IEC TR 61916:2017

IEC TR 61916 ®
Edition 4.0 2017-03
TECHNICAL
REPORT
colour
inside
Electrical accessories – Harmonization of general rules
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IEC TR 61916 ®
Edition 4.0 2017-03
TECHNICAL
REPORT
colour
inside
Electrical accessories – Harmonization of general rules

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.120.01 ISBN 978-2-8322-4117-2

– 2 – IEC TR 61916:2017 © IEC 2017
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
4 General requirements . 8
4.1 General . 8
4.2 Standard conditions for operation in service . 8
4.2.1 Ambient temperature . 8
4.2.2 Altitude . 9
4.2.3 Maximum relative humidity at 40 °C . 9
4.2.4 External magnetic field . 9
4.2.5 Accessory orientation . 9
4.3 Ambient air temperature range for testing . 9
5 Resistance to heat . 9
5.1 General . 9
5.2 Requirements . 9
5.3 Tests . 10
6 Screws, current-carrying parts and connections (electrical and mechanical) . 11
6.1 General . 11
6.2 Types of screw . 11
6.2.1 Thread-forming screw . 11
6.2.2 Thread-cutting screw . 11
6.3 Requirements . 12
6.4 Tests . 14
7 Resistance to abnormal heat and to fire . 15
7.1 General . 15
7.2 Requirements . 15
7.3 Glow-wire flammability test for end-products, IEC 60695-2-11 . 16
7.3.1 Purpose and principle . 16
7.3.2 Test method . 17
7.3.3 Relevance of test data . 17
8 Resistance of insulating materials to tracking . 18
8.1 General . 18
8.2 Requirements . 18
8.3 Tracking index test, IEC 60112 . 18
8.3.1 Purpose and principle . 18
8.3.2 Test method . 18
8.3.3 Relevance of test data . 19
9 Resistance to rusting . 19
9.1 General . 19
9.2 Requirements . 19
9.3 Test . 19
10 Legibility, durability and indelibility of marking . 20
10.1 General . 20
10.2 Requirements . 20

10.3 Test . 20
11 Screw-type terminals for connecting conductors . 21
12 Criteria for tests in accessory standards . 21
13 Tolerances . 21
14 Mechanical strength . 22
14.1 Impact. 22
14.2 Free fall . 22
15 Appropriate dimensioning of insulation distances . 22
15.1 General . 22
15.2 General information . 22
15.3 Dimensioning of clearances . 23
15.4 Dimensioning of creepage distances . 23
15.5 Dimensioning of solid insulation . 25
15.6 Dimensioning of functional insulation . 25
15.7 Practical application of the IEC 60664 series with regards to particular
questions . 25
15.8 Other information useful for TC 23 and its subcommittees . 25
16 Resistance to UV . 26
16.1 General . 26
16.2 Basic principles . 27
16.3 Tests . 27
16.3.1 General . 27
16.3.2 UV test . 27
16.3.3 Mechanical test . 28
Annex A (informative) Material selection process . 29
A.1 General . 29
A.2 Requirements for material selection process . 29
A.3 Material selection process. 30
A.3.1 Material selection based on flammability classifications . 30
A.3.2 Arc ignition test . 30
Annex B (informative) Suggested GWEPT temperatures . 32
Bibliography . 33

Figure 1 – Thread-forming screw . 11
Figure 2 – Thread-cutting screw . 12
Figure 3 – Small parts . 17
Figure 4 – Test piston dimensions. 21

Table 1 – Torque per thread diameter . 14
Table A.1 – Minimum glow-wire ignition temperature (GWIT) of insulating materials
required for the flammability classification of the selected material . 30
Table A.2 – Minimum glow-wire ignition temperature (GWIT) of insulating materials
required for the GWFI classification of the selected material . 30
Table A.3 – Minimum number of arcs required for the flammability classification of the
selected material . 30
Table A.4 – Minimum number of arcs required for the GWFI classification of the
selected material . 30

– 4 – IEC TR 61916:2017 © IEC 2017
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRICAL ACCESSORIES –
HARMONIZATION OF GENERAL RULES

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
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2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
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The main task of IEC technical committees is to prepare International Standards. However, a
technical committee may propose the publication of a Technical Report when it has collected
data of a different kind from that which is normally published as an International Standard, for
example "state of the art".
IEC TR 61916, which is a Technical Report, has been prepared by IEC technical committee
23: Electrical accessories.
This fourth edition cancels and replaces the third edition published in 2014 and constitutes a
technical revision. This edition includes the following significant technical changes with
respect to the previous edition:
a) clarification of the introduction and the scope;
b) clarification of subclause 6.3;
c) modification of Clause 7;
d) modification of Clause 10;
e) addition of Annex B for temperature selection for GWEPT.

