IEC 60331-1:2009
(Main)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
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
IEC 60331-1:2009 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 subject to fire and mechanical shock under specified conditions. It is intended for use when testing cables of greater than 20 mm overall diameter.
NOTE 1 Cables of smaller diameter should be tested using the apparatus, procedure and requirements of IEC 60331-2. This standard describes the means of test specimen 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 2 Although the scope is restricted to cables with rated voltage up to and including 0,6/1,0 kV, the procedure may be used, with the agreement of the manufacturer and the purchaser, for cables with rated voltage up to and including 3,3 kV, provided that suitable fuses are used.
Annex A provides the method of verification of the burner and control system used for the test. Requirements are stated for an identification that may optionally be marked on the cable to signify compliance with this standard. This first edition of IEC 60331-1 cancels and replaces IEC 60331-12 (2002) and IEC 60331-31 (2002) to form one single standard. It has the status of a horizontal standard in accordance with IEC Guide 104.
Essais pour câbles électriques soumis au feu - Intégrité des circuits - Partie 1: Méthode d'essai au feu avec chocs pour les câbles de tension assignée au plus égale à 0,6/1,0 kV et de diamètre externe supérieur à 20 mm, à une température d'au moins 830 °C
La CEI 60331-1:2009 donne des précisions sur l'appareillage et la procédure d'essai et les exigences de performance, y compris des recommandations pour la durée des temps d'application de la flamme pour les câbles de puissance à basse tension, de tension assignée au plus égale à 0,6/1,0 kV, et les câbles de contrôle ayant une tension assignée, qui sont réputés conserver l'intégrité du circuit quand ils sont soumis à un incendie et à des chocs mécaniques dans des conditions spécifiées. Elle est prévue pour être utilisée pour essayer des câbles de diamètre externe supérieur à 20 mm.
NOTE 1 Pour les câbles de diamètre plus petit, il convient d'utiliser l'appareillage, la procédure et les exigences de la CEI 60331-2. Cette norme décrit les moyens de préparation de l'éprouvette d'essai, les dispositions de contrôle de la continuité du circuit, la procédure d'essai électrique, la méthode pour brûler les câbles et la méthode de production des chocs, et indique les exigences pour évaluer les résultats d'essai.
NOTE 2 Bien que le domaine d'application soit limité aux câbles de tension assignée au plus égale à 0,6/1,0 kV, par accord entre client et fournisseur, la procédure peut être utilisée pour des câbles de tension assignée au plus égale à 3,3 kV à condition d'utiliser des fusibles appropriés.
L'Annexe A fournit la méthode de vérification du brûleur et le système de contrôle utilisé pour l'essai. Les conditions requises sont indiquées pour une identification signifiant la conformité à la présente norme par un éventuel marquage sur le câble. Cette première édition de la CEI 60331-1 annule et remplace la CEI 60331-12 (2002) et la CEI 60331-31 (2002) pour établir une seule norme. Elle a le statut de norme horizontale conformément au IEC Guide 104.
