avoid contact with each other.
6.2 Test specimen mounting
The test specimen(s) shall be drawn into the appropriate metal enclosure and shall rest on the
wall of the enclosure. The enclosure to be used for a particular cable diameter shall be
selected in accordance with Table 2 for multicore sheathed cable (including multipair and
multi-triple cables), or Table 3 for single core sheathed or unsheathed cable.
Table 2 – Multicore sheathed cable
Cable diameter Metal enclosure size
mm mm
Up to 11,0 20
11,0 to 23,0 40
Table 3 – Single core unsheathed or sheathed cable
Cable diameter Metal enclosure size
mm mm
Up to 6,2 20
6,2 to 13,5 40
The test specimen(s) shall be positioned in the metal enclosure such that it extends outside
the enclosure by greater than 100 mm at each end.
7 Test procedure (electric power and control cables with rated voltage up to
and including 600 V/1 000 V)
7.1 Test equipment and arrangement
The test procedure defined in this clause shall be carried out using the apparatus detailed in
Clause 5.
Draw the test specimen(s) into the metal enclosure and adjust the burner to the correct
position relative to the enclosure in accordance with 5.6.
7.2 Electrical connections
At the transformer end of the test specimen(s), earth the neutral conductor, if present, and
any protective conductors. Any metal screens, drain wire or metallic layer shall be
interconnected and earthed. Connect the transformer(s) to the conductors, excluding any
conductor which is specifically identified as intended for use as a neutral or a protective
conductor, as shown in the circuit diagram in Figure 8. Where a metallic sheath, armour or
screen acts as a neutral or protective conductor, it shall be connected, as shown in the circuit
diagram in Figure 8, as for a neutral or protective conductor. The metal enclosure shall be
earthed.
For single-, twin- or three-phase conductor cables, connect each phase conductor to a
separate phase of the transformer(s) output with a 2 A fuse or circuit-breaker with equivalent
characteristics in each phase. When the test specimen comprises 3 single-core cables, each
single-core test piece shall be considered as a phase conductor.
– 20 – IEC 60331-3:2018 RLV © IEC 2018
For multicore cables that have four or more conductors (excluding any neutral or protective
conductors), the conductors shall be divided into three roughly equal groups, ensuring that
adjacent conductors are, as far as possible, in different groups.
For multipair cables, the conductors shall be divided into two equal groups, ensuring that the
a-core of each pair is connected to one phase and the b-core of each pair is connected to
another phase (L1 and L2 in Figure 8). Quads shall be treated as two pairs.
For multi-triple cables, the conductors shall be divided into three equal groups, ensuring that
the a-core of each triple is connected to one phase, the b-core of each triple to another phase
and the c-core of each triple to the third phase of the transformer (L1, L2 and L3 in Figure 8).
Connect the conductors of each group in series and connect each group to a separate phase
of the transformer output with a 2 A fuse or circuit-breaker with equivalent characteristics in
each phase.
NOTE The above test procedure connects the neutral conductor to earth. This may not be
appropriate if the cable is designed for use on a system where neutral is not earthed. If
required by the cable standard it is permissible for the neutral conductor to be tested as if it
were a phase conductor. Where a metallic sheath, armour or screen acts as a neutral
conductor, it shall always be connected to earth. Any such variations in methodology should
be included in the test report.
NOTE For cable constructions not specifically identified above, the test voltage should be
applied, as far as is practicable, to ensure that adjacent conductors are connected to different
phases.
NOTE In certain cases, for example when testing a control cable using a three-phase
transformer, it may not be possible to apply a test voltage between conductors and from
conductor to earth equal to the rated voltage simultaneously. In such cases, either the test
voltage between conductors, or the test voltage from conductor to earth shall be equal to the
rated voltage, such that both the test voltage between conductors and the test voltage from
conductor to earth is equal to or higher than the rated voltage.
