IEC 60695-2-10:2013

IEC 60695-2-10 ®
Edition 2.0 2013-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
BASIC SAFETY PUBLICATION
PUBLICATION FONDAMENTALE DE SÉCURITÉ
Fire hazard testing –
Part 2-10: Glowing/hot-wire based test methods – Glow-wire apparatus and
common test procedure
Essais relatifs aux risques du feu –
Partie 2-10: Essais au fil incandescent/chauffant – Appareillage et méthode
commune d’essai
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IEC 60695-2-10 ®
Edition 2.0 2013-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
BASIC SAFETY PUBLICATION
PUBLICATION FONDAMENTALE DE SÉCURITÉ

Fire hazard testing –
Part 2-10: Glowing/hot-wire based test methods – Glow-wire apparatus and

common test procedure
Essais relatifs aux risques du feu –

Partie 2-10: Essais au fil incandescent/chauffant – Appareillage et méthode

commune d’essai
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX S
ICS 13.220.40; 29.020 ISBN 978-2-83220-716-1

– 2 – 60695-2-10 © IEC:2013
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 Description of the test apparatus . 8
4.1 Glow-wire . 8
4.2 Test circuit and connections . 8
4.3 Temperature measuring system. 9
4.4 Specified layer . 9
4.5 Test chamber . 9
4.6 Timing device . 10
5 Verification of the apparatus . 10
5.1 Verification of the glow-wire tip . 10
5.2 Verification of the temperature measuring system . 10
6 Conditioning . 10
7 Common test procedure . 10
7.1 Test specimen support . 10
7.2 Glow-wire temperature . 11
7.3 Application of the glow-wire . 11
Annex A (informative) Equipment manufacturers and suppliers . 16
Annex B (informative) Guidance on “ignition” and “flaming” observations . 17
Annex C (informative) Guidance on the verification procedure of the glow-wire
temperature measuring system by the heating current . 19
Bibliography . 21

Figure 1 – Glow-wire and position of thermocouple . 12
Figure 2 – Test circuit . 12
Figure 3 – Test apparatus examples . 14
Figure 4 – Test specimen support (example – see Figures 3a and 3b) . 15
Figure B.1 – Example of a brightly shining flame . 17
Figure B.2 – Example of a blue corona at the glow-wire tip . 18
Figure B.3 – Example of a blue corona near the glow-wire tip . 18
Figure C.1 – Correlation curve between the heating current and the glow-wire
temperature (example) . 20

60695-2-10 © IEC:2013 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FIRE HAZARD TESTING –
Part 2-10: Glowing/hot-wire based test methods –
Glow-wire apparatus and common test procedure

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
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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
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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 60695-2-10 has been prepared by IEC technical committee 89:
Fire hazard testing.
This second edition of IEC 60695-2-10 cancels and replaces the first edition of
IEC 60695-2-10 published in 2000. This edition constitutes a technical revision.
It has the status of a basic safety publication in accordance with IEC Guide 104:2010 and
ISO/IEC Guide 51:1999.
This standard is to be used in conjunction with IEC 60695-2-11, IEC 60695-2-12, and
IEC 60695-2-13.
The main changes with respect to the previous edition are listed below. The rationale can be
found in 89/960A/CC, 89/944A/CC, and 89/1030/CC.

– 4 – 60695-2-10 © IEC:2013
– A table of contents has been added.
– The introduction has been updated to align with other TC89 documents.
– The scope has been clarified to align with other documents in the IEC 60695-2 Glow-wire
series.
– Terms and definitions relevant to this document have been added.
– Clause 4 has been deleted and the remaining clauses renumbered.
– The description of the power supply has been updated with additional details (see 4.1).
– The temperature measuring system (see 4.3) and the description of the specified layer has
been updated (see 4.4).
– New guidance has been introduced to assist in the verification of the temperature
measuring system (see 5.2 and Annex C).
– The common test produced has been clarified (see Clause 7).
– The tolerances have been changed for the dimensions of the glow-wire (see Figure 1).
– New guidance on flaming observations has been added (see Annex B).
The text of this standard is based on the following documents:
FDIS Report on voting
89/1154/FDIS 89/1163/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 60695 series, published under the general title Fire hazard testing,
can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
60695-2-10 © IEC:2013 – 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 was developed, together with its companion,
IEC 60695-1-11, 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:
a) to prevent ignition caused by an electrically energized component part, and
b) to confine any resulting fire within the bounds of the enclosure of the electrotechnical
product in the event of ignition.
Secondary aims of these documents include the minimization of any flame spread beyond the
product’s enclosure and the minimization of 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 dealt with in the overall fire risk 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.
This part of IEC 60695 gives recommendations with regard to the glow-wire test apparatus
and describes a common test procedure for tests applicable to end products and materials to
be used with IEC 60695-2-11 which describes a glow-wire flammability test for end products
(GWEPT), IEC 60695-2-12 which describes a glow-wire flammability index test for materials
(GWFI), and IEC 60695-2-13 which describes a glow-wire ignition temperature test method for
materials (GWIT).
– 6 – 60695-2-10 © IEC:2013
FIRE HAZARD TESTING –
Part 2-10: Glowing/hot-wire based test methods –
Glow-wire apparatus and common test procedure

