Tests on electric and optical fibre cables under fire conditions - Part 3-25: Test for vertical flame spread of vertically-mounted bunched wires or cables - Category D

IEC 60332-3-25:2018 is now available as IEC 60332-3-25:2018 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.
IEC 60332-2-25:2018 covers category D for methods of test for the assessment of vertical flame spread of vertically mounted bunched wires or cables, electrical or optical, under defined conditions. This document relates only to small cables of overall diameter 12 mm or smaller and cross-section of 35 mm2 or smaller installed on the test ladder to achieve a nominal total volume of non-metallic material of 0,5 l/m of test sample. The flame application time is 20 min. The method of mounting uses the front of the standard ladder in touching formation only. The category is intended for use with small cables where very low volumes of non-metallic material are required to be evaluated. The test is intended for type approval testing. The requirements for the selection of cables for testing are given in Annex A. The flame spread is measured as the extent of damage of the cable sample. This procedure can be used to demonstrate the cable’s ability to limit flame spread. A recommended performance requirement is given in Annex B. This second edition cancels and replaces the first edition published in 2000 and Amendment 1:2008. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
a) all pre-existing categories of test have been retained and updated;
b) a new category (category D) has been added to cater for testing at very low non-metallic volumes.
It has the status of a group safety publication in accordance with IEC Guide 104.

Essais des câbles électriques et des câbles à fibres optiques soumis au feu - Partie 3-25: Essai de propagation verticale de la flamme des fils ou câbles montés en nappes en position verticale - Catégorie D

IEC 60332-3-25:2018 est disponible sous forme de IEC 60332-3-25:2018 RLV qui contient la Norme internationale et sa version Redline, illustrant les modifications du contenu technique depuis l'édition précédente.
L’IEC 60332-2-25:2018 couvre la catégorie D pour les méthodes d'essai pour l'évaluation de la propagation verticale de la flamme des fils ou câbles, électriques ou optiques, disposés en nappes en position verticale, dans des conditions définie. Le présent document ne concerne que les petits câbles de diamètre extérieur inférieur ou égal à 12 mm et de section inférieure ou égale à 35 mm2 montés sur l’échelle d’essai afin d’obtenir un volume total nominal de matériau non métallique de 0,5 l/m d’échantillon d’essai. La durée d'application de la flamme est de 20 min. La méthode de montage utilise la face avant de l'échelle standard en disposition jointive uniquement. Cette catégorie est prévue pour une utilisation avec des petits câbles lorsqu’il est requis d'évaluer le comportement de volumes très faibles de matériau non métallique. L'essai est prévu pour les essais d'acceptation de type. Les exigences pour la sélection des câbles pour l'acceptation de type sont données à l'Annexe A. La propagation de la flamme est mesurée comme étant l'étendue de la partie endommagée de l'échantillon de câble. Cette procédure peut être utilisée pour démontrer l’aptitude du câble à limiter la propagation de la flamme. L’Annexe B donne une recommandation pour l'exigence de performance. Cette deuxième édition annule et remplace la première édition parue en 2000 et l'Amendement 1:2008. Cette édition constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
a) toutes les catégories déjà existantes de l’essai ont été retenues et mises à jour;
b) une nouvelle catégorie (catégorie D) a été rajoutée afin de satisfaire aux besoins d’essai avec des volumes de matériaux non métalliques très faibles.
Elle a le statut d’une publication groupée de sécurité conformément au Guide IEC 104.

General Information

Status
Published
Publication Date
12-Jul-2018
Technical Committee
Current Stage
PPUB - Publication issued
Completion Date
13-Jul-2018
Ref Project

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IEC 60332-3-25
Edition 2.0 2018-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
GROUP SAFETY PUBLICATION
PUBLICATION GROUPÉE DE SÉCURITÉ
Tests on electric and optical fibre cables under fire conditions –
Part 3-25: Test for vertical flame spread of vertically-mounted bunched wires or
cables – Category D
Essais des câbles électriques et des câbles à fibres optiques soumis au feu –
Partie 3-25: Essai de propagation verticale de la flamme des fils ou câbles
montés en nappes en position verticale – Catégorie D
IEC 60332-3-25:2018-07(en-fr)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC 60332-3-25
Edition 2.0 2018-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
GROUP SAFETY PUBLICATION
PUBLICATION GROUPÉE DE SÉCURITÉ
Tests on electric and optical fibre cables under fire conditions –
Part 3-25: Test for vertical flame spread of vertically-mounted bunched wires or
cables – Category D
Essais des câbles électriques et des câbles à fibres optiques soumis au feu –
Partie 3-25: Essai de propagation verticale de la flamme des fils ou câbles
montés en nappes en position verticale – Catégorie D
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 13.220.40; 29.060.20 ISBN 978-2-8322-5794-4

Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 3 ----------------------
– 2 – IEC 60332-3-25:2018 © IEC 2018
CONTENTS

FOREWORD ........................................................................................................................3

INTRODUCTION ..................................................................................................................5

1 Scope ...........................................................................................................................6

2 Normative references ....................................................................................................6

3 Terms and definitions ....................................................................................................6

4 Test apparatus ..............................................................................................................7

4.1 General ................................................................................................................7

4.2 Ignition source ......................................................................................................7

5 Test procedure ..............................................................................................................7

5.1 Test sample ..........................................................................................................7

5.2 Determination of the number of test pieces ............................................................7

5.3 Mounting of the test sample ..................................................................................8

5.4 Flame application time ..........................................................................................9

6 Evaluation of test results ...............................................................................................9

7 Performance requirements .............................................................................................9

8 Retest procedure ...........................................................................................................9

9 Test report ....................................................................................................................9

Annex A (normative) Guidance on cable selection for type approval testing ........................ 11

Annex B (informative) Recommended performance requirements ....................................... 12

Bibliography ....................................................................................................................... 13

Figure 1 – Touching cables mounted on the front side of the standard ladder (arrays of

cables in contact) ............................................................................................................... 10

Table A.1 – Summary of test conditions .............................................................................. 11

---------------------- Page: 4 ----------------------
IEC 60332-3-25:2018 © IEC 2018 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
TESTS ON ELECTRIC AND OPTICAL FIBRE
CABLES UNDER FIRE CONDITIONS –
Part 3-25: Test for vertical flame spread of
vertically-mounted bunched wires or cables – Category D
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,

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Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested

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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

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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 60332-3-25 has been prepared by IEC technical committee 20:

Electric cables.
This second edition cancels and replaces the first edition published in 2000 and
Amendment 1:2008. This edition constitutes a technical revision.

This edition includes the following significant technical changes with respect to the previous

edition:

a) adjustments have been made to the title, and elsewhere, to emphasise the standard is

applicable to optical fibre cables as well as metallic conductor types;

b) details of the way in which cables are mounted on the ladder have been better defined in

order to improve repeatability and reproducibility.
---------------------- Page: 5 ----------------------
– 4 – IEC 60332-3-25:2018 © IEC 2018

It has the status of a group safety publication in accordance with IEC Guide 104.

The text of this International Standard is based on the following documents:
FDIS Report on voting
20/1802/FDIS 20/1819/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.

A list of all parts in the IEC 60332 series, published under the general title Tests on electric

and optical fibre cables under fire conditions, can be found on the IEC website.

Future standards in this series will carry the new general title as cited above. Titles of

existing standards in this series will be updated at the time of the next edition.

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.
---------------------- Page: 6 ----------------------
IEC 60332-3-25:2018 © IEC 2018 – 5 –
INTRODUCTION

IEC 60332-3-25 is part of a series of publications dealing with tests on electric and optical

fibre cables under fire conditions.
The IEC 60332-1 and IEC 60332-2 series specify methods of test for flame spread

characteristics for a single vertical insulated wire or cable. It cannot be assumed that,

because a cable or wire meets the requirements of the IEC 60332-1 and IEC 60332-2 series,

a vertical bunch of similar cables or wires will behave in a similar manner. This is because

flame spread along a vertical bunch of cables depends on a number of features, such as

a) the volume of combustible material exposed to the fire and to any flame which may be

produced by the combustion of the cables;

b) the geometrical configuration of the cables and their relationship to an enclosure;

c) the temperature at which it is possible to ignite the gases emitted from the cables;

d) the quantity of combustible gas released from the cables for a given temperature rise;

e) the volume of air passing through the cable installation;

f) the construction of the cable, for example armoured or unarmoured, multi- or single-core.

All of the foregoing assume that the cables are able to be ignited when involved in an

external fire.

The IEC 60332-3 series gives details of a test where a number of cables are bunched

together to form various test sample installations. For easier use and differentiation of the

various test categories, the parts are designated as follows:
Part 3-10: Apparatus
Part 3-21: Category A F/R
Part 3-22: Category A
Part 3-23: Category B
Part 3-24: Category C
Part 3-25: Category D

Parts from 3-21 onwards define the various categories and the relevant procedures. The

categories are distinguished by test duration, the volume of non-metallic material of the test

sample and the method of mounting the sample for the test. In all categories, cables having

at least one conductor of cross-sectional area greater than 35 mm are tested in a spaced

configuration, whereas cables of conductor cross-sectional area of 35 mm or smaller and

optical fibre cables are tested in a touching configuration.

The categories are not necessarily related to different safety levels in actual cable

installations. The actual installed configuration of the cables may be a major determinant in

the level of flame spread occurring in an actual fire.