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IEC 60331-1 ®
Edition 1.0 2009-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
GROUP SAFETY PUBLICATION
PUBLICATION GROUPÉE DE SÉCURITÉ
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
Essais pour câbles électriques soumis au feu – Intégrité des circuits –
Partie 1: Méthode d’essai au feu avec chocs pour les câbles de tension assignée
au plus égale à 0,6/1,0 kV et de diamètre externe supérieur à 20 mm, à une
température d’au moins 830 °C
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IEC 60331-1 ®
Edition 1.0 2009-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
GROUP SAFETY PUBLICATION
PUBLICATION GROUPÉE DE SÉCURITÉ
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
Essais pour câbles électriques soumis au feu – Intégrité des circuits –
Partie 1: Méthode d’essai au feu avec chocs pour les câbles de tension
assignée au plus égale à 0,6/1,0 kV et de diamètre externe supérieur à 20 mm, à
une température d’au moins 830 °C
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
T
CODE PRIX
ICS 13.220.40; 29.020; 29.060.20 ISBN 978-2-88910-124-5
– 2 – 60331-1 © IEC:2009
CONTENTS
FOREWORD.4
INTRODUCTION.6
1 Scope.7
2 Normative references.7
3 Terms and definitions .8
4 Test conditions – Test environment.8
5 Test apparatus .8
5.1 Test equipment.8
5.2 Test ladder and mounting .12
5.3 Source of heat .12
5.3.1 Burner .12
5.3.2 Flow meters and flow rates .13
5.3.3 Verification .14
5.4 Shock producing device.14
5.5 Positioning of source of heat.15
5.6 Continuity checking arrangements .15
5.7 Fuses .15
6 Test specimen .15
6.1 Test specimen preparation.15
6.2 Test specimen mounting.16
7 Test procedure .17
7.1 Test equipment and arrangement.17
7.2 Electrical connections .17
7.3 Flame and shock application.19
7.4 Electrification.19
8 Performance requirement .20
8.1 Flame application time.20
8.2 Acceptance criteria .20
9 Retest procedure .20
10 Test report.20
11 Cable marking .20
Annex A (normative) Verification procedure for the source of heat .21
Annex B (informative) Guidance on the choice of recommended test apparatus .23
Bibliography .24
Figure 1 – Schematic diagram of test configuration.9
Figure 2 – Plan view of fire test equipment .10
Figure 3 – End elevation of fire test equipment (not to scale) .11
Figure 4 – Typical rubber bush for supporting the test ladder .12
Figure 5 – Burner face .13
Figure 6 – Schematic diagram of an example of a burner control system using
rotameters .14
Figure 7 – Example of method of mounting a larger diameter test specimen for test.16
60331-1 © IEC:2009 – 3 –
Figure 8 – Detailed section of adjustable position of vertical ladder elements for
mounting a smaller diameter test specimen for test .17
Figure 9 – Basic circuit diagram .19
Figure A.1 – Temperature measuring arrangement .21
– 4 – 60331-1 © IEC:2009
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
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
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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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 60331-1 has been prepared by IEC technical committee 20: Electric
cables.
This first edition of IEC 60331-1 cancels and replaces IEC 60331-12 (2002) and IEC 60331-31
(2002) to form one single standard.
The text of this standard is based on the following documents:
FDIS Report on voting
20/1049/FDIS 20/1053/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
60331-1 © IEC:2009 – 5 –
This publication 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 the parts in the IEC 60331 series, under the general 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
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.
– 6 – 60331-1 © IEC:2009
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 Parts 21, 23 and 25 relate to fire-only conditions at a flame temperature of at least 750 °C.
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.
Successful tests carried out in accordance with this standard will enable an identification to be
marked on the product.
60331-1 © IEC:2009 – 7 –
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
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 subject to fire and mechanical shock under specified
conditions. It is intended for use when testing cables of greater than 20 mm overall diameter.
NOTE 1 Cables of smaller diameter should be tested using the apparatus, procedure and requirements of
IEC 60331-2.
This standard describes the means of test specimen 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 2 Although the scope is restricted to cables with rated voltage up to and including 0,6/1,0 kV, the procedure
may be used, with the agreement of the manufacturer and the purchaser, for cables with rated voltage up to and
including 3,3 kV, provided that suitable fuses are used.
Annex A provides the method of verification of the burner and control system used for the test.
Requirements are stated for an identification that may optionally be marked on the cable to
signify compliance with this standard.
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC 60584-1, Thermocouples – Part 1: Reference tables
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 Guide 104, The preparation of safety publications and the use of basic safety publications
and group safety publications
– 8 – 60331-1 © IEC:2009
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
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.
4 Test conditions – Test environment
The test shall be carried out in a suitable chamber, of minimum volume 10 m , with facilities for
disposing of any noxious gases resulting from burning. Sufficient ventilation shall be available
to sustain the flame for the duration of the test.
NOTE 1 Guidance on the choice of suitable chambers is given in Annex B.