1 Scope
This part of IEC 60695 specifies the glow-wire apparatus and common test procedure to
simulate the effects of thermal stresses which may be produced by heat sources such as
glowing elements or overloaded resistors, for short periods, in order to assess the fire hazard
by a simulation technique.
The test procedure described in this standard is a common test procedure intended for the
small-scale tests in which a standardized electrically heated wire is used as a source of
ignition.
It is a common part of the test procedures applied to end products and to solid electrical
insulating materials or other solid combustible materials.
A detailed description of each particular test procedure is given in the respective standards
IEC 60695-2-11, IEC 60695-2-12 and IEC 60695-2-13.
This basic safety publication is intended for use by technical committees in the preparation of
standards 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, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60584-1, Thermocouples – Part 1: Reference tables
IEC 60584-2, Thermocouples – Part 2: Tolerances
IEC 60695-2-11, Fire hazard testing – Part 2-11: Glowing/hot-wire based test methods –
Glow-wire flammability test method for end-products
IEC 60695-2-12, Fire hazard testing – Part 2-12: Glowing/hot-wire based test methods –
Glow-wire flammability index (GWFI) test method for materials
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

60695-2-10 © IEC:2013 – 7 –
IEC Guide 104:2010, The preparation of safety publications and the use of basic safety
publications and group safety publications
ISO/IEC Guide 51:1999, Safety aspects – Guidelines for their inclusion in standards
ISO 4046-4:2002, Paper, board, pulps and related terms – Vocabulary – Part 4: Paper and
board grades and converted products
ISO 13943:2008, Fire safety – Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 13943:2008, some
of which are reproduced below for the user’s convenience, as well as the following apply.
3.1
combustible, adjective
capable of being ignited and burned
[SOURCE: ISO 13943:2008, definition 4.43]
3.2
draught-free environment
space in which the results of experiments are not significantly affected by the local air speed
Note 1 to entry: A qualitative example is a space in which a wax candle flame remains essentially undisturbed.
-1 -1
Quantitative examples are small-scale fire tests in which a maximum air speed of 0,1 m × s or 0,2 m × s is
sometimes specified.
[SOURCE: ISO 13943:2008, definition 4.70]
3.3
fire hazard
physical object or condition with a potential for an undesirable consequence from fire
[SOURCE: ISO 13943:2008, definition 4.112]
3.4
fire test
test that measures behaviour of a fire or exposes an item to the effects of a fire
Note 1 to entry: The results of a fire test can be used to quantify fire severity or determine the fire resistance or
reaction to fire of the test specimen.
[SOURCE: ISO 13943:2008, definition 4.132]
3.5
flame, noun
rapid, self-sustaining, sub-sonic propagation of combustion in a gaseous medium, usually with
emission of light
[SOURCE: ISO 13943:2008, definition 4.133]
3.6
flammability
ability of a material or product to burn with a flame under specified conditions