The text of this Technical Report is based on the following documents:
Enquiry draft Report on voting
23/742/DTR 23/766/RVDTR
Full information on the voting for the approval of this Technical Report can be found in the
report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
In this Technical Report, the following print types are used:
• requirements proper: in roman type;
• test specifications: in italic type;
• Explanatory matter: in smaller roman type.
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.
A bilingual version of this publication may be issued at a later date.

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.
– 6 – IEC TR 61916:2017 © IEC 2017
INTRODUCTION
The purpose of this document is to have harmonized rules on the same subjects in all the
standards published by IEC TC 23 and its subcommittees, in order to give coordinated
indications to subcommittees when developing their standards.
These recommendations are meant as a guide. Consequently, subcommittees, according to
their own particularities, can use whole or part of the document, which is not meant to be
compulsory.
In this document, the word “shall” is used only to illustrate how the relevant requirement
should be implemented in a product standard and does not itself imply a product requirement
within this document.
In publishing these recommendations, IEC TC 23 wishes to spread the information so that
other committees of the IEC can use these recommendations, if necessary.

ELECTRICAL ACCESSORIES –
HARMONIZATION OF GENERAL RULES

1 Scope
This document, which is a Technical Report, provides guidance on requirements and tests for
subjects applicable to electrical accessories that are within the scope of IEC TC 23 and its
subcommittees.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp

3.1
tracking
progressive formation of conductive paths, which are produced on the surface of or within a
solid insulating material, due to the combined effects of electric stress and electrolytic
contamination
[SOURCE: IEC 60050-212:2010, 212-11-56, modified – The note has been deleted.]
3.2
electric erosion
wearing away of insulating material by the action of electric discharges
[SOURCE: IEC 60050-212:2010, 212-11-55]
3.3
comparative tracking index
CTI
numerical value of the maximum voltage in volts at which a material withstands 50 drops
without tracking
Note 1 to entry: The value of each test voltage and the CTI should be divisible by 25.
[SOURCE: IEC 60050-212:2010, 212-11-59, modified – In the definition, the number of drops
is specified and the text "and without a persistent flame occurring under specified test
conditions" has been removed at the end of the definition. Note 1 to entry has been added.]

– 8 – IEC TR 61916:2017 © IEC 2017
3.4
proof tracking index
PTI
numerical value of the proof voltage in volts at which an insulating material withstands 50
drops without tracking
[SOURCE: IEC 60050-212:2010, 212-11-60, modified – In the definition, the number of drops
is specified. As a consequence, the words “can withstand in a specified tracking test without
tracking failure and without a persistent flame occurring” have been deleted.]
3.5
material selection
process of assessing and choosing candidate materials for parts of components or
subassemblies during the design stage of a product
4 General requirements
4.1 General
Before tests, the specimen is stored for at least 24 h in an atmosphere having a temperature
between 15 °C and 35 °C and relative humidity between 45 % and 75 %, except for the test of
Clause 7 where IEC 60112 applies.
Accessories within the scope of TC 23 standards, and those of its subcommittees, shall be
designed and constructed so that, in normal use, their performance is reliable and safe for the
user and the surroundings.
Standard conditions for operation in service for electrical accessories complying with the
existing standards should be suitable for use at ambient temperatures not normally exceeding
40 °C, and whose average over a period of 24 h does not exceed 35 °C, with a lower limit of
the ambient air temperature of −5 °C.
4.2 Standard conditions for operation in service
4.2.1 Ambient temperature
4.2.1.1 General
Unless covered by a temperature classification, accessories within the scope of TC 23
standards, and those of its subcommittees, should be at least capable of operating under the
following standard conditions.
4.2.1.2 Ambient air temperature range in normal use
Electrical accessories complying with the existing standards are suitable for normal use at
ambient temperatures not normally exceeding 40 °C, but their average over a period of 24 h
does not exceed 35 °C, with a lower limit of the ambient air temperature of −5 °C.
NOTE This temperature range corresponds to AA4 of IEC 60364-5-51:2005, Table 51A. Part of the temperature
range of IEC 60721-3-3, class 3K5, with the high air temperature restricted to 40 °C.
Accessories intended to be used in ambient air temperatures outside the above mentioned
conditions permanently or during a long period shall be covered by special requirements or
tests, if necessary, to be decided by each product committee.
4.2.1.3 Ambient air temperature range in cold climate
In areas where electrical accessories are to be used in cold or arctic climate, any tests may
need to be performed in a suitable cold ambient temperature.

