IEC 60695-2-12:2021
(Main)Fire hazard testing - Part 2-12: Glowing/hot-wire based test methods - Glow-wire flammability index (GWFI) test method for materials
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 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 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.
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Fire hazard testing –
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IEC 60695-2-12 ®
Edition 3.0 2021-10
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
HORIZONTAL PUBLICATION
Fire hazard testing –
Part 2-12: Glowing/hot-wire based test methods – Glow-wire flammability index
(GWFI) test method for materials
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 13.220.40; 29.020 ISBN 978-2-8322-4436-4
– 2 – IEC 60695-2-12:2021 RLV © IEC 2021
CONTENTS
FOREWORD . 3
INTRODUCTION . 2
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 Test specimens . 7
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 . 10
7.1 Conditioning of test specimens . 10
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 . 11
9 Observations and measurements . 11
9.1 General .
9.1 Initial observations . 11
9.2 Test observations . 12
10 Evaluation of test results . 12
10.1 Test criteria . 12
10.2 Glow-wire flammability index . 12
11 Test report . 13
Bibliography . 14
Table 1 – Initial test temperatures . 11
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
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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 IEC 60695-2-12:2010+AMD1:2014 CSV. A vertical bar
appears in the margin wherever a change has been made. Additions are in green text,
deletions are in strikethrough red text.
– 4 – IEC 60695-2-12:2021 RLV © IEC 2021
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.
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.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
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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 should be 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 red-hot 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 should 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 should 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 may 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.
– 6 – IEC 60695-2-12:2021 RLV © 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 may can allow a reduction of end product testing.
This basic safety publication is focusing on safety test method(s) is primarily intended for use
by technical committees in the preparation of standards 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. The requirements, test methods
or test conditions of this basic safety publication will not apply unless specifically referred to
or included in the relevant 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 60695-1-30:2008, Fire hazard testing – Part 1-30: Guidance for assessing the fire hazard
of electrotechnical products – Preselection testing process – General guidelines
IEC 60695-2-10:2000, 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
IEC Guide 104, The preparation of safety publications and the use of basic safety publications
and group safety publications
ISO/IEC Guide 51, Safety aspects – Guidelines for inclusion in standards
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
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/IEC 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 /IEC 13943:2008, definition 4.46 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 /IEC 13943:2008, definition 4.133 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/IEC 13943:2008, definition 4.168 ISO 13943:2017, 3.196]
– 8 – IEC 60695-2-12:2021 RLV © IEC 2021
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/IEC 13943:2008, definition 4.169 ISO 13943:2017, 3.197]
3.7
ignition
DEPRECATED: sustained ignition
initiation of combustion
[SOURCE: ISO/IEC 13943:2008, definition 4.187 ISO 13943:2017, 3.217]
3.8
ignition
DEPRECATED: sustained ignition
initiation of sustained flame
[SOURCE: ISO/IEC 13943:2008, definition 4.188 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/IEC 13943:2008, definition 4.232 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 60695-1-30:2008, definition 3.2 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, care shall be taken to remove 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 include 0,1 mm ± 0,02 mm, 0,2 mm ±
0,02 mm, 0,4 mm ± 0,05 mm, 0,75 mm ± 0,1 mm, 1,5 mm ± 0,15 mm, 3,0 mm ± 0,2 mm, or
6,0 mm ± 0,4 mm. 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).
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 may 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 may 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 description of the test apparatus is specified in Clause 5 of IEC 60695-2-10.
The wrapping tissue and wooden board to be placed underneath the test specimen are
specified in 5.3 of IEC 60695-2-10.
The test apparatus of IEC 60695-2-10 shall be used.
6 Temperature measuring system verification
The method of verification of the temperature measuring system is as specified in IEC 60695-
2-10 shall have been performed.
– 10 – IEC 60695-2-12:2021 RLV © IEC 2021
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 (see ISO 291, Clause 6, Table 2, Class 2).
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 are
specified in 5.3 of IEC 60695-2-10. They shall be conditioned for a minimum of 48 h at 23 °C
± 2 °C and at a relative humidity between 40 % and 60 %. Once removed from the
conditioning atmosphere, the wrapping tissue and wooden board shall be used within 1 h (see
ISO 291, Clause 6, Table 2, Class 2).
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 and examined visually.