– 8 – 60695-2-10 © IEC:2013
[SOURCE: ISO 13943:2008, definition 4.151]
3.7
ignition
DEPRECATED: sustained ignition
〈general〉 initiation of combustion
[SOURCE: ISO 13943:2008, definition 4.187]
3.8
test temperature
temperature to which the tip of the glow-wire is heated and stabilized prior to any contact with
the test specimen
4 Description of the test apparatus
4.1 Glow-wire
The glow-wire is formed from nickel/chromium (> 77 % Ni/20 ± 1 % Cr) wire, having an overall
diameter of 4,00 mm ± 0,07 mm (before bending). The dimensions of the glow wire loop are
as detailed in Figure 1.
A new glow-wire shall be annealed for a total of at least 10 h by being subjected to a current
of at least 120 A before being used for a test run. The total annealing time may be achieved
cumulatively. To avoid damage, the thermocouple shall not be installed during annealing. At
the end of annealing, the depth of the thermocouple pocket hole shall be verified.
NOTE 1 The temperature of a new glow-wire which has not been annealed gradually lowers during the first few
hours when subjected to a flow of current. After a period of time the temperature then reaches equilibrium.
The test apparatus shall be designed so that the glow-wire is kept in a horizontal plane and
applies a force of 0,95 N ± 0,10 N to the test specimen during the application of the glow-wire.
The force shall be maintained at this value when the glow-wire or the test specimen is moved
horizontally one towards the other. The penetration of the tip of the glow-wire into and through
the test specimen shall be limited to 7 mm ± 0,5 mm.
The test apparatus shall be so designed that burning or glowing particles falling from the test
specimen are able to fall without obstruction onto the layer as specified in 4.4.
Two typical examples of the test apparatus are shown in Figures 3a and 3b.
NOTE 2 The apparatus shown in Figure 3b has been found useful when testing heavy and/or awkwardly shaped
test specimens.
4.2 Test circuit and connections
The glow-wire is heated by a simple electric circuit as shown in Figure 2. There shall be no
feedback mechanism or circuit to maintain the temperature. The power supply for the glow-
wire test apparatus shall be a stabilized voltage source (± 2 % rms). The test circuit shall
contain a current measuring device which indicates a true rms value with a maximum error of
1,0 %.
Due to the high currents involved, it is essential that all electrical connections for the glow-
wire are capable of carrying the current without affecting the performance or long-term
stability of the circuit. For the glow-wire to stud connection, a sufficient contact area (typically
at least 60 mm at each end) is necessary for the stable and loss-less current necessary for
the test. The glow-wire to stud connection shall be tightly screwed, soldered, or brazed
between the glow-wire and studs.

60695-2-10 © IEC:2013 – 9 –
NOTE The typical current necessary for heating the tip to a temperature of 960 °C is between 120 A and 150 A.
4.3 Temperature measuring system
The temperature of the tip of the glow-wire shall be measured by a class 1 (see IEC 60584-2)
mineral-insulated metal-sheathed fine-wire thermocouple with an insulated junction. It shall
have an overall nominal diameter of 1,0 mm. The thermocouple wires shall be suitable for
continuous operation at temperatures up to 960 °C (e.g. chromel/alumel (Type K) – see
IEC 60584-1). The welded point shall be located inside the sheath as close to the tip as
practicable. The sheath shall consist of a metal resistant to continuous operation at a
temperature of at least 1 050 °C.
NOTE A sheath made from a nickel-based heat-resistant alloy satisfies the above requirements.
The glow-wire, with the thermocouple inserted, is shown in Figure 1, Detail Z.
The thermocouple is arranged in a pocket hole, drilled in behind the tip of the glow-wire, and
maintained as a close fit as shown in detail Z of Figure 1. The pocket hole shall be the
smallest diameter that can accommodate the inserted thermocouple in order to reduce the
occurrence of contamination during testing. The thermal contact between the tip of the
thermocouple and the end of the drilled hole shall be maintained. Care shall be taken to
ensure that the thermocouple is able to follow the dimensional changes of the tip of the glow-
wire caused by heating.
The instrument for measuring the thermocouple voltages may consist of any commercial
digital thermometer with a built-in reference junction.
Other temperature measuring instrumentation may be used, but, in case of dispute, the
thermocouple method must be used.
4.4 Specified layer
To evaluate the possible spread of fire, for example by burning or glowing particles falling
from the test specimen, a specified layer is placed underneath the test specimen.
Unless otherwise specified, a single layer of wrapping tissue resting on, and in close contact
with the upper surface of a piece of wooden board (flat and smooth and having a minimum
thickness of 10 mm) is positioned at a distance of 200 mm ± 5 mm below the place where the
glow-wire is applied to the test specimen. See Figures 3a and 3b.
Wrapping tissue (as specified in ISO 4046-4:2002 Clause 4.215) is a soft and strong
2 2
lightweight wrapping tissue with a mass per unit area of between 12 g/m and 30 g/m .
4.5 Test chamber
The apparatus shall be operated in a draught-free environment having sufficient volume such
that
– oxygen depletion during the test does not significantly affect the result; and
– the test specimen can be mounted at least 100 mm from any surface.
NOTE 1 A chamber having a volume of at least 0,5 m is considered to have sufficient volume for the test.
Within the test location, the ambient light falling on the test specimen, not counting that from
the glow-wire, shall not exceed 20 lx. This is measured with a lux meter positioned in place of
the test specimen facing towards the rear part of the location.
NOTE 2 Use of a dark background material will usually help in achieving the 20 lx limit.
After each test, the test location shall be vented to replace any depleted oxygen.