At the end of the sample remote from the transformer:
– connect each phase conductor, or group of conductors, to one terminal of the load and
indicating device (as described in 5.7), the other terminal being earthed;
– connect the neutral conductor and any protective conductor to one terminal of the load
and indicating device (as described in 5.7), the other terminal being connected to L1 (or
L2 or L3) at the transformer end (see Figure 8).
3 5
L1 L1
L2 L2
L3 L3
N
PE
N
7 8
IECI
Key
L1, L2, L3 phase conductor (L2, L3 if present)
N neutral conductor (if present)
PE protective conductor (if present)
1 transformer 5 load and indicating device
2 fuse, 2 A 6 test specimen
3 L1 or L2 or L3 7 metal screen (if present)
8 metal enclosure
4 test conductor or group
Figure 8 – Basic circuit diagram
7.3 Flame and shock application
Ignite the burner and adjust the propane and air flow rates to those obtained during the
verification procedure (see Annex A).
Immediately after igniting the burner, activate the shock-producing device and start the test
duration timer. The shock-producing device shall impact the ladder after 5 min ± 10 s from
activation and subsequently at 5 min ± 10 s intervals. After each impact, the impacting bar
shall be raised from the test ladder no more than 20 s after the impact.
7.4 Electrification
Immediately after starting the test duration timer, switch on the electricity supply and adjust
the voltage to the rated voltage of the sample (subject to a minimum voltage of 100 V AC), i.e.
the test voltage between conductors shall equal the rated voltage between conductors, and
the test voltage from conductor to earth shall equal the rated voltage from conductor to earth.
The test shall continue for the flame application time given in 8.1, after which the flame shall
be extinguished.
– 22 – IEC 60331-3:2018 RLV © IEC 2018
8 Performance requirements (electric power and control cables with rated
voltage up to and including 600 V/1 000 V)
8.1 Flame application time
The flame application time shall be as specified in the relevant cable standard. In the absence
of such a standard, a flame and impact application time of 30 min, 60 min,
...
IEC 60331-3 ®
Edition 2.0 2018-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Tests for electric cables under fire conditions – circuit integrity –
Part 3: Test method for fire with shock at a temperature of at least 830 °C for
cables of rated voltage up to and including 0,6/1,0 kV tested in a metal enclosure
Essais pour câbles électriques soumis au feu – intégrité des circuits –
Partie 3: Méthode d'essai au feu pour les câbles de tension assignée au plus
égale à 0,6/1,0 kV, soumis à essai sous conduit métallique avec chocs, à une
température d'au moins 830 °C
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IEC 60331-3 ®
Edition 2.0 2018-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Tests for electric cables under fire conditions – circuit integrity –
Part 3: Test method for fire with shock at a temperature of at least 830 °C for
cables of rated voltage up to and including 0,6/1,0 kV tested in a metal
enclosure
Essais pour câbles électriques soumis au feu – intégrité des circuits –
Partie 3: Méthode d'essai au feu pour les câbles de tension assignée au plus
égale à 0,6/1,0 kV, soumis à essai sous conduit métallique avec chocs, à une
température d'au moins 830 °C
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.060.20 ISBN 978-2-8322-6152-1
– 2 – IEC 60331-3:2018 © IEC 2018
CONTENTS
CONTENTS . 2
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 8
4 Test environment . 8
5 Test apparatus . 9
5.1 Test equipment . 9
5.2 Metal enclosure . 9
5.2.1 Material and dimensions . 9
5.2.2 Metal enclosure selection . 9
5.3 Test ladder and mounting . 9
5.4 Source of heat . 15
5.4.1 Burner . 15
5.4.2 Flow meters and flow rates . 16
5.4.3 Verification . 17
5.5 Shock-producing device . 18
5.6 Positioning of source of heat . 18
5.7 Continuity checking arrangements for electric power and control cables with
rated voltage up to and including 600 V/1 000 V . 18
5.8 Fuses. 18
6 Test specimen (electric power and control cables with rated voltage up to and
including 600 V/1 000 V) . 19
6.1 Test specimen preparation . 19
6.2 Test specimen mounting . 19
7 Test procedure (electric power and control cables with rated voltage up to and
including 600 V/1 000 V) . 19
7.1 Test equipment and arrangement . 19
7.2 Electrical connections . 20
7.3 Flame and shock application . 21
7.4 Electrification . 21