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 2 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 test ladder, on to which the test specimen is mounted, comprising a steel framework
fastened to a rigid support as described in 5.2;
b) a source of heat comprising a horizontally mounted ribbon burner as described in 5.3;
c) a shock-producing device as described in 5.4;
d) a test wall equipped with thermocouples for verification of the source of heat as described
in Annex A.
e) a continuity checking arrangement as described in 5.6
f) fuses as described in 5.7
A general arrangement of the test equipment is shown in Figures 1, 2 and 3.
60331-1 © IEC:2009 – 9 –
Dimensions in millimetres
IEC 814/09
Key
1 shock producing device 5 fixed vertical elements of test ladder
2 steel test ladder 6 adjustable vertical elements of test ladder
3 rubber bush 7 RIGID support framework
4 ribbon gas burner P plane of adjustment
Figure 1 – Schematic diagram of test configuration
– 10 – 60331-1 © IEC:2009
Dimensions in millimetres
IEC 815/09
Key
1 entry for air 4 horizontal steel test ladder
2 rubber bush 5 entry for propane gas
3 support framework
Figure 2 – Plan view of fire test equipment
60331-1 © IEC:2009 – 11 –
Dimensions in millimetres
IEC 816/09
Key
1 shock producing device H horizontal distance of metal enclosure centre line from burner face
2 steel test ladder vertical distance of metal enclosure centre line from centre line of burner
V
3 gas burner
4 centre line of burner face
Figure 3 – End elevation of fire test equipment (not to scale)
– 12 – 60331-1 © IEC:2009
5.2 Test ladder and mounting
The test ladder shall consist of a steel framework as shown in Figure 1. The two central vertical
elements of the ladder shall be adjustable in order to accommodate different sizes of cable
under test. 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.
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 Figures 1 and 2 so as to allow movement under
impact.
NOTE 2 A typical rubber bush, which has been found to be suitable, is shown in Figure 4.
Dimensions in millimetres
(dimensions without tolerances are approximate)
IEC 817/09
Figure 4 – Typical rubber bush for supporting the test ladder
5.3 Source of heat
5.3.1 Burner
The source of heat shall be a ribbon type propane gas burner with a nominal burner face length
of 500 mm with a Venturi mixer. A centre-feed burner is recommended. The nominal burner
60331-1 © IEC:2009 – 13 –
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 5. 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.
Dimensions in millimetres
IEC 818/09
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 5 – Burner face
5.3.2 Flow meters and flow rates
Mass flow meters/controllers should be used as the means of controlling accurately the input
flow rates of fuel and air to the burner.
NOTE 1 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 IEC 60331-11:1999, Annex C.
NOTE 2 Figure 6 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 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 ± 0,4) l/min at reference conditions (1 bar and 20 °C) or (319 ± 13) mg/s ;.
NOTE 3 The purity of the propane is not defined. Industrial grades that contain impurities are allowed provided
that the calibration requirements are achieved.
– 14 – 60331-1 © IEC:2009
IEC 819/09
Key
1 regulator 9 flowmeters
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 6 – Schematic diagram of an example of
a burner control system using rotameters
5.3.3 Verification
The burner and control system shall be subject to verification following the procedure given in
Annex A.
5.4 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 weight from an angle
+5
of (60 ) ° to the horizontal to strike the upper edge of the ladder at its midpoint as shown in
Figures 1 and 3.
60331-1 © IEC:2009 – 15 –
5.5 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 test specimen (cable) to be tested, the burner shall be
positioned centrally at a horizontal distance of (H ± 2) mm from the burner face to the centre of
the test specimen and at a vertical distance of (V ± 2) mm from the burner horizontal central
plane to the centre of the test specimen, as shown in Figure 3.
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
test specimen.
5.6 Continuity checking arrangements
During the test, a current for continuity checking shall be passed through all conductors of the
test specimen. 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 test 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.
5.7 Fuses
Fuses used in the test procedure in Clause 7 shall be of type DII, complying with IEC 60269-3.
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
6.1 Test specimen preparation
A cable sample at least 4,5 m long shall be available from the cable length for test. Each
individual test specimen to be tested shall consist of a piece of cable, taken from the cable
sample, not less than 1 500 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 the exposed conductors shall be spread apart to avoid contact with each
other.
