Fire hazard testing - Part 2-12: Glowing/hot-wire based test methods - Glow-wire flammability index (GWFI) test method for materials

IEC 60695-2-12:2021 is available as IEC 60695-2-12:2021 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.
IEC 60695-2-12:2021 specifies the details of the glow-wire test to be applied to test specimens of solid electrical insulating materials or other solid materials for flammability testing to determine the glow-wire flammability index (GWFI). GWFI is the highest temperature, determined during this standardized procedure, at which the tested material does not ignite or, if it does, extinguishes within 30 s after removal of the glow-wire and is not totally consumed; and molten drips, if they occur, do not ignite the wrapping tissue. This test method is a materials test carried out on a series of standard test specimens. The data obtained, along with data from the glow-wire ignition temperature (GWIT) test method for materials, IEC 60695-2-13, can then be used in a preselection process in accordance with IEC 60695-1-30 [4] to judge the ability of materials to meet the requirements of IEC 60695-2-11. This basic safety publication focusing on safety test method(s) is primarily intended for use by technical committees in the preparation of safety publications in accordance with the principles laid down in IEC Guide 104 and ISO/IEC Guide 51. One of the responsibilities of a technical committee is, wherever applicable, to make use of basic safety publications in the preparation of its publications. This publication is to be read in conjunction with IEC 60695-2-10. This third edition cancels and replaces the second edition published in 2010 and Amendment 1:2014. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
a) New terms and definitions with regards to times and durations have been added to Clause 3, with an effect on the application of the test method.

Essais relatifs aux risques du feu - Partie 2-12: Essais au fil incandescent/chauffant - Méthode d'essai d'indice d'inflammabilité au fil incandescent (GWFI) pour matériaux

IEC 60695-2-12:2021 est disponible sous forme de IEC 60695-2-12:2021 RLV qui contient la Norme internationale et sa version Redline, illustrant les modifications du contenu technique depuis l'édition précédente.
IEC 60695-2-12:2021 décrit les informations détaillées de l’essai au fil incandescent destiné à être appliqué à des éprouvettes d’essai de matériaux isolants électriques solides ou autres matériaux solides pour les essais d’inflammabilité dans le but de déterminer l’indice d’inflammabilité au fil incandescent (GWFI, glow-wire flammability index). Le GWFI est la température la plus élevée, déterminée durant cette procédure normalisée, à laquelle le matériau en essai ne s’enflamme pas ou s’il s’enflamme, s’éteint dans les 30 s qui suivent le retrait du fil incandescent et n’est pas entièrement consumé; et des gouttes en fusion, s’il y a lieu, n’enflamment pas le papier mousseline. Cette méthode d’essai est un essai de matériaux exécuté sur une série d’éprouvettes d'essai normalisées. Les données obtenues, ainsi que les données issues de la méthode d’essai de température d’allumabilité au fil incandescent (GWIT, glow-wire ignition temperature) pour matériaux, IEC 60695-2-13, peuvent alors être utilisées dans un processus de présélection conformément à l’IEC 60695 1 30 [4] pour estimer l'aptitude des matériaux à satisfaire aux exigences de l’IEC 60695 2 11. La présente publication fondamentale de sécurité, fondée sur la ou les méthodes d'essai de sécurité, est essentiellement destinée à être utilisée par les comités d’études dans le cadre de l’élaboration de publications de sécurité conformément aux principes établis dans le Guide IEC 104 et le Guide ISO/IEC 51. L’une des responsabilités d’un comité d’études consiste, le cas échéant, à utiliser les publications fondamentales de sécurité dans le cadre de l’élaboration de ses publications. Cette norme doit être utilisée conjointement avec l’IEC 60695-2-10. Cette troisième édition annule et remplace la deuxième édition parue en 2010 et l'Amendement 1:2014. Cette édition constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
a) ajout à l’Article 3 de nouveaux termes et définitions, ayant rapport aux moments et durées, applicables à la méthode d'essai.