8 Performance requirements (electric power and control cables with rated voltage
up to and including 600 V/1 000 V) . 22
8.1 Flame application time . 22
8.2 Acceptance criteria . 22
9 Retest procedure . 22
10 Test report (electric power and control cables with rated voltage up to and
including 600 V/1 000 V) . 22
Annex A (normative) Verification procedure for the source of heat . 23
A.1 Measuring equipment . 23
A.2 Procedure . 23
A.3 Evaluation . 24
A.4 Further verification . 24
A.5 Verification report . 24
Annex B (informative) Guidance on the choice of recommended test apparatus (burner
and venturi) . 25
Bibliography . 26
Figure 1 – Schematic diagram of test configuration . 11
Figure 2 – Recommended method of mounting the metal enclosure to the test ladder . 12
Figure 3 – Plan view of fire test equipment . 13
Figure 4 – End elevation of fire test equipment (not to scale) . 14
Figure 5 – Typical rubber bush for supporting the test ladder . 15
Figure 6 – Burner face . 16
Figure 7 – Schematic diagram of an example of a burner control system . 17
Figure 8 – Basic circuit diagram . 21
Figure A.1 – Temperature measuring arrangement . 23
Table 1 – Enclosure dimensions . 9
Table 2 – Multicore sheathed cable . 19
Table 3 – Single core unsheathed or sheathed cable . 19
– 4 – IEC 60331-3:2018 © IEC 2018
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
TESTS FOR ELECTRIC CABLES UNDER FIRE CONDITIONS –
CIRCUIT INTEGRITY –
Part 3: Test method for fire with shock at a temperature of at least 830 °C
for cables of rated voltage up to and including 0,6/1,0 kV tested
in a metal enclosure
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 itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
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.
International Standard IEC 60331-3 has been prepared by IEC technical committee 20:
Electric cables.
This bilingual version (2018-11) corresponds to the monolingual English version, published in
2018-03.
This second edition cancels and replaces the first edition published in 2009. It constitutes a
technical revision.
The significant technical changes with respect to the previous edition are as follows:
– extension of the scope to include metallic data and telecom cables and optical fibre
cables, although details for the specific point of failure, continuity checking arrangement,
test sample, test procedure and test report relevant to metallic data and telecom cables
and optical fibre cables are not given by IEC 60331-3;
– improved description of the test environment;
– mandatory use of mass flow meter/controllers as the means of controlling accurately the
input flow rates of fuel and air to the burner;
– improved description of the information to be included in the test report.
The text of this International Standard is based on the following documents:
FDIS Report on voting
20/1782A/FDIS 20/1794/RVD
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
The French version of this document has not been voted upon.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
It has the status of a group safety publication in accordance with IEC Guide 104.
A list of all parts of the IEC 60331 series, published under the title: Tests for electric cables
under fire conditions – Circuit integrity, can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC website under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
– 6 – IEC 60331-3:2018 © IEC 2018
INTRODUCTION
IEC 60331 consists of the following parts under the general title: Tests for electric cables
under fire conditions – Circuit integrity:
Part 1: Test method for fire with shock at a temperature of at least 830 °C for cables of rated
voltage up to and including 0,6/1,0 kV and with an overall diameter exceeding 20 mm
Part 2: Test method for fire with shock at a temperature of at least 830 °C for cables of rated
voltage up to and including 0,6/1,0 kV and with an overall diameter not exceeding 20 mm
Part 3: Test method for fire with shock at a temperature of at least 830 °C for cables of rated
voltage up to and including 0,6/1,0 kV tested in a metal enclosure
Part 11: Apparatus – Fire alone at a flame temperature of at least 750 °C
Part 21: Procedures and requirements – Cables of rated voltage up to and including
0,6/1,0 kV
Part 23: Procedures and requirements – Electric data cables
Part 25: Procedures and requirements – Optical fibre cables
NOTE 1 Parts 21, 23 and 25 relate to fire-only conditions at a flame temperature of at least 750 °C.