Product committees have the responsibility to evaluate if the accessories intended to be used
in ambient air temperatures in cold climate permanently or during a long period shall be
tested in a temperature corresponding to the climate area, for example AA3 or AA2 of
IEC 60364-5-51:2005, Table 51A.
4.2.2 Altitude
Unless otherwise specified, the accessories are intended to be installed at an altitude not
higher than 2 000 m.
4.2.3 Maximum relative humidity at 40 °C
Unless otherwise specified, the maximum relative humidity at the temperature of 40 °C is
50 %.
Higher relative humidity values are admitted at lower temperature (for example 90 % at
20 °C).
4.2.4 External magnetic field
Unless otherwise specified, the external magnetic field is considered not exceeding five times
the Earth’s magnetic field in any direction.
NOTE When an equipment is installed in proximity to a strong magnetic field, supplementary requirements can be
necessary.
4.2.5 Accessory orientation
Unless otherwise specified, the mounting coordinates of the accessories with respect to the
horizontal or vertical are as stated by the manufacturer, with a tolerance of 2° in any direction.
4.3 Ambient air temperature range for testing
Unless otherwise specified, the tests are carried out at an ambient temperature of (20 ± 5) °C.
5 Resistance to heat
5.1 General
This guidance is applicable to the relevant clause(s) of TC 23 standards, and those of its
subcommittees, covering requirements and tests to determine the resistance to heat of
accessories.
These recommendations are in accordance with IEC 60669-1.
The text includes two subclauses.
• Requirements (5.2).
• Tests (5.3).
For editing purposes, the order and the numbers may be altered if necessary.
5.2 Requirements
Accessories including enclosures, if any, shall be sufficiently resistant to heat.
Compliance is checked by the tests of 5.3.

– 10 – IEC TR 61916:2017 © IEC 2017
5.3 Tests
5.3.1 Verification of resistance to heat:
a) for surface mounting boxes, separable covers, separable cover plates and separable
frames, by the test of 5.3.4;
b) for accessories, with the exception of the parts, if any, covered by a), by the tests of 5.3.2,
5.3.3 and, with the exception of the accessories made from natural or synthetic rubber or
a mixture of both, by the test of 5.3.4.
5.3.2 The specimens are kept for 1 h in a heating cabinet at a temperature of
100 °C ± 2 °C.
During the test, they shall not undergo any change impairing their further use, and sealing
compound, if any, shall not flow to such an extent that live parts are exposed.
After the test and after the specimens have been allowed to cool down to approximately room
temperature, there shall be no access to live parts which are normally not accessible when
the specimens are mounted as in normal use, even if probe B of IEC 61032 is applied with a
force not exceeding 5 N.
After the test, markings shall still be legible.
Discoloration, blisters or slight displacement of the sealing compound is disregarded provided
that safety is not impaired within the meaning of the relevant standard.
5.3.3 Parts of insulating material necessary to retain current-carrying parts and parts of the
earthing circuit in position are subjected to a ball-pressure test according to
IEC 60695-10-2:2014, except that the insulating parts necessary to retain the earthing
terminals in a box shall be tested instead to the test as specified in 5.3.4.
A current-carrying part or a part of the earthing circuit retained by a mechanical means is
considered to be retained in position. The use of grease or the like is not considered to be
mechanical means.
In case of doubt, to determine whether an insulating material is necessary to retain current-
carrying parts and parts of the earthing circuit in position, the specimen is examined without
conductors while held in all positions with the insulating material in question removed.
Before the test is started, the ball and the support on which the specimen shall be placed, are
brought to the temperature specified. The part under test shall be placed on a 3 mm thick
steel plate in direct contact with it, so as to be supported to withstand the test force.
When it is not possible to carry out the test on the specimens, the test shall be carried out on
a piece at least 2 mm thick which is cut out of the specimen. If this is not possible, up to and
including four layers, each cut out of the same specimen, may be used, in which case the
total thickness of the layers should be not less than 2,5 mm.
The test load and the supporting means shall be placed within the heating cabinet for a
sufficient time to ensure that they have attained the stabilized testing temperature before the
test commences.
The test is made in a heating cabinet at a temperature of 125 °C ± 2 °C.
+2
After min, the ball is removed from the specimen which is then cooled and treated
according to Clause 7 of IEC 60695-10-2:2014.