The method of mounting described as category A F/R (Part 3-21) is intended for special cable

designs used in particular installations.

Categories A, B, C and D (Part 3-22 to Part 3-25 respectively) are for general use where

different non-metallic volumes are applicable.
---------------------- Page: 7 ----------------------
– 6 – IEC 60332-3-25:2018 © IEC 2018
TESTS ON ELECTRIC AND OPTICAL FIBRE
CABLES UNDER FIRE CONDITIONS –
Part 3-25: Test for vertical flame spread of
vertically-mounted bunched wires or cables – Category D
1 Scope

This part of IEC 60332 covers category D for methods of test for the assessment of vertical

flame spread of vertically mounted bunched wires or cables, electrical or optical, under

defined conditions.

This document relates only to small cables of overall diameter 12 mm or smaller and cross-

section of 35 mm or smaller installed on the test ladder to achieve a nominal total volume of

non-metallic material of 0,5 l/m of test sample. The flame application time is 20 min. The

method of mounting uses the front of the standard ladder in touching formation only. The

category is intended for use with small cables where very low volumes of non-metallic

material are required to be evaluated.

The test is intended for type approval testing. The requirements for the selection of cables for

testing are given in Annex A. The flame spread is measured as the extent of damage of the

cable sample. This procedure can be used to demonstrate the cable’s ability to limit flame

spread.
A recommended performance requirement is given in Annex B.

NOTE For the purposes of this document the term "electric wire or cable" covers all insulated metallic conductor

cables used for the conveyance of energy or signals.
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 60332-3-10, Tests on electric and optical fibre cables under fire conditions – Part 3-10:

Test for vertical flame spread of vertically-mounted bunched wires or cables – Apparatus

IEC 60811-606, Electric and optical fibre cables – Test methods for non-metallic materials –

Part 606: Physical tests – Methods for determining the density
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
---------------------- Page: 8 ----------------------
IEC 60332-3-25:2018 © IEC 2018 – 7 –
3.1
ignition source
source of energy that initiates combustion
[SOURCE: ISO 13943:2017, 3.219]
3.2
char
carbonaceous residue resulting from pyrolysis or incomplete combustion
[SOURCE: ISO 13943:2017, 3.47]
3.3
flame spread
propagation of a flame front
[SOURCE: ISO 13943:2017, 3.168]
4 Test apparatus
4.1 General
The apparatus specified in IEC 60332-3-10 shall be used.
4.2 Ignition source
The ignition source shall be one ribbon-type propane gas burner as specified in
IEC 60332-3-10.
5 Test procedure
5.1 Test sample

The test sample shall comprise a number of test pieces of cable from the same production

length, each having a minimum length of 3,5 m.

The total number of test pieces in the test sample shall be that number required to provide a

nominal total volume of non-metallic material of 0,5 l/m of test sample.
The test sample for type approval shall be in accordance with Annex A.

The test pieces forming the test sample shall be conditioned at a temperature of (20 ± 10) °C

for at least 16 h before commencing the test. The test pieces shall be dry.
5.2 Determination of the number of test pieces

In order to calculate the appropriate number of test pieces, it is necessary to determine the

volume per metre of non-metallic material of one test piece.

A length of cable which shall be not less than 0,3 m long is carefully cut to ensure that the

surfaces are at right angles to the cable axis, thus enabling precise measurements of its length.

The density of each non-metallic component (including cellular material) shall be measured in

an appropriate way, for example according to IEC 60811-606, in order to obtain values

expressed to the second decimal place.
---------------------- Page: 9 ----------------------
– 8 – IEC 60332-3-25:2018 © IEC 2018

Each non-metallic material C shall be removed from the test piece and weighed. Any non-

metallic material making up less than 5 % of the total non-metallic mass of the test piece

shall be assumed to have a density of 1,0 kg/dm .

Where semi-conducting screens cannot be removed from the insulating material, the

components may be considered as one for the purpose of measuring their mass and density.

The volume V (litres per metre of cable) of each non-metallic material C is calculated as

i i
follows:
V =
ρ ×l
where
M is the mass of the component C (kg);
i i
ρ is the density of the component C (kg/dm );
i i
l is the length of the test piece of cable (m).

The total volume, V, of the non-metallic materials contained in 1 m of cable is equal to the

sum of the individual volumes V , V , etc.
1 2

The number of test pieces to be mounted is obtained by taking the closest integer (0,5 and

above corresponding to 1) of the ratio of the volume per metre specified in 5.1 and the total

volume, V, of non-metallic material per metre of cable, subject to a minimum number of two

test pieces.
5.3 Mounting of the test sample

Each test piece shall be attached, either individually or as part of an array, to each rung of

the ladder by means of metal wire (steel or copper) between 0,5 mm and 1,0 mm in diameter.