NOTE 2 Parts 11, 21, 23 and 25 are no longer subject to maintenance. IEC 60331 Parts 1 and 2 are the
recommended test procedures.
Since its first edition (1970), IEC 60331 has been extended and has introduced a range of test
apparatus in order that a test may be carried out on large and small power, control, data and
optical fibre cables.
IEC 60331-3 introduces apparatus and a procedure to allow cables to be tested in a metal
enclosure under conditions of mechanical shock as well as fire at temperature of at least
830 °C.
TESTS FOR ELECTRIC CABLES UNDER FIRE CONDITIONS –
CIRCUIT INTEGRITY –
Part 3: Test method for fire with shock at a temperature of at least 830 °C
for cables of rated voltage up to and including 0,6/1,0 kV tested
in a metal enclosure
1 Scope
This part of IEC 60331 specifies the test method for cables which are required to maintain
circuit integrity when tested in a metal enclosure and when subject to fire and mechanical
shock under specified conditions.
This document is applicable to cables of rated voltage not exceeding 600 V/1 000 V, including
those of rated voltage below 80 V, metallic data and telecom cables and optical fibre cables.
It is intended for use when testing cables not greater than 20 mm overall diameter.
This document includes details for the specific point of failure, continuity checking
arrangement, test sample, test procedure and test report relevant to electric power and
control cables with rated voltage up to and including 600 V/1 000 V. Details for the specific
point of failure, continuity checking arrangement, test sample, test procedure and test report
relevant to metallic data and telecom cables and optical fibre cables are not given by
IEC 60331-3.
Although the scope is restricted to cables with rated voltage up to and including 0,6/1,0 kV,
the procedure can be used, with the agreement of the manufacturer and the purchaser, for
cables with rated voltage up to and including 1,8/3 (3,3) kV, provided that suitable fuses are
used.
It is not assumed that cables successfully assessed by this method, will also pass
requirements for either IEC 60331-1 or IEC 60331-2. Testing to either of these two standards
is to be carried out separately. Such additional performance can be recognised by the
marking in accordance with IEC 60331-1:2018 Clause 11 or IEC 60331-2:2018 Clause 11.
Annex A provides the method of verification of the burner and control system used for the
test.
CAUTION – The test given in this standard may involve the use of dangerous voltages
and temperatures. Suitable precautions should be taken against the risk of shock,
burning, fire and explosion that may be involved, and against any noxious fumes that
may be produced.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements 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 60269-3, Low-voltage fuses – Part 3: Supplementary requirements for fuses for use by
unskilled persons (fuses mainly for household and similar applications) – Examples of
standardized systems of fuses A to F
– 8 – IEC 60331-3:2018 © IEC 2018
IEC 60331-1:2018, Test for electric cables under fire conditions – Circuit integrity – Part 1:
Test for circuit integrity under conditions of fire with shock at a temperature of at least 830 °C
for cables of rated voltage up to and including 0,6/1,0kV and with an overall diameter
exceeding 20 mm
IEC 60331-2:2018, Test for electric cables under fire conditions – Circuit integrity – Part 2:
Test for circuit integrity under conditions of fire with shock at a temperature of at least 830 °C
for cables of rated voltage up to and including 0,6/1,0kV and with an overall diameter not
exceeding 20 mm
IEC 60584-1, Thermocouples – Part 1: EMF specifications and tolerances
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
circuit integrity
ability of an electric cable to continue to operate in a designated manner whilst subjected to a
specified flame source for a specified period of time under specified conditions
3.2
draught-free environment
space in which the results of tests are not significantly affected by the local air speed
4 Test environment
The test shall be carried out in a draught-free environment within a suitable chamber, of
minimum volume 20 m , with facilities for disposing of any noxious gases resulting from the
burning. Sufficient ventilation shall be available to sustain the flame for the duration of the
test. Air inlets and the exhaust chimney should be located in such a way that the burner flame
remains stable during the verification procedure and test. If necessary, the burner shall be
shielded from any draughts by the use of draught shields. Windows may be installed in the
walls of the chamber in order to observe the behaviour of the cable during the test. Fume
exhaust should be achieved by means of natural draught through a chimney located at least
1 m from the burner. A damper may be used for adjustment of ventilation conditions.
