IEC 60471:2020

Clevis and tongue couplings of string insulator units - Dimensions

IEC 60471:2020 applies to string insulator units of the cap and pin type and also of the long rod type as well as the fittings used with such insulators. The object of this document is to define the dimensions of a series of clevis and tongue couplings to permit the assembly of insulators or fittings supplied by different manufacturers.
This third edition cancels and replaces the second edition published in 1977. This edition includes the following significant technical changes with respect to the previous edition:
- there are no new clevis and tongue couplings;
- For the dimensions of the existing designated size of couplings that characterize the same location, the effective number of the size is unified.

Assemblages à chape et tenon des éléments de chaînes d'isolateurs - Dimensions

IEC 60471:2020 s’applique aux éléments de chaînes d’isolateurs de type à capot, à tige et également à long fût ainsi qu’aux accessoires métalliques qui leur sont associés. L’objet du présent document est de définir les dimensions d’une série d’assemblages à chape et tenon afin de permettre l’assemblage d’isolateurs ou d’accessoires métalliques fournis par différents fabricants.
Cette troisième édition annule et remplace la deuxième édition parue en 1977. La présente édition inclut les modifications techniques majeures suivantes par rapport à l’édition précédente:
- Selon les résultats du questionnaire (36/424/Q), il est confirmé qu’il n’existe pas de nouveaux assemblages à chape et tenon;
- Concernant les dimensions de tailles d’assemblage normalisées existantes qui caractérisent le même emplacement, le nombre de la taille en vigueur est unifié.

General Information

• Status: Published
• Publication Date: 08-Jul-2020
• ICS: 29.080.10 - Insulators
• ICS: 29.240.20 - Power transmission and distribution lines
• Technical Committee: TC 36 - Insulators
• Drafting Committee: MT 21 - TC 36/MT 21
• Current Stage: PPUB - Publication issued
• Start Date: 09-Jul-2020
• Completion Date: 10-Jul-2020

Overview

IEC 60471:2020 is an international standard published by the International Electrotechnical Commission (IEC) that specifies the dimensions of clevis and tongue couplings used in string insulator units. This standard applies to two main types of insulators: cap and pin type, and long rod type, along with their associated fittings. The primary objective of IEC 60471:2020 is to ensure compatibility and interchangeability between insulator components and fittings from different manufacturers by standardizing the dimensions of clevis and tongue couplings.

This latest third edition, published in 2020, supersedes the previous edition from 1977. Key updates include unification of effective size designations without introducing new coupling types.

Key Topics

• Scope: IEC 60471 covers the standardized dimensions for the two-part coupling system consisting of a clevis (female part with U-shaped opening) and a tongue (male part fitting into the clevis). These components are joined by a coupling pin.
• Coupling Types:
  • Couplings with limited movement - Used for cap and pin insulators, ensuring limited tongue movement to prevent electrical contact between insulator parts. Designated by the pin diameter followed by "C" (e.g., 16C).
  • Couplings with unlimited movement - Used for long rod insulators, allowing more freedom of movement, designated by the pin diameter followed by "L" (e.g., 19L).
• Dimensions: The standard defines precise nominal, minimum, and maximum measurements for coupling pins, holes, tongue thickness, clevis opening, and other critical parts, ensuring consistent manufacturing and performance.
• Designation: Couplings are designated by the nominal diameter of the coupling pin and the type letter "C" or "L" depending on insulator type, minimizing confusion with ball and socket coupling designations used in other IEC standards (such as IEC 60120).
• Normative References: Includes relevant IEC publications like IEC 60050-471 for terminology and IEC 60120 for ball and socket coupling dimensions, ensuring comprehensive cross-standard consistency.

Applications

IEC 60471:2020 is essential for manufacturers, designers, and engineers involved in the production and assembly of electrical high-voltage string insulator units. The standard facilitates:

• Interoperability: Allows insulators and fittings produced by different manufacturers to be assembled effectively without dimensional conflicts.
• Quality Assurance: Provides dimensional guidelines that ensure reliable mechanical connections and electrical performance of insulator units.
• Optimum Installation and Maintenance: Standard dimensions help reduce issues like coupling pin insertion difficulties, ensuring smooth installation on power transmission lines.
• Safety and Reliability: Properly dimensioned clevis and tongue couplings prevent unwanted electrical contact and mechanical failure, critical for overhead power distribution safety.

Related Standards

• IEC 60305: Details strength classes coordinating with the dimensions for cap and pin insulators specified in IEC 60471 Table 1.
• IEC 60433: Governs strength classes related to long rod insulator dimensions specified in Table 2 of IEC 60471.
• IEC 60120: Specifies dimensions for ball and socket couplings, complementing the coupling requirements for string insulators but differentiating from clevis and tongue couplings.
• IEC 60050-471: Provides electrotechnical vocabulary relevant to insulators and couplings terminology.
• International Electrotechnical Vocabulary (IEV): Online resource for consistent terminology in electrical standards, aiding understanding of IEC 60471 terms.

---

Keywords: IEC 60471, clevis and tongue couplings, string insulator units, insulator dimensions, cap and pin insulators, long rod insulators, coupling pin, electrical insulator fittings, high-voltage insulators, IEC standard, electrical transmission, coupling dimensions, insulator assembly standards, IEC insulators.

Standards Content (Sample)

IEC 60471 ®
Edition 3.0 2020-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Clevis and tongue couplings of string insulator units – Dimensions

Assemblages à chape et tenon des éléments de chaînes d’isolateurs –
Dimensions
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.

Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite
ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie
et les microfilms, sans l'accord écrit de l'IEC ou du Comité national de l'IEC du pays du demandeur. Si vous avez des
questions sur le copyright de l'IEC ou si vous désirez obtenir des droits supplémentaires sur cette publication, utilisez
les coordonnées ci-après ou contactez le Comité national de l'IEC de votre pays de résidence.

IEC Central Office Tel.: [phone]
3, rue de Varembé [e-mail]
CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigendum or an amendment might have been published.

IEC publications search - webstore.iec.ch/advsearchform Electropedia - www.electropedia.org
The advanced search enables to find IEC publications by a The world's leading online dictionary on electrotechnology,
variety of criteria (reference number, text, technical containing more than 22 000 terminological entries in English
committee,…). It also gives information on projects, replaced and French, with equivalent terms in 16 additional languages.
and withdrawn publications. Also known as the International Electrotechnical Vocabulary

(IEV) online.
IEC Just Published - webstore.iec.ch/justpublished
Stay up to date on all new IEC publications. Just Published IEC Glossary - std.iec.ch/glossary
details all new publications released. Available online and 67 000 electrotechnical terminology entries in English and
once a month by email. French extracted from the Terms and Definitions