– 10 – 60695-2-10 © IEC:2013
4.6 Timing device
The timing device shall have a resolution of 0,2 s or less.
5 Verification of the apparatus
5.1 Verification of the glow-wire tip
Before each series of tests, it is necessary to inspect the glow-wire tip by measuring and
recording dimension "A" as shown in detail Z of Figure 1. The glow-wire shall be replaced
once this measurement is reduced to 97,5 % or less of the measurement taken before its
initial use.
On completion of each test, clean the tip, if necessary, to remove any residue of previously
tested material, for example by means of a wire brush, and then inspect the tip of the glow-
wire for any cracks. If it is not possible to clean the tip without damaging it (for example when
there is molten glass fibre residue), then the glow-wire shall be replaced.
5.2 Verification of the temperature measuring system
The temperature measuring system described in 4.3 shall be verified periodically using the
procedure described below.
A one-point verification of the temperature of the glow-wire can be performed using a foil of
silver with a purity of at least 99,8 %, approximately 2 mm in area and approximately
0,06 mm thick, placed upon the upper surface of the tip of the glow-wire. The glow-wire shall
be initially set at a temperature slightly lower than the melting point of the foil and allowed to
stabilize. The glow-wire temperature is then increased at a slow heating rate so that the
melting point may be accurately observed. When the silver starts to melt the thermometer
shall indicate 960 °C ± 10 °C. The glow-wire, while still hot, shall be cleared of all traces of
silver immediately after this verification process to reduce the probability of alloying. In case
of dispute, this verification method using a silver foil shall be used.
NOTE Annex C provides guidance to complement the one-point verification procedure of the glow-wire
temperature measuring system by defining the relationship between the heating current and the glow-wire
temperature. In order to assist in setting test temperatures, it has been found useful to develop a reference chart
immediately after verification indicating the current for each temperature. This reference chart can be referred to
on each use to verify that the current-temperature relationship remains consistent. A variation to this relationship of
more than 2 % would suggest that something in the apparatus has changed. In this situation, a verification and
recalibration of the test apparatus is indicated.
6 Conditioning
Before testing, the wooden board and wrapping tissue shall be stored for a minimum of 24 h
in an atmosphere having a temperature between 15 °C and 35 °C and a relative humidity
between 45 % and 75 %.
7 Common test procedure
7.1 Test specimen support
The test specimen shall be mounted or clamped so that
a) the heat losses due to the supporting or fixing means are insignificant (see Figure 4);
b) the planar area of the surface is vertical;
c) the tip of the glow-wire is applied to the centre of the planar area of the surface.
Prior to each set of tests, the glow wire application force shall be checked with a suitable
device. In addition, the free movement of the carriage along the full path shall be checked.

60695-2-10 © IEC:2013 – 11 –
7.2 Glow-wire temperature
CAUTION:
Precautions shall be taken to safeguard the health of personnel conducting tests against
– the risks of explosion, burning or fire;
– the risk of burns and electric shock;
– the inhalation of smoke and/or toxic products; and
– the risks of toxic residues.
The glow-wire is heated to the specified temperature which is measured by means of the
calibrated temperature measurement system. Before bringing the tip of the glow-wire into
contact with the test specimen, care shall be taken to ensure that
a) this temperature is constant within 5 K for a period of at least 60 s;
b) there is no contamination in the thermocouple hole drilled in the glow-wire and there is
appropriate thermocouple to glow-wire contact. Appropriate contact shall be accomplished
by gently pushing the thermocouple into the full depth of the drilled hole;
c) heat radiation does not influence the test specimen during this period by providing an
adequate distance between the specimen and glow-wire i.e. 5,0 cm minimum, or by using
an appropriate screen; and
d) no further adjustment to the heating current is to be made until after the test is completed.
7.3 Application of the glow-wire
The tip of the glow-wire is then brought smoothly into contact with the test specimen for a
duration of 30 s ± 1 s. An approximate rate of approach and withdrawal of 10 mm/s to
25 mm/s has been found to be satisfactory. However, the rate of approach shall be reduced to
near zero upon contact to avoid impact forces exceeding 1,05 N. In those cases where the
material melts away from the glow-wire, the glow-wire shall not be kept in contact with the test
specimen. Following the application time, the glow-wire and the test specimen are slowly
separated, avoiding any further heating of the test specimen and any movement of air which
might affect the result of the test. The penetration of the tip of the glow-wire into and through
the test specimen shall be limited to 7 mm ± 0,5 mm.
NOTE During the tests conducted in accordance with IEC 60695-2-11, IEC 60695-2-12 and IEC 60695-2-13,
guidance on the observation of ignition and flaming can be found in Annex B.