Test pieces shall be attached to the front of the standard ladder in touching formation in one

or more layers up to a maximum total width of 300 mm. There shall be a minimum distance of

50 mm between the edge of the test sample and the inside of the ladder uprights.

When mounting the test pieces, the first test piece or array of test pieces shall be positioned

approximately in the centre of the ladder and further test pieces or arrays added on either

side so that the test sample is approximately centred on the ladder.

Mount all test pieces on the ladder with the bending (due to bending of the cable on the reel),

if any, in the same direction, towards the back side of the test chamber as much as possible.

To achieve straight test pieces between the steel rungs below and above the burner position,

it is permitted to fix the test pieces to an additional horizontal support 200 mm to 300 mm

lower than the steel rung below the burner position.

In order to ensure that the test pieces are straight on the ladder, the test pieces shall be

maintained under tension manually while attaching the test pieces to the rung of the ladder

by means of a metal wire.

NOTE The objective is to improve the repeatability and reproducibility of the test.

If a second (or more) layer of test pieces is required after the full width of the ladder has

been utilized for the first (or following) layer, then the first test piece or array of test pieces in

the second (or following) layer shall be positioned approximately in the centre of the ladder

---------------------- Page: 10 ----------------------
IEC 60332-3-25:2018 © IEC 2018 – 9 –

and further test pieces or arrays added on either side so that the second (or following) layer

is approximately centred on the ladder.

If a large number of test pieces is required to make up a test sample, the test pieces may be

attached to each rung of the ladder in flat arrays of cables of a maximum width of five test

pieces using the specified metal wire. For consistency, it is recommended that adjacent

arrays of cables are secured together at every rung to ensure that they are in touching

formation (see Figure 1).
5.4 Flame application time

The test flame shall be applied for 20 min, after which it shall be extinguished. The air flow

rate through the test chamber shall be maintained until cable burning or glowing has ceased,

or until a maximum duration of 1 h, after which any remaining cable burning or glowing shall

be extinguished.
6 Evaluation of test results

After all cable burning or glowing has ceased or been extinguished, the test sample shall be

wiped clean.

All soot is to be ignored if, when wiped off, the original surface is undamaged. Softening or

any deformation of the non-metallic material is also to be ignored. The flame spread shall be

measured as the extent of the damage. It shall be measured in metres to two decimal places

from the bottom edge of the burner to the onset of char. The onset of char is determined as

follows:

press against the cable surface with a sharp object, for example a knife blade. Where the

surface changes from a resilient to a brittle (crumbling) surface, this indicates the onset

of char.
7 Performance requirements

The performance requirements for a particular type or class of wire or cable should preferably

be given in the individual cable standard. In the absence of any given requirements, the

recommended performance requirements on given in Annex B should be used.
8 Retest procedure

In case of a disputed failure, two further tests shall be undertaken as detailed in Clause 5.

The test shall be deemed as satisfactory if both tests meet the stated requirement.

9 Test report
The test report shall include the following information:
a) full description of the cable tested;
b) manufacturer of the cable tested;
c) the part of the standard against which the test was carried out;
d) the number of test pieces;

e) the total volume of non-metallic material, per metre of test sample, of the test pieces;

f) the method of mounting (i.e. touching);
g) the number of layers and the number of test pieces in each layer;
---------------------- Page: 11 ----------------------
– 10 – IEC 60332-3-25:2018 © IEC 2018
h) flame application time (i.e. 20 min);
i) the number of burners (i.e. one);
j) the extent of damage;
k) the time to extinction of all burning or glowing.
Dimensions in millimetres
Key
1 centre line of the ladder
Figure 1 – Touching cables mounted on the front side of the standard ladder
(arrays of cables in contact)
---------------------- Page: 12 ----------------------
IEC 60332-3-25:2018 © IEC 2018 – 11 –
Annex A
(normative)
Guidance on cable selection for type approval testing

The choice of cable type and conductor cross-section for type approval testing shall be as

given in the cable specification, or as agreed between purchaser and manufacturer.

The limited capacity of the ladders requires consideration of the conductor cross-section

selected for testing to ensure that the volume of non-metallic material can be accommodated

within the specified method of mounting. Therefore the selection of cables for this document

shall comply with the following:
• only the front face of the ladder shall be used;
• the minimum number of test pieces in each layer shall be two;
• there are no other restrictions on the selection of cables.

A summary of all conditions for type approval testing to this document is given in Table A.1.

Table A.1 – Summary of test conditions
Category and designation D
Non-metallic volume per metre of test sample (l) 0,5
Use of standard ladder, maximum width of test sample:
300 mm
– number of layers: ≥ 1
– number of burners: 1
Positioning of test pieces Touching
Flame application time (min) 20
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