IEC TR 61916:2017
(Main)Electrical accessories - Harmonization of general rules
Electrical accessories - Harmonization of general rules
IEC TR 61916:2017(E) provides guidance on requirements and tests for subjects applicable to electrical accessories that are within the scope of IEC TC 23 and its subcommittees.
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.
General Information
Standards Content (Sample)
IEC TR 61916
®
Edition 4.0 2017-03
TECHNICAL
REPORT
colour
inside
Electrical accessories – Harmonization of general rules
IEC TR 61916:2017-03(en)
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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
Warning! Make sure that you obtained this publication from an authorized distributor.
® Registered trademark of the International Electrotechnical Commission
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– 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
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IEC TR 61916:2017 © IEC 2017 – 3 –
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
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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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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
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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.
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IEC TR 61916:2017 © IEC 2017 – 5 –
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.
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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.
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IEC TR 61916:2017 © IEC 2017 – 7 –
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.]
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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.
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IEC TR 61916:2017 © IEC 2017 – 9 –
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.
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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 th
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