The diameter of the impression caused by the ball is measured in accordance with
IEC 60695-10-2:2014 and shall not exceed 2 mm.
5.3.4 Parts of insulating material not necessary to retain current-carrying parts and parts of
the earthing circuit in position, even though they are in contact with them, are subjected to a
ball pressure test in accordance with 5.3.3, but the test is made at a temperature of
70 °C ± 2 °C or 40 °C ± 2 °C plus the highest temperature rise determined for the relevant
part during the test of clause “Temperature rise test”, whichever is the higher.
6 Screws, current-carrying parts and connections (electrical and mechanical)
6.1 General
This guidance is applicable to the relevant clause(s) of TC 23 standards, and those of its
subcommittees, covering the requirements and tests of screws, current-carrying parts and
connections (electrical and mechanical) of accessories.
These recommendations are in accordance with IEC 60669-1.
The text includes three subclauses as follows.
• Definitions (6.2).
• Requirements (6.3).
• Tests (6.4).
For editing purposes, the order and numbers may be altered, if necessary.
6.2 Types of screw
6.2.1 Thread-forming screw
A tapping screw having an uninterrupted thread which by screwing-in forms a thread by
displacing material in the cavity.
An example of a thread-forming screw is shown in Figure 1.

IEC
Figure 1 – Thread-forming screw
6.2.2 Thread-cutting screw
A screw having an interrupted thread which, by screwing-in, makes a thread by removing
material from the cavity.
An example of thread-cutting screw is shown in Figure 2.

– 12 – IEC TR 61916:2017 © IEC 2017

IEC
Figure 2 – Thread-cutting screw
6.3 Requirements
6.3.1 Connections, electrical or mechanical, using screws and nuts, shall withstand the
mechanical stresses occurring in normal use.
Screws and nuts which transmit mechanical contact pressure for electrical continuity and
conductor retention shall be of metal and shall be in engagement with a metal thread.
Screws for connecting external conductors shall be neither thread-cutting screws nor thread-
forming screws.
Screws and nuts which are operated when mounting an accessory during installation, and/or
which are likely to be operated during the life of the accessory, shall be in engagement with a
metal thread or appropriate requirements shall be considered to ensure that they withstand
the mechanical stresses occurring in normal use.
NOTE Screws and nuts which are operated when mounting the accessory include screws for fixing the cover of
cover plates, etc., but not connecting means for screwed conduits and screws for fixing the base of the accessory.
Compliance is checked by inspection and by the test of 6.4.
6.3.2 For screws in engagement with a thread of insulating material and screws of
insulating material, which are used for the installation of the accessory and/or which are likely
to be operated during the life of the accessory, correct introduction of the screw into the screw
hole or nut shall be ensured.
Screws of insulating materials shall not be used in cases when the replacement with metal
screws could impair the insulation of the accessory.
Compliance is checked by inspection and by manual test.
The requirements with regard to correct introduction are met if introduction of the screw in a
slanting manner is prevented, for example by guiding the screw by the part to be fixed, by a
recess in the female thread or by the use of a screw with the leading thread removed.
6.3.3 Screws and rivets intended to be used for electrical connections and screws and
rivets intended to be used for mechanical connection shall be locked against loosening or
turning.
NOTE Spring washers can provide satisfactory locking. For rivets, a non-circular shank or an appropriate notch
can be sufficient. Sealing compound which softens on heating provides satisfactory locking only for screw
connections not subjected to torsion in normal use.
Compliance is checked by inspection and manual test.
6.3.4 Electrical connections shall be so designed that contact pressure is not transmitted
through insulating material other than ceramic, pure mica or other material with characteristics
no less suitable, unless there is sufficient resiliency in the metallic parts to compensate for
any possible shrinkage or yielding of the insulating material.
Compliance is checked by inspection.