– 16 – 60331-1 © IEC:2009
6.2 Test specimen mounting
The test specimen shall be bent to form an approximate arc of a circle. The internal radius of
the bend shall be the manufacturer’s declared minimum bending radius.
The test specimen shall be mounted centrally on the test ladder, as shown in Figure 7, using
metal clips which shall be earthed. Two U-bolts on the upper horizontal element of the ladder
are recommended, but P-clips made of metal strip (20 ± 2) mm wide for cables from 20 mm up
to 50 mm in diameter, and (30 ± 3) mm wide for larger cables shall be used on the central
vertical elements. The P-clips shall be formed so as to have approximately the same diameter
as the test specimen under test.
If the test specimen is too small to be mounted on the central vertical elements when in the
position shown in Figure 7, the vertical elements shall be equally moved towards the centre so
that the specimen may be mounted as shown in Figure 8.
Dimensions in millimetres
(dimensions are approximate)
IEC 820/09
Key
1 U-bolt 5 slot for U-bolt
2 P-clip 6 slot for movement of adjustable vertical elements
3 adjustable vertical elements R minimum bending radius of cable
4 slot for P-clip fixing
Figure 7 – Example of method of mounting a larger diameter test specimen for test
60331-1 © IEC:2009 – 17 –
Dimensions in millimetres
(dimensions are approximate)
IEC 821/09
Key
1 Adjustable position of vertical elements 5 U-bolt
2 Normal position of vertical elements 6 Slot for movement of adjustable vertical
elements
3 Lower horizontal element of test ladder 7 Slot for P-clip fixing
4 Additional clip to maintain cable arc (if required) 8 P-clip
Figure 8 – Detailed section of adjustable position of vertical ladder elements
for mounting a smaller diameter test specimen for test
7 Test procedure
7.1 Test equipment and arrangement
The test procedure shall be carried out using the apparatus detailed in Clause 5.
Mount the test specimen on the test ladder and adjust the burner to the correct position relative
to the test specimen in accordance with 5.5.
7.2 Electrical connections
At the transformer end of the test specimen, earth the neutral conductor 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
– 18 – 60331-1 © IEC:2009
specifically identified as intended for use as a neutral or a protective conductor, as shown in
the circuit diagram in Figure 9. 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 9, as for
a neutral or protective conductor.
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.
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 9). 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 9).
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 1 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 2 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 3 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 test specimen remote from the transformer:
– connect each phase conductor, or group of conductors, to one terminal of the load and
indicating device (as described in 5.6), 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 5.6), the other terminal being connected to L1 (or L2 or
L3) at the transformer end (see Figure 9).
60331-1 © IEC:2009 – 19 –
IEC 822/09
Key
L1, L2, L3 phase conductor (L2, L3 if present)
N neutral conductor (if present)
PE protective conductor (if present)
1 transformer 5 test conductor or group
2 fuse, 2 A 6 load and indicating device
3 L1 or L2 or L3 7 test specimen
4 metal clips 8 metal screen (if present)
Figure 9 – 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 cable (subject to a minimum voltage of 100 V a.c.), 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.
– 20 – 60331-1 © IEC:2009
8 Performance requirement
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, 90 min
or 120 min shall be chosen.
8.2 Acceptance criteria
With reference to the test procedure given in Clause 7, the cable possesses the characteristics
for providing circuit integrity so long as during the course of the test
– the voltage is maintained, i.e. no fuse fails or circuit-breaker is interrupted,
– a conductor does not rupture, i.e. the lamp is not extinguished.
9 Retest procedure
In the event of a failure, as judged by the requirements of the relevant standard, two further
test specimens, taken from the same cable sample, shall be tested. If both comply, the test
shall be deemed successful.
10 Test report
The test report shall include the following information:
a) the number of this standard;
b) a full description of the cable tested;
c) the manufacturer of the cable tested;
d) the test voltage;
e) the actual cable bending radius used for the test;
f) the actual performance requirement applied (by reference to Clause 8);
g) the flame application time;
h) the chamber volume and temperature at the start of the test.