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 should be used as information is useful to set the
initial test temperature for the GWFI test.
Table 1 – Initial test temperatures
Initial test Tolerances
temperatures
°C °KC
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 K °C
(60 K °C for 960 °C) lower.
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 K °C (60 K °C for
900 °C) higher.
Repeat the tests with three new test specimens each time and reduce the interval of test
temperatures to 25 K °C (30 K °C for 960 °C) in the final approach to determine the maximum
test temperature at which all three test specimens withstand the test criteria as defined in
10.1.
However, there is no need to go to the higher temperature if it has already been determined
that at least one of the three test specimens will not withstand the test criteria as defined in
10.1.
NOTE 1 The minimum test temperature is 550 °C. The maximum test temperature is 960 °C.
o
NOTE 2 60 K and 30 K are the appropriate temperature intervals for temperatures above 900 C.
o
NOTE 3 It is recommended to start with a test temperature of 650 C.
9 Observations and measurements
9.1 General
The following observations and measurements shall be recorded.
9.1 Initial observations
After identifying and visually inspecting the test specimens, the following shall be recorded:
a) a description of the tested material, including thickness, colour, type and manufacturer;
b) a description of the method for the preparation of the test specimens, if available;
– 12 – IEC 60695-2-12:2021 RLV © IEC 2021
c) the direction of any anisotropy, if known, relative to the dimensions of the test specimen;
and
d) the pre-test conditioning of the test specimens and wrapping tissue.
9.2 Test observations
During the time of application of the glow-wire, t (30 s ± 1 s), and during a further period of
APP
30 s, time of observation, t , the test specimen and the wrapping tissue placed below it
OBS
shall be observed and the following shall be recorded:
a) the time, t , of the longest sustained flaming and/or glowing combustion observed after
R
the removal of the glow-wire tip from the test specimen (to the nearest 0,5 s),
b) the test temperatures from Clause 8,
c) total consumption of the test specimen, if this occurs,
d) ignition of the wrapping tissue, if this occurs, and
e) additional observations that may be agreed to by both parties.
NOTE If the measured value is 30,2 s this should be recorded as 30,0 s. If the measured value is 30,3 s this
should be recorded as 30,5 s.
a) whether there is no ignition; or, if there is ignition, the time of ignition, t for the test
I
specimen;
a) the time of extinguishment, t ;
E
and t , the calculated value for t shall be
b) based on the recording of measured values t
I E R
recorded as well;
c) the test temperatures from Clause 8;
d) whether the test specimen is totally consumed;
e) whether there is any ignition of the wrapping tissue placed underneath the test specimen;
and
f) additional observations that may be agreed to by both parties.
10 Evaluation of test results
10.1 Test criteria
The test specimen is considered to have withstood this test if there is no ignition, or if all of
the following situations apply:
a) the longest sustained flames or glowing of the test specimen after removal of the glow-
wire, t , extinguish within 30 s;
R
b) the specimen is not totally consumed; and
c) there is no ignition of the wrapping tissue.
The test specimen is considered to have achieved the severity level of a specific test
temperature of T °C, if
a) there is no ignition, or
b) all of the following situations apply when ignition has occurred:
1) flames or glowing combustion of the test specimen extinguish within 30 s after removal
of the glow-wire (t ), i.e. t ≤ 30 s;
OBS R
2) the test specimen is not totally consumed; and
3) the wrapping tissue placed underneath the test specimen does not ignite.
10.2 Glow-wire flammability index
The GWFI is the highest temperature at which three test specimens at the relevant thickness
withstand the test as defined in 10.1.
In those cases where the material under test did not ignite during the determination of the
GWIT (see IEC 60695-2-13) at the highest temperature taken from Table 1, the GWFI test
procedure need not be conducted. The GWFI for this material will be 960 °C at the relevant
thickness.
The GWFI shall be reported in the following manner:
for example, for a test specimen of 3,0 mm thickness and a GWFI temperature of 850 °C:
GWFI: 850 / 3,0
In case of different GWFIs per thickness, these GWFIs shall be reported per thickness.
In those cases where the GWFI is to be utilized over a range of thicknesses, it may be
appropriate to consider the GWFI at the minimum and maximum thickness and the other
preferred thicknesses in the range.