NOTE Experience has shown a chamber similar to the "3 m cube" specified in IEC 61034-1 to be suitable.
The chamber and test apparatus shall be at a temperature of between 10 °C and 40 °C at the
start of each test.
The same ventilation and shielding conditions shall be used in the chamber during both the
verification and cable test procedures.
5 Test apparatus
5.1 Test equipment
The test equipment shall consist of the following:
a) a metal enclosure, through which the test specimen(s) are drawn, constructed from a
straight stainless steel tube of circular cross-section as described in 5.2;
b) a test ladder, onto which the metal enclosure is mounted, comprising a steel framework
fastened to a rigid support as described in 5.3;
c) a source of heat comprising a horizontally mounted ribbon burner as described in 5.4;
d) a shock-producing device as described in 5.5;
e) a test wall equipped with thermocouples for verification of the source of heat as described
in Annex A;
f) a continuity checking arrangement as described in 5.7;
g) fuses as described in 5.8.
A general arrangement of the test equipment is shown in Figure 1, Figure 2, Figure 3 and
Figure 4.
5.2 Metal enclosure
5.2.1 Material and dimensions
The enclosure shall comprise a straight stainless steel tube of circular cross-section,
manufactured free from surface irregularities. The metal enclosure shall be (1 300 ± 50) mm
long and shall conform to dimensions as detailed in Table 1.
NOTE 1 Metal conduit as defined in IEC 60614-2-1:1982 has been found to be suitable for the enclosure.
NOTE 2 AISI grades 304 and 316 have been found to be suitable materials for the enclosure.
Table 1 – Enclosure dimensions
Size Wall thickness
mm mm
20 1,6 ± 0,15
40 1,6 ± 0,15
5.2.2 Metal enclosure selection
The particular metal enclosure shall be selected using the criteria given in 6.2.
5.3 Test ladder and mounting
The test ladder shall consist of a steel framework as shown in Figure 1. The vertical elements
of the ladder shall be fixed at (400 ± 20) mm spacing. The test ladder shall be
(1 200 ± 100) mm long and (600 ± 50) mm high, and the total mass of the test ladder shall be
(18 ± 1) kg. Ballast, if required, shall be placed on the steel supports.
NOTE 1 Angle iron approximately 45 mm wide and 6 mm thick, with suitable slots cut to allow for fixing of the
bolts or saddles, has been found to be a suitable material for construction of the ladder.
– 10 – IEC 60331-3:2018 © IEC 2018
The metal enclosure shall be rigidly mounted centrally on the test ladder, as shown
in Figure 2. Suitably sized saddles or U-bolts are recommended for fixing on the vertical
elements.
NOTE 2 It is important that the fixings are tight enough to prevent vertical movement of the metal enclosure whilst
allowing longitudinal expansion of the metal enclosure.
Each horizontal element shall have a mounting hole not more than 200 mm from each end,
the exact position and diameter being determined by the particular supporting bush and
supporting framework used. The test ladder shall be fastened to a rigid support by four
bonded rubber bushes of hardness 50–60 Shore A fitted between the horizontal steel
elements of the ladder and the support framework, as shown in Figure 1 and Figure 3, so as
to allow movement under impact.
NOTE 3 A typical rubber bush, which has been found to be suitable, is shown in Figure 5.