NOTE The suitability of the material is considered with regard to the stability of the dimensions.
6.3.5 Current-carrying parts, including those of terminals (also earthing terminals), shall be
of a metal having, under the conditions occurring in the equipment, mechanical strength,
electrical conductivity and resistance to corrosion adequate for their intended use.
Compliance is checked by inspection and, if necessary, by chemical analysis.
Examples of suitable metals, when used within a permissible temperature range and under
normal conditions of chemical pollution, are:
– copper;
– an alloy containing at least 58 % copper for parts that are worked cold or at least 50 %
copper for other parts;
– stainless steel containing at least 13 % chromium and not more than 0,09 % carbon;
– steel provided with an electroplated coating of zinc according to ISO 2081, the coating
having a thickness of at least
• 5 µm (ISO service condition 1) for ordinary equipment,
• 8 µm (ISO service condition 2) for drip-proof and splash-proof equipment,
• 12 µm (ISO service condition 3) for jet-proof and watertight equipment;
– steel provided with an electroplated coating of nickel and chromium according to
ISO 1456, the coating having a thickness of at least
• 10 µm (ISO service condition 1) for ordinary equipment,
• 20 µm (ISO service condition 2) for drip-proof and splash-proof equipment,
• 30 µm (ISO service condition 3) for jet-proof and watertight equipment;
– steel provided with an electroplated coating of tin, according to ISO 2093, the coating
having a thickness equal to at least that specified for
• 12 µm (ISO service condition 1) for ordinary equipment,
• 20 µm (ISO service condition 2) for drip-proof and splash-proof equipment,
• 30 µm(ISO service condition 3) for jet-proof and watertight equipment;
Parts which may be subjected to mechanical wear, shall not be made of steel provided with
an electroplated coating.
– steel provided with an electroplated coating of zinc: only permitted for prime current-
carrying parts if no fixed connection is intended to be made. For connection, an
electroplated coating of zinc is permissible only on parts which do not participate directly
in current transmission, such as screws or washers used for certain types of terminals in
which they transmit only the contact pressure.
This requirement is not intended to apply to contacts, magnetic circuits, heating elements,
bimetallic components, shunts, parts of electronic devices, etc.
NOTE Screws, nuts, washers, clamping plates and similar parts of terminals are not regarded as current-carrying
parts.
Under moist conditions, metals having a great difference of electrochemical potential with
respect to each other shall not be used in contact with each other.
Compliance is checked by inspection.

– 14 – IEC TR 61916:2017 © IEC 2017
6.3.6 Thread-forming screws and thread-cutting screws shall not be used for the
connection of current-carrying parts. Thread-forming screws and thread-cutting screws may
be used to provide earthing continuity, provided that it is not necessary to disturb the
connection in normal use and at least two screws are used for each connection.
Compliance is checked by inspection.
NOTE The use of thread-forming screws without displacement of material which are operated when mounting the
accessory is under consideration.
6.4 Tests
Compliance with the requirements of 6.3.1 is checked by inspection and by the following test.
The screws and nuts are tightened and loosened:
• 10 times for metal screws in engagement with a thread of insulating material and for
screws of insulating material;
• 5 times in all other cases.
Screws or nuts in engagement with a thread of insulating material and screw of insulating
material are completely removed and re-inserted each time.
The test is made by means of a suitable test screwdriver or spanner applying a torque as
shown in Table 1.
The shape of the blade of the test screwdriver shall suit the head of the screw for screws and
nuts which are operated when mounting and connecting up the device by the following test.
The screws and nuts shall be tightened smoothly. In the case of a test on terminals, the
conductor is moved each time the screw or nut is loosened.
Table 1 – Torque per thread diameter
Torque
Nominal diameter of thread
Nm
mm
I II III IV V
Up to and including 2,8 0,2 – 0,4 0,4 –
over  2,8 up to and including  3,0 0,25 – 0,5 0,5 –
over  3,0 up to and including  3,2 0,3 – 0,6 0,6 –
over  3,2 up to and including  3,6 0,4 – 0,8 0,8 –
over  3,6 up to and including  4,1 0,7 1,2 1,2 1,2 1,2
over  4,1 up to and including  4,7 0,8 1,2 1,8 1,8 1,8
over  4,7 up to and including  5,3 0,8 1,4 2,0 2,0 2,0
over  5,3 up to and including  6,0 1,2 1,8 2,5 3,0 3,0
over  6,0 up to and including  8,0 2,5 2,5 3,5 6,0 4,0
over  8,0 up to and including 10,0 – 3,5 4,0 10,0 6,0
over 10,0 up to and including 12,0 – 4,0 – – 8,0
over 12,0 up to and including 15,0 – 5,0 – – 10,0