General Information

Status
Published
Publication Date
07-Oct-2021
Technical Committee
Current Stage
PPUB - Publication issued
Completion Date
08-Oct-2021
Ref Project

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IEC 60695-2-12
Edition 3.0 2021-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
HORIZONTAL PUBLICATION
PUBLICATION HORIZONTALE
Fire hazard testing –
Part 2-12: Glowing/hot-wire based test methods – Glow-wire flammability index
(GWFI) test method for materials
Essais relatifs aux risques du feu –
Partie 2-12: Essais au fil incandescent/chauffant – Méthode d'essai d'indice
d’inflammabilité au fil incandescent (GWFI) pour matériaux
IEC 60695-2-12:2021-10(en-fr)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC 60695-2-12
Edition 3.0 2021-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
HORIZONTAL PUBLICATION
PUBLICATION HORIZONTALE
Fire hazard testing –
Part 2-12: Glowing/hot-wire based test methods – Glow-wire flammability index
(GWFI) test method for materials
Essais relatifs aux risques du feu –
Partie 2-12: Essais au fil incandescent/chauffant – Méthode d'essai d'indice
d’inflammabilité au fil incandescent (GWFI) pour matériaux
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 13.220.40; 29.020 ISBN 978-2-8322-1011-1

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 60695-2-12:2021 © IEC 2021
CONTENTS

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

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

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

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

3 Terms and definitions ...................................................................................................... 7

4 Test specimens ............................................................................................................... 8

4.1 Test specimen preparation ...................................................................................... 8

4.2 Test specimen dimensions ...................................................................................... 8

4.3 Testing ranges in formulations ................................................................................ 9

4.3.1 General ........................................................................................................... 9

4.3.2 Density, melt flows and filler/reinforcement ...................................................... 9

4.3.3 Colour ............................................................................................................. 9

5 Apparatus ........................................................................................................................ 9

6 Temperature measuring system verification ..................................................................... 9

7 Conditioning and test conditions ...................................................................................... 9

7.1 Conditioning of test specimens ............................................................................... 9

7.2 Conditioning of the wrapping tissue and the wooden board ................................... 10

7.3 Testing conditions ................................................................................................. 10

8 Test procedure .............................................................................................................. 10

8.1 General ................................................................................................................. 10

8.2 Initial test temperatures ........................................................................................ 10

8.3 Test temperatures ................................................................................................. 10

9 Observations and measurements ................................................................................... 11

9.1 Initial observations ................................................................................................ 11

9.2 Test observations ................................................................................................. 11

10 Evaluation of test results ............................................................................................... 11

10.1 Test criteria .......................................................................................................... 11

10.2 Glow-wire flammability index ................................................................................. 12

11 Test report ..................................................................................................................... 12

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

Table 1 – Initial test temperatures ......................................................................................... 10

---------------------- Page: 4 ----------------------
IEC 60695-2-12:2021 © IEC 2021 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FIRE HAZARD TESTING –
Part 2-12: Glowing/hot-wire based test methods –
Glow-wire flammability index (GWFI) test method for materials
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

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between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in

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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.

IEC 60695-2-12 has been prepared by IEC technical committee 89: Fire hazard testing. It is

an International Standard.
This third edition cancels and replaces the second edition published in 2010 and
Amendment 1:2014. This edition constitutes a technical revision.

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

edition:

a) New terms and definitions with regards to times and durations have been added to

Clause 3, with an effect on the application of the test method.
---------------------- Page: 5 ----------------------
– 4 – IEC 60695-2-12:2021 © IEC 2021
The text of this International Standard is based on the following documents:
FDIS Report on voting
89/1537/FDIS 89/1545/RVD

Full information on the voting for its approval can be found in the report on voting indicated in

the above table.
The language used for the development of this International Standard is English.

This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in

accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement,

available at www.iec.ch/members_experts/refdocs. The main document types developed by

IEC are described in greater detail at www.iec.ch/standardsdev/publications.

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

This standard is to be used in conjunction with IEC 60695-2-10.

A list of all the parts in the IEC 60695 series, under the general title Fire hazard testing, can

be found on the IEC web site.