– 12 – 60695-2-10 © IEC:2013
Z
12 ± 4
R26 ± 5
0,6 ± 0,2
R20 ± 5
Detail Z
50 ± 10
+ 2
IEC  632/13
Dimensions in millimetres
Glow-wire material: Nickel/Chromium (>77 %Ni/20 ± 1 %Cr)
Diameter: 4,0 mm ± 0,07 mm (before bending)
Dimension A: (after bending) see 5.1
When forming the glow-wire, care shall be taken to avoid fine cracking at the tip.
NOTE Annealing is a suitable process for prevention of fine cracking at the tip.
Key
1 Glow-wire
2 Thermocouple
3 Stud
Figure 1 – Glow-wire and position of thermocouple

Mains
A
Variable Step down separating Glow-wire
transformer
auto-transformer
IEC  633/13
Figure 2 – Test circuit
–1
32 ± 2
A
60695-2-10 © IEC:2013 – 13 –
6 10
IEC  634/13
Key
1 Test specimen support (see Figure 4)  8 Penetration adjustment
2 Carriage  9 Glow-wire
3 Tensioning cord 10 Cut-out in base plate for falling particles
4 Base plate 11 Glow-wire mounting stud
5 Weight 12 Low-friction rollers
6 Adjustable stop 13 Specified layer
7 Scale to measure height of flame
a) Test apparatus– static glow-wire, moving test specimen (example)

– 14 – 60695-2-10 © IEC:2013
11 3
IEC  635/13
Key
1 Test specimen support (see Figure 4)  8 Penetration adjustment
2 Height adjustment screw  9 Glow-wire
3 Tensioning cord 10 Restraining pin
4 Base plate 11 Glow-wire mounting stud
5 Weight 12 Low-friction rollers
6 Adjustable stop 13 Specified layer
7 Scale to measure height of flame
b) Test apparatus – moving glow-wire, static test specimen (example)
Figure 3 – Test apparatus examples

60695-2-10 © IEC:2013 – 15 –
IEC  636/13
NOTE 1 The design proposed above is to ensure that thermal losses are insignificant.
NOTE 2 No tolerances or dimensions are shown because it is an example only.
Figure 4 – Test specimen support (example – see Figures 3a and 3b)

– 16 – 60695-2-10 © IEC:2013
Annex A
(informative)
Equipment manufacturers and suppliers

Equipment manufacturers and suppliers may be found by searching on the internet.

60695-2-10 © IEC:2013 – 17 –
Annex B
(informative)
Guidance on “ignition” and “flaming” observations

B.1 General
During the tests conducted in accordance with IEC 60695-2-11, IEC 60695-2-12 and
IEC 60695-2-13, the following determination shall apply for “ignition” and flaming”
observations;
a) A flame observed directly at the test specimen (see Figure B.1) shall be judged a clear
indication of ignition. Some materials show a pale flame instead of bright shiny flame.
b) Sometimes a circular corona can be observed around the tip of the glow wire (see
Figure B.2). This corona consists of ionized gas, predominantly blue in colour and is
located in the immediate vicinity of the glow wire. This phenomenon shall not be judged to
be ignition of the test specimen, as long as it does not lead to an ignition of the test
specimen according to a).
c) Ionized gases can sometimes be noticed along the glow wire (see Figure B.3). This
phenomenon shall not be judged to be ignition of the test specimen, as long as it does not
lead to an ignition of the test specimen according to a).
B.2 Examples of ignition and non-ignition

IEC  637/13
Figure B.1 – Example of a brightly shining flame
This indicates that ignition has occurred.

– 18 – 60695-2-10 © IEC:2013
IEC  638/13
Figure B.2 – Example of a blue corona at the glow-wire tip
This does not indicate that ignition has occurred.