Column I applies to screws without head if the screw when tightened does not protrude from
the hole, and to other screws which cannot be tightened by means of a screwdriver with a
blade wider than the diameter of the screw.

Column II applies to nuts of mantle terminals which are tightened by means of a screwdriver.
Column III applies to other screws which are tightened by means of a screwdriver.
Column IV applies to screws and nuts other than nuts of mantle terminals which are tightened
by means other than a screwdriver.
Column V applies to nuts of mantle terminals which are tightened by means other than a
screwdriver.
NOTE For mantle screws, the specific nominal diameter is that of the slotted stud.
For screws with a nominal diameter over 5,3 mm and having a head with a slot, the test is
made twice, first applying to the hexagonal head the torque specified in column IV, and then
on another set of specimens applying the torque specified in column III by means of a
screwdriver.
For smaller screws having a hexagonal head with a slot, only the test with the screwdriver is
made.
During the test, the screwed connection shall not work loose and there shall be no damage,
such as breakage of screws or damage to the head slots, threads, washers or stirrups, that
will impair the further use of the accessory.
7 Resistance to abnormal heat and to fire
7.1 General
Clause 7 is applicable to the relevant clause(s) of TC 23 standards, and those of its
subcommittees, covering requirements and tests to determine the resistance to abnormal heat
and to fire of combustible parts of electrotechnical equipment.
Subclauses 7.2 and 7.3 are meant to give to TC 23 and its subcommittees information on how
to use IEC 60695-2-10:2013 and IEC 60695-2-11:2014.
NOTE IEC 60695-2-11:2014, Annex A gives guidance to assist TC 23 and its subcommittees to select the
appropriate glow-wire temperature.
7.2 Requirements
Parts of insulating material of electrotechnical equipment which might be exposed to
excessive thermal stress due to electric effects and the deterioration of which might impair the
safety of the equipment shall not be unduly affected by heat and by fire generated within the
equipment.
For certain accessories (e.g. switches, plugs, or others) the requirements apply to all parts of
the insulating material, whereas for other accessories (e.g. circuit breakers), which have their
insulating material submitted to severe resistance to fire tests, the requirements apply only to
the external parts of the insulating material.
Parts of insulating material or of other solid combustible material which are liable to propagate
flames inside the equipment may be ignited by glowing wires or glowing elements. Under
certain conditions, for example a fault current flowing through a wire, overloading of
components, and bad connections, certain elements may attain a temperature such that they
will ignite parts in their vicinity.
NOTE In some subcommittees, only external parts are taken into account.
Compliance is checked by the glow-wire test according to 7.3.

– 16 – IEC TR 61916:2017 © IEC 2017
7.3 Glow-wire flammability test for end-products, IEC 60695-2-11
7.3.1 Purpose and principle
7.3.1.1 General
The glow-wire is a specified loop of resistance wire, which is electrically heated to a specified
temperature. The test apparatus is described in IEC 60695-2-10.
When selecting test temperatures, product committees should consider Annex B, which gives
suggested glow-wire end-product test (GWEPT) temperatures.
The purpose of IEC 60695-2-11 is to ensure that, under defined conditions, the glow-wire
does not cause ignition of parts, and that a part, if ignited, has a limited duration of burning
without spreading fire by flames or by burning or glowing particles falling from the test
specimen.
The glow-wire end-product test (GWEPT) shall be conducted on a complete end-product
chosen so that the conditions of the test will not be significantly different from those occurring
in normal use.
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