The GWFI representative for a range of thicknesses shall be reported in the following manner,
for example, for a range of thicknesses of 0,75 mm up to 3,0 mm and a GWFI temperature of
850 °C:
GWFI: 850 / 0,75 – 3,0
11 Test report
The test report shall include the following information:
a) a reference to IEC 60695-2-12;
b) the test temperatures from 8.3;
c) the observations and measurements from Clause 9; and
d) the GWFI from 10.2.
– 14 – IEC 60695-2-12:2021 RLV © IEC 2021
Bibliography
IEC 60695-11(all parts), Fire hazard testing – Part 11:Test flames
ISO/IEC 13943:2008, Fire safety – Vocabulary
[1] IEC 60695-1-10, Fire hazard testing – Part 1-10: Guidance for assessing the fire
hazard of electrotechnical products – General guidelines
[2] IEC 60695-1-11, Fire hazard testing – Part 1-11: Guidance for assessing the fire
hazard of electrotechnical products – Fire hazard assessment
[3] IEC 60695-2-11, Fire hazard testing – Part 2-11: Glowing/hot-wire based test
methods – Glow-wire flammability test method for end-products
[4] IEC 60695-1-30, Fire hazard testing – Part 1-30: Guidance for assessing the fire
hazard of electrotechnical products – Preselection testing process – General
guidelines
_____________
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
– 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
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
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.
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.
– 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 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
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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
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 13.220.40; 29.020 ISBN 978-2-8322-1011-1
– 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
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
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.
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.
– 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.
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.
– 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
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]
– 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).
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.
– 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.
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 withstand the test criteria as defined in 10.1.
However, there is no need to go to the higher temperature if it has already been determined
that at least one of the three test specimens will not withstand the test criteria as defined in
10.1.
NOTE The minimum test temperature is 550 °C. The maximum test temperature is 960 °C.
9 Observations and measurements
9.1 Initial observations
After identifying and visually inspecting the test specimens, the following shall be recorded:
a) a description of the tested material, including thickness, colour, type and manufacturer;
b) a description of the method for the preparation of the test specimens, if available;
c) the direction of any anisotropy, if known, relative to the dimensions of the test specimen;
and
d) the pre-test conditioning of the test specimens and wrapping tissue.
9.2 Test observations
During the time of application of the glow-wire, t (30 s ± 1 s), and during a further period of
APP
30 s, time of observation, t , the test specimen and the wrapping tissue placed below it
OBS
shall be observed and the following shall be recorded:
a) whether there is no ignition; or, if there is ignition, the time of ignition, t for the test
I
specimen;
b) the time of extinguishment, t ;
E
c) based on the recording of measured values t and t , the calculated value for t shall be
I E R
recorded as well;
d) the test temperatures from Clause 8;
e) whether the test specimen is totally consumed;
f) whether there is any ignition of the wrapping tissue placed underneath the test specimen;
and
g) additional observations that may be agreed to by both parties.
10 Evaluation of test results
10.1 Test criteria
The test specimen is considered to have achieved the severity level of a specific test
temperature of T °C, if
a) there is no ignition, or
b) all of the following situations apply when ignition has occurred:
1) flames or glowing combustion of the test specimen extinguish within 30 s after removal
of the glow-wire (t ), i.e. t ≤ 30 s;
OBS R
2) the test specimen is not totally consumed; and
– 12 – IEC 60695-2-12:2021 © IEC 2021
3) the wrapping tissue placed underneath the test specimen does not ignite.
10.2 Glow-wire flammability index
The GWFI is the highest temperature at which three test specimens at the relevant thickness
withstand the test as defined in 10.1.
In those cases where the material under test did not ignite during the determination of the
GWIT (see IEC 60695-2-13) at the highest temperature taken from Table 1, the GWFI test
procedure need not be conducted. The GWFI for this material will be 960 °C at the relevant
thickness.
The GWFI shall be reported in the following manner:
for example, for a test specimen of 3,0 mm thickness and a GWFI temperature of 850 °C:
GWFI: 850 / 3,0
In case of different GWFIs per thickness, these GWFIs shall be reported per thickness.
In those cases where the GWFI is to be utilized over a range of thicknesses, it may be
appropriate to consider the GWFI at the minimum and maximum thickness and the other
preferred thicknesses in the range.
The GWFI representative for a range of thicknesses shall be reported in the follow
...
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