Dimensions in millimetres
1 200 ±100
≈ 400
≈ 400
≈ 400
6 IEC
Key
1 shock-producing device 4 ribbon gas burner
2 steel ladder 5 fixed vertical element
3 rubber bush 6 ladder support
Figure 1 – Schematic diagram of test configuration
600 ±50
– 12 – IEC 60331-3:2018 © IEC 2018
Dimensions in millimetres
(dimensions are approximate)
3 3
IEC
Key
1 U-bolt
2 metal enclosure
3 fixed vertical elements
Figure 2 – Recommended method of mounting the metal enclosure
to the test ladder
Dimensions in millimetres
IEC
Key
1 entry for air 4 horizontal steel test ladder
2 rubber bush 5 entry for propane gas
3 support framework
Figure 3 – Plan view of fire test equipment
1 200 ±100
– 14 – IEC 60331-3:2018 © IEC 2018
Dimensions in millimetres
+5
60° 0
200 ±5
400 ±5
600 ±5
H ±2
IEC
Key
1 shock-producing device H horizontal distance of metal enclosure centre line from burner face
2 steel test ladder V vertical distance of metal enclosure centre line from centre line of
burner
3 gas burner
4 centre line of burner face
Figure 4 – End elevation of fire test equipment
(not to scale)
25,0 ±0,1
V ±2
600 ±50
Dimensions in millimetres
30-40
IEC
Figure 5 – Typical rubber bush for supporting the test ladder
5.4 Source of heat
5.4.1 Burner
The source of heat shall be a ribbon type propane gas burner with a nominal burner face
length of 500 mm (outer distance between outer holes) with a venturi mixer. The nominal
burner face width shall be 10 mm. The face of the burner shall have three staggered rows of
drilled holes, nominally 1,32 mm in diameter and drilled at centres 3,2 mm from one another,
as shown in Figure 6.
A centre-feed burner is recommended.
A row of small holes milled on each side of the burner plate, to serve as pilot holes for
keeping the flame burning, is permitted.
Guidance on the choice of a recommended burner system is given in Annex B.
20-30
– 16 – IEC 60331-3:2018 © IEC 2018
Dimensions in millimetres
(Dimensions are approximate)
3,2
IEC
NOTE Round holes, 1,32 mm in diameter, on centres 3,2 mm from one another, staggered in three rows and
centred on the face of the burner. Nominal burner face length 500 mm.
Figure 6 – Burner face
5.4.2 Flow meters and flow rates
Mass flow meters/controllers shall be used as the means of controlling accurately the input
flow rates of fuel and air to the burner.
For the purposes of this test, the air shall have a dew point not higher than 0 °C.
The mass flow rates used for the test shall be as follows:
Propane: (320 ± 13) mg/s
NOTE 1 This is approximately equivalent to a volume flow rate of (10,0 ± 0,4) litres/min at reference conditions
(1 bar and 20 °C).
The purity of the propane is not defined. Industrial grades that contain impurities are allowed
provided that the calibration requirements are achieved.
Air: (3 270 ± 163) mg/s
NOTE 2 This is approximately equivalent to a volume flow rate of (160 ± 8) litres/min at reference conditions
(1 bar and 20 °C).
A schematic diagram of an example of a burner control system is given in Figure 7.
3,2
4,5
6A
1 12
IEC
Key
1 regulator 9 mass flow meters
2 piezoelectric igniter 10 venturi mixer
3 flame failure device 11 burner
4 control thermocouples 12 ball valve
5 propane cylinder 13 air flow
6 screw valve (6A = alternative position) 14 compressed air cylinder
7 pilot feed 15 screw valve on pilot feed
8 gas flow
Figure 7 – Schematic diagram of an example of a burner control system
5.4.3 Verification
The burner and control system shall be subject to verification following the procedure given in
Annex A.