IEC  639/13
Figure B.3 – Example of a blue corona near the glow-wire tip
This does not indicate that ignition has occurred.

60695-2-10 © IEC:2013 – 19 –
Annex C
(informative)
Guidance on the verification procedure of the glow-wire
temperature measuring system by the heating current

C.1 Objective
The verification of the glow wire temperature measuring system described in this standard
(see 5.2) uses a one-point measurement based on the melting temperature of silver foil.
However, it assumes that this result covers verification at all other relevant test temperatures.
Annex C provides guidance to complement the one-point verification procedure of the glow-
wire temperature measuring system by defining the relationship between the heating current
and the glow-wire temperature. It provides a practical verification procedure across the entire
range of test temperatures intended for use in IEC 60695-2-11, IEC 60695-2-12 and
IEC 60695-2-13.
C.2 Preparation
The following actions should be taken before establishing the relationship between heating
current and glow-wire temperature measurement:
a) anneal the glow-wire (see 4.1),
b) ensure that the power supply for the glow-wire test apparatus has a stabilized voltage
source (see 4.2),
c) confirm that the glow-wire to stud electrical connection is sufficient to ensure no electrical
loss or temperature rise at the connection which may adversely affect the performance or
long-term stability of the circuit (see 4.2),
d) confirm that there is proper contact between the thermocouple and the glow-wire, taking
into account any dimensional change that may occur upon the heating of the glow wire
(see 4.3),
e) inspect the glow-wire for any damage and, if necessary, clean all contamination from the
glow wire tip (including the thermocouple pocket hole) (see 5.1), and
f) confirm the dimensions of the glow-wire (see 5.1).
C.3 Verification procedure
C.3.1 Observation and measurement
Immediately after completion of the one-point temperature measurement verification (see 5.2),
the glow-wire is heated to 960 °C. After the temperature has stabilized (± 5 °C) for at least
60 s, the heating current and the indicated temperature is recorded. This process is repeated
at intervals of 25 K (30 K above 900 °C) down to 500 °C (i.e. 960 °C, 930 °C, 900 °C, 875 °C,
850 °C, 825 °C, …, 550 °C, 525 °C, 500 °C).
NOTE Dimensional changes to the tip of the glow-wire caused by heating may affect the thermocouple to glow-
wire contact. As stated in Clause C.2, item d), it has been found useful to verify this contact by suitable means as
the temperature is adjusted in accordance with 7.2 b).

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C.3.2 Correlation chart
The heating currents and the corresponding temperatures can be plotted as shown in
Figure C.1. The heating current value calculated from the correlation chart can be used for
setting a specified glow-wire temperature for testing under IEC 60695-2-11, IEC 60695-2-12,
and IEC 60695-2-13.
C.3.3 Frequency of revising the correlation chart
The correlation chart can be used as long as the observed heating current is within 2 % of the
correlation chart value for the relevant glow-wire testing temperature. If the heating current
varies from this range, or a glow-wire is replaced, the glow-wire apparatus should first be
checked and conditioned, then a new correlation chart can be drawn as described in C.3.1
and C.3.2.
1 000
The data presented is an
example. Actual values will
vary based on the apparatus.
60 70 80 90 100 110 120 130 140
Heating current  (A)
IEC  640/13
Figure C.1 – Correlation curve between the heating current
and the glow-wire temperature (example)
Glow-wire temprature  (°C)
60695-2-10 © IEC:2013 – 21 –
Bibliography
IEC 60695-1-10, Fire hazard testing – Part 1-10: Guidance for assessing the fire hazard of
electrotechnical products – General guidelines
IEC 60695-1-11, Fire hazard testing – Part 1-11: Guidance for assessing the fire hazard of
electrotechnical products – Fire hazard assessment

_____________
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SOMMAIRE
AVANT-PROPOS . 23
INTRODUCTION . 25
1 Domaine d’application . 26
2 Références normatives . 26
3 Termes et définitions . 27
4 Description de l’appareillage d’essai . 28
4.1 Fil incandescent . 28
4.2 Circuit et connexions d’essai . 29
4.3 Système de mesure de la température . 29
4.4 Sous-couche spécifiée . 29
4.5 Chambre d’essai . 30
4.6 Chronomètre . 30
5 Vérification de l’appareillage . 30
5.1 Vérification de l’extrémité du fil incandescent . 30
5.2 Vérification du système de mesure de la température . 30
6 Conditionnement .
...