The committee has decided that the contents of this document will remain unchanged until the

stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to

the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
---------------------- Page: 6 ----------------------
IEC 60695-2-12:2021 © IEC 2021 – 5 –
INTRODUCTION

In the design of any electrotechnical product, the risk of fire and the potential hazards

associated with fire need to be considered. In this respect the objective of component, circuit,

and product design, as well as the choice of materials, is to reduce to acceptable levels the

potential risks of fire during normal operating conditions, reasonable foreseeable abnormal

use, malfunction and/or failure. IEC 60695-1-10 [1] , together with its companion

IEC 60695-1-11 [2], has been developed to provide guidance on how this is to be
accomplished.

The primary aims of IEC 60695-1-10 and IEC 60695-1-11 are to provide guidance on how to:

a) prevent ignition caused by an electrically energized component part, and

b) confine any resulting fire within the bounds of the enclosure of the electrotechnical

product in the event of ignition.

Secondary aims of IEC 60695-1-10 and IEC 60695-1-11 include the minimization of any flame

spread beyond the product’s enclosure and the minimization of the harmful effects of fire

effluents such as heat, smoke, toxicity and/or corrosivity.

Fires involving electrotechnical products can also be initiated from external non-electrical

sources. Considerations of this nature are normally dealt with in the overall fire hazard

assessment.

In electrotechnical equipment, overheated metal parts can act as ignition sources. In glow-

wire tests, a glowing wire is used to simulate such an ignition source.
IEC 60695-2-10 describes a glow-wire test apparatus and common test procedure,
IEC 60695-2-11 [3] describes a glow-wire flammability test for end products, and

IEC 60695-2-13 describes a glow-wire ignition temperature (GWIT) test method for materials.

This document describes a glow-wire flammability index test for materials. It is intended to be

used to measure, describe, and rank the properties of materials in response to heat caused

by contact with an electrically heated wire under controlled laboratory conditions. This may be

useful for the evaluation of materials for use in products that may be exposed to excess

thermal stress such as a fault current flowing through a wire, overloading of components, and/or bad

connections. It is not intended to be used to solely describe or appraise the fire hazard or fire

risk of materials, products, or assemblies under actual fire conditions. However, results of this

test can be used as elements of a fire hazard assessment which takes into account all of the

factors which are pertinent to a particular end use.

This document may involve hazardous materials, operations, and equipment. It does not

purport to address all of the safety problems associated with its use. It is the responsibility of

the user of this document to establish appropriate safety and health practices and determine

the applicability of regulatory limitations prior to use.
___________
Numbers in square brackets refer to the bibliography.
---------------------- Page: 7 ----------------------
– 6 – IEC 60695-2-12:2021 © IEC 2021
FIRE HAZARD TESTING –
Part 2-12: Glowing/hot-wire based test methods –
Glow-wire flammability index (GWFI) test method for materials
1 Scope

This part of IEC 60695 specifies the details of the glow-wire test to be applied to test

specimens of solid electrical insulating materials or other solid materials for flammability

testing to determine the glow-wire flammability index (GWFI).

GWFI is the highest temperature, determined during this standardized procedure, at which the

tested material does not ignite or, if it does, extinguishes within 30 s after removal of the

glow-wire and is not totally consumed; and molten drips, if they occur, do not ignite the

wrapping tissue.

This test method is a materials test carried out on a series of standard test specimens. The

data obtained, along with data from the glow-wire ignition temperature (GWIT) test method for

materials, IEC 60695-2-13, can then be used in a preselection process in accordance with

IEC 60695-1-30 [4] to judge the ability of materials to meet the requirements of
IEC 60695-2-11.

NOTE As an outcome of conducting a fire hazard assessment, an appropriate series of preselection flammability

and ignition tests can allow a reduction of end product testing.

This basic safety publication focusing on safety test method(s) is primarily intended for use by

technical committees in the preparation of safety publications in accordance with the

principles laid down in IEC Guide 104 and ISO/IEC Guide 51.