– 18 – IEC 60331-3:2018 © IEC 2018
5.5 Shock-producing device
The shock-producing device shall consist of a mild steel round bar (25,0 ± 0,1) mm in
diameter and (600 ± 5) mm long. The bar shall be freely pivoted about an axis parallel to the
test ladder, which shall be in the same horizontal plane as, and (200 ± 5) mm away from, the
upper edge of the ladder. The axis shall divide the bar into two unequal lengths, the longer
length being (400 ± 5) mm which shall impact the ladder. The bar shall drop under its own
+5
weight from an angle of (60 )° to the horizontal to strike the upper edge of the ladder at its
midpoint as shown in Figure 1 and Figure 4.
5.6 Positioning of source of heat
The burner face shall be positioned in the test chamber so that it is at least 200 mm above the
floor of the chamber, or any solid mounting block, and at least 500 mm from any chamber
wall.
By reference to the centre point of the metal enclosure, the burner shall be positioned
centrally at a horizontal distance of (H ± 2) mm from the burner face to the centre of the metal
enclosure and at a vertical distance of (V ± 2) mm from the burner centre line to the centre of
the metal enclosure, as shown in Figure 4.
The exact burner location to be used during cable testing shall be determined using the
verification procedure given in Annex A, where the values of H and V to be used shall be
determined.
The burner should be rigidly fixed to the framework during testing so as to prevent movement
relative to the metal enclosure.
5.7 Continuity checking arrangements for electric power and control cables with
rated voltage up to and including 600 V/1 000 V
During the test, a current for continuity checking shall be passed through all conductors of the
test specimen(s). This shall be provided by a three-phase star connected or single-phase
transformer(s) of sufficient capacity to maintain the test voltage up to the maximum leakage
current allowable.
NOTE 1 Note the fuse characteristics when determining the power rating of the transformer.
This current shall be achieved by connecting, at the other end of the specimen, a suitable
load and an indicating device (e.g. lamp) to each conductor, or group of conductors.
NOTE 2 A current of 0,25 A at the test voltage, through each conductor or group of conductors, has been found to
be suitable.
5.8 Fuses
Fuses used in the test procedure in Clause 7 shall comply with IEC 60269-3 Fuse System A-D
Type DII, 2A. Alternatively, a circuit-breaker with equivalent characteristics may be used.
Where a circuit-breaker is used, its equivalent characteristics shall be demonstrated by
reference to the characteristic curve shown in IEC 60269-3.
The test method using fuses shall be the reference method in the case of dispute.
6 Test specimen (electric power and control cables with rated voltage up to
and including 600 V/1 000 V)
6.1 Test specimen preparation
A cable sample at least 15,3 m long for single core, or 5,1 m long for multi-core, shall be
available from the cable length for test. The test specimen to be tested shall consist of either
a single piece of multi-core cable or three pieces of single core cable not less than 1 700 mm
long with approximately 100 mm of sheath or outer covering removed at each end.
At each end of the test specimen, each conductor shall be suitably prepared for electrical
connections, and after being drawn into the appropriate metal enclosure, the exposed
conductors shall be spread apart to avoid contact with each other.
6.2 Test specimen mounting
The test specimen(s) shall be drawn into the appropriate metal enclosure and shall rest on the
wall of the enclosure. The enclosure to be used for a particular cable diameter shall be
selected in accordance with Table 2 for multicore sheathed cable (including multipair and
multi-triple cables), or Table 3 for single core sheathed or unsheathed cable.
Table 2 – Multicore sheathed cable
Cable diameter Metal enclosure size
mm mm
Up to 11,0 20
11,0 to 23,0 40
Table 3 – Single core unsheathed or sheathed cable
Cable diameter Metal enclosure size
mm mm
Up to 6,2 20
6,2 to 13,5 40
The test specimen(s) shall be positioned in the metal enclosure such that it extends outside
the enclosure by greater than 100 mm at each end.
7 Test procedure (electric power and control cables with rated voltage up to
and including 600 V/1 000 V)
7.1 Test equipment and arrangement
The test procedure defined in this clause shall be carried out using the apparatus detailed in
Clause 5.
Draw the test specimen(s) into the metal enclosure and adjust the burner to the correct
position relative to the enclosure in accordance with 5.6.