11 Cable marking
If a cable is required to be marked to signify compliance with this standard, it shall be marked
with the number of this standard and the duration of flame application, as follows:
“IEC 60331-1 (XX)” where XX shall be the duration in minutes. The marking shall be in addition
to any requirement of the cable standard.
60331-1 © IEC:2009 – 21 –
Annex A
(normative)
Verification procedure for the source of heat
A.1 Measuring equipment
The flame temperature shall be measured using two 1,5 mm mineral insulated, stainless steel
sheathed thermocouples, type K to IEC 60584-1, mounted on the test wall as shown in
Figure A.1. The thermocouple tips shall be (20,0 ± 1,0) mm in front of the test wall. The
horizontal line of the thermocouples shall be (100 ± 10) mm above the bottom of the wall. The
wall shall consist of a board of heat-resistant, non-combustible and non-metallic material
(900 ± 100) mm long, (300 ± 50) mm high and (10 ± 2) mm thick.
Position the burner 100 mm to 120 mm horizontally from the thermocouple (H) and 40 mm to
60 mm vertically below the centre line of the thermocouples (V) as shown in Figure A.1.
Dimensions in millimetres
(dimensions without tolerances are approximate)
IEC 823/09
Key
1 thermocouple supports
2 thermocouple tip
3 burner
4 1,5 mm type K sheathed thermocouples
H horizontal distance of thermocouple tip from burner face
V vertical distance of thermocouple tip from centre line of burner
Figure A.1 – Temperature measuring arrangement
– 22 – 60331-1 © IEC:2009
A.2 Procedure
Ignite the burner and adjust the gas and air supplies to those given in 5.3.
Monitor the temperature as recorded by the thermocouples over a period of 10 min to ensure
conditions are stable.
A.3 Evaluation
The verification procedure shall be considered satisfactory if:
a) the mean of the averaged readings for each of the two thermocouples over the 10 min falls
+40
within the requirement of (830 )°C and
b) the difference of the averaged readings for each of the two thermocouples over the 10 min
period does not exceed 40 °C.
At least one measurement shall be made every 30 s in order to obtain the average.
NOTE The actual method of obtaining the average thermocouple reading over the period is not specified, but it is
recommended that a recorder with averaging facilities is used in order to damp the variability caused by point
measurement.
If the verification is not successful, the flow rates shall be altered within the tolerances given in
5.3 and a further verification carried out.
A.4 Further verification
If the verification of Clause A.3 is not successful, the distances (H and V) between burner and
thermocouples shall be altered (within the tolerance given in Clause A.1) and a further
verification carried out.
If no successful verification can be achieved within the tolerances given, then the burner
system shall be considered as incapable of providing the source of heat required by this
standard.
A.5 Verification report
The position established for successful verification (H and V) and flow rates used shall be
recorded.
60331-1 © IEC:2009 – 23 –
Annex B
(informative)
Guidance on the choice of recommended test apparatus
B.1 Burner and Venturi
A commercially available burner face meeting the recommendations of this standard is the AGF
burner insert 11-55, and a suitable 500 mm burner, including the specified burner face, is the
AGF, reference 1857B . A recommended Venturi mixer is the AGF 14-18.
The recommended burner and venturi are available from:
Pemfab
30 Indel Avenue
PO Box 227
Rancocas
New Jersey 08073-0227
USA
www.amgasfur.com or www.pemfab.com
B.2 Influence of draughts in the test chamber
Experience has shown that the flame geometry is influenced by any draughts in the test
chamber and it is recommended that the burner be shielded from any draughts by the use of
draught shields.
B.3 Guidance on provision of a suitable test chamber
The chamber shall have a sufficient volume such that fire effluents released during combustion
do not alter the test conditions. Experience has shown a chamber similar to the “3 m cube”
specified in IEC 61034-1 to be suitable, although other chambers of suitable volume may be
used. Windows may be installed in the walls of the chamber in order to observe the behaviour
of the cable during the test. Fume exhaust shoul
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