One of the responsibilities of a technical committee is, wherever applicable, to make use of

basic safety publications in the preparation of its publications.
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 60695-2-10, Fire hazard testing – Part 2-10: Glowing/hot-wire based test methods –

Glow-wire apparatus and common test procedure

IEC 60695-2-13, Fire hazard testing – Part 2-13: Glowing/hot-wire based test methods –

Glow-wire ignition temperature (GWIT) test method for materials

IEC 60695-4:2021, Fire hazard testing – Part 4: Terminology concerning fire tests for

electrotechnical products
ISO 291:2008, Plastics – Standard atmospheres for conditioning and testing

ISO 293, Plastics – Compression moulding of test specimens of thermoplastic materials

ISO 294 (all parts), Plastics – Injection moulding of test specimens of thermoplastic materials

---------------------- Page: 8 ----------------------
IEC 60695-2-12:2021 © IEC 2021 – 7 –

ISO 295, Plastics – Compression moulding of test specimens of thermosetting materials

ISO 13943:2017, Fire safety – Vocabulary
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 13943:2017 and

IEC 60695-4:2012, some of which are reproduced below for the user's convenience, and in

IEC 60695-2-10 regarding times and durations, and the following 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
combustion
exothermic reaction of a substance with an oxidizing agent

Note 1 to entry: Combustion generally emits fire effluent accompanied by flames and/or glowing.

[SOURCE: ISO 13943:2017, 3.55]
3.2
flame, noun

rapid, self-sustaining, sub-sonic propagation of combustion in a gaseous medium, usually with

emission of light
[SOURCE: ISO 13943:2017, 3.159]
3.3
flame event
sustained flaming and/or glowing combustion
3.4
flammability
ability of a material or product to burn with a flame under specified conditions
[SOURCE: ISO 13943:2017, 3.178]
3.5
glowing, noun
luminosity caused by heat
[SOURCE: ISO 13943:2017, 3.196]
3.6
glowing combustion

combustion of a material in the solid phase without flame but with emission of light from the

combustion zone
[SOURCE: ISO 13943:2017, 3.197]
---------------------- Page: 9 ----------------------
– 8 – IEC 60695-2-12:2021 © IEC 2021
3.7
ignition
DEPRECATED: sustained ignition
initiation of combustion
[SOURCE: ISO 13943:2017, 3.217]
3.8
ignition
DEPRECATED: sustained ignition
initiation of sustained flame
[SOURCE: ISO 13943:2017, 3.218]
3.9
molten drip
falling droplet of material which has been softened or liquefied by heat
Note 1 to entry: The droplets can be flaming or not flaming.
[SOURCE: ISO 13943:2017, 3.275]
3.10
preselection

process of assessing and choosing candidate materials, components or subassemblies for

making an end product
[SOURCE: IEC 60695-4:2012, 3.2.21]
4 Test specimens
4.1 Test specimen preparation

Test specimens shall be fabricated using the appropriate ISO method, e.g. casting and

injection moulding in accordance with the ISO 294 series, compression moulding in

accordance with ISO 293 or ISO 295, or transfer moulding to the necessary shape as

specified in 4.2. Where this is not possible, the test specimen shall be cut and/or sliced from a

representative sample of the material (for example, produced using the same fabrication

process as would be used to mould a part of a product).

After any fabrication or cutting operation, all dust and any particles shall be removed from the

surface; cut edges shall be fine sanded to a smooth finish.
4.2 Test specimen dimensions

The dimensions of the planar sections of the test specimens shall be at least 60 mm in length

and 60 mm in width (measured inside the clamping areas) and shall be provided in all

thicknesses under consideration. The preferred values of thickness include
0,1 mm ± 0,02 mm, 0,2 mm ± 0,03 mm, 0,4 mm ± 0,04 mm, 0,75 mm ± 0,15 mm,
1,5 mm ± 0,15 mm, 3,0 mm ± 0,25 mm, or 6,0 mm ± 0,4 mm.

NOTE A set of 30 test specimens per thickness will, in general, be adequate to concurrently establish the GWFI

and the glow wire ignition temperature, GWIT (see IEC 60695-2-13).
---------------------- Page: 10 ----------------------
IEC 60695-2-12:2021 © IEC 2021 – 9 –
4.3 Testing ranges in formulations
4.3.1 General

The results of tests carried out on test specimen sets of different colour, thickness, density,

molecular mass, anisotropic type/direction, additives, fillers, and/or reinforcements can vary.

