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

Status
Published
Publication Date
27-Mar-2017
Technical Committee
Current Stage
PPUB - Publication issued
Start Date
28-Mar-2017
Completion Date
28-Mar-2017
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IEC TR 61916
Edition 4.0 2017-03
TECHNICAL
REPORT
colour
inside
Electrical accessories – Harmonization of general rules
IEC TR 61916:2017-03(en)
---------------------- Page: 1 ----------------------
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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
---------------------- Page: 3 ----------------------
– 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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– 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,

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.

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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

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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.

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.
---------------------- Page: 6 ----------------------
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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– 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.
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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.]

---------------------- Page: 9 ----------------------
– 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.
---------------------- Page: 10 ----------------------
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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– 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 th
...

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