– 20 – IEC 60331-3:2018 © IEC 2018
7.2 Electrical connections
At the transformer end of the test specimen(s), earth the neutral conductor, if present, and
any protective conductors. Any metal screens, drain wire or metal layer shall be
interconnected and earthed. Connect the transformer(s) to the conductors, excluding any
conductor which is specifically identified as intended for use as a neutral or a protective
conductor, as shown in the circuit diagram in Figure 8. Where a metal sheath, armour or
screen acts as a neutral or protective conductor, it shall be connected, as shown in the circuit
diagram in Figure 8, as for a neutral or protective conductor. The metal enclosure shall be
earthed.
For single-, twin- or three-phase conductor cables, connect each phase conductor to a
separate phase of the transformer(s) output with a 2 A fuse or circuit-breaker with equivalent
characteristics in each phase. When the test specimen comprises 3 single-core cables, each
single-core test piece shall be considered as a phase conductor.
For multicore cables that have four or more conductors (excluding any neutral or protective
conductors), the conductors shall be divided into three roughly equal groups, ensuring that
adjacent conductors are, as far as possible, in different groups.
For multipair cables, the conductors shall be divided into two equal groups, ensuring that the
a-core of each pair is connected to one phase and the b-core of each pair is connected to
another phase (L1 and L2 in Figure 8). Quads shall be treated as two pairs.
For multi-triple cables, the conductors shall be divided into three equal groups, ensuring that
the a-core of each triple is connected to one phase, the b-core of each triple to another phase
and the c-core of each triple to the third phase of the transformer (L1, L2 and L3 in Figure 8).
Connect the conductors of each group in series and connect each group to a separate phase
of the transformer output with a 2 A fuse or circuit-breaker with equivalent characteristics in
each phase.
The above test procedure connects the neutral conductor to earth. This may not be
appropriate if the cable is designed for use on a system where neutral is not earthed. If
required by the cable standard it is permissible for the neutral conductor to be tested as if it
were a phase conductor. Where a metal sheath, armour or screen acts as a neutral
conductor, it shall always be connected to earth. Any such variations in methodology should
be included in the test report.
For cable constructions not specifically identified above, the test voltage should be applied, as
far as is practicable, to ensure that adjacent conductors are connected to different phases.
In certain cases, for example when testing a control cable using a three-phase transformer, it
may not be possible to apply a test voltage between conductors and from conductor to earth
equal to the rated voltage simultaneously. In such cases, either the test voltage between
conductors, or the test voltage from conductor to earth shall be equal to the rated voltage,
such that both the test voltage between conductors and the test voltage from conductor to
earth is equal to or higher than the rated voltage.
At the end of the sample remote from the transformer:
– connect each phase conductor, or group of conductors, to one terminal of the load and
indicating device (as described in 5.7), the other terminal being earthed;
– connect the neutral conductor and any protective conductor to one terminal of the load
and indicating device (as described in 5.7), the other terminal being connected to L1 (or
L2 or L3) at the transformer end (see Figure 8).
3 5
L1 L1
L2 L2
L3 L3
N
PE
N
7 8
IEC
Key
L1, L2, L3 phase conductor (L2, L3 if present)
N neutral conductor (if present)
PE protective conductor (if present)
1 transformer 5 load and indicating device
2 fuse, 2 A 6 test specimen
3 L1 or L2 or L3 7 metal screen (if present)
4 test conductor or group 8 metal enclosure
Figure 8 – Basic circuit diagram
7.3 Flame and shock application
Ignite the burner and adjust the propane and air flow rates to those obtained during the
verification procedure (see Annex A).
Immediately after igniting the burner, activate the shock-producing device and start the test
duration timer. The shock-producing device shall impact the ladder after 5 min ± 10 s from
activation and subsequently at 5 min ± 10 s intervals. After each impact, the impacting bar
shall be raised from the test ladder no more than 20 s after the impact.
7.4 Electrification
Immediately after starting the test duration timer, switch on the electricity supply and adjust
the voltage to the rated voltage of the sample (
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