When agreed between the parties involved, the test programmes outlined in 4.3.2 and 4.3.3

may be employed in order to evaluate these variations.
4.3.2 Density, melt flows and filler/reinforcement

Test specimens covering all combinations of minimum and maximum levels of density, melt

flows and filler/reinforcement content shall be provided and considered representative of the

range if the test results yield the same GWFI. If the test results do not yield the same GWFI

for all test specimens representing the range, evaluation shall be limited to the materials with

the specific levels of density, melt flows and filler/reinforcement tested. In addition, test

specimens with intermediate density, melt flows, and filler/reinforcement content shall be

tested to determine the representative range for each GWFI determination. However, as an

alternative, the least favourable performance of the specific levels of density, melt flows and

filler/reinforcement tested shall be considered representative of intermediate levels without

additional testing.
4.3.3 Colour
When evaluating a range of colours, test specimens that
a) contain no colouring,

b) contain the highest level of organic pigments/colorants/dyes and/or carbon black,

c) contain the highest level of inorganic pigments, and

d) contain pigments/colorants/dyes which are known to adversely affect flammability

characteristics

are considered representative of the colour range if the test results yield the same GWFI.

If the colours do not yield the same GWFI, when evaluating a range of colours, the GWFI with

the least favourable performance should yield the GWFI for an all colour range.
5 Apparatus
The test apparatus of IEC 60695-2-10 shall be used.
6 Temperature measuring system verification

The verification of the temperature measuring system as specified in IEC 60695-2-10 shall

have been performed.
7 Conditioning and test conditions
7.1 Conditioning of test specimens

The test specimens shall be conditioned for a minimum of 48 h at 23 °C ± 2 °C and at a

relative humidity between 40 % and 60 % (in accordance with ISO 291:2008, Clause 6,

Table 2, Class 2). Once removed from the conditioning atmosphere, the test specimens shall

be tested within 4 h.
---------------------- Page: 11 ----------------------
– 10 – IEC 60695-2-12:2021 © IEC 2021
7.2 Conditioning of the wrapping tissue and the wooden board

The wrapping tissue and the wooden board to be placed underneath the test specimen as well

as their conditioning are specified in IEC 60695-2-10. Once removed from the conditioning

atmosphere, the wrapping tissue and wooden board shall be used within 4 h.
7.3 Testing conditions

The test specimens shall be tested in a laboratory atmosphere having a temperature between

15 °C and 35 °C and a relative humidity less than or equal to 75 %.
8 Test procedure
8.1 General
The test specimens shall be identified.
The general test procedure shall be as specified in IEC 60695-2-10.
8.2 Initial test temperatures

The glow-wire is heated to one of the initial test temperatures specified in Table 1, which is

considered to be just high enough to cause ignition. If unknown, the initial test temperature

shall not exceed 650 °C.

NOTE When determining both the GWIT and GWFI, it has been found to be useful to first perform the procedure

in IEC 60695-2-13. Once the GWIT has been determined, this information is useful to set the initial test

temperature for the GWFI test.
Table 1 – Initial test temperatures
Initial test Tolerances
temperatures
°C °C
550 ±10
600 ±10
650 ±10
700 ±10
750 ±10
800 ±15
850 ±15
900 ±15
960 ±15
8.3 Test temperatures

A set of three test specimens shall be prepared for testing at a chosen initial test temperature.

If one of the three test specimens fails to withstand the test criteria as defined in 10.1, the test

shall be repeated with three new test specimens at a test temperature preferably 50 °C (60 °C

for 960 °C) lower.
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IEC 60695-2-12:2021 © IEC 2021 – 11 –

If the three test specimens withstand the test criteria as defined in 10.1, the test shall be

repeated with three new test specimens at a test temperature preferably 50 °C (60 °C for

900 °C) higher.

Repeat the tests with three new test specimens each time and reduce the interval of test

temperatures to 25 °C (30 °C for 960 °C) in the final approach to determine the maximum test

temperature at which all three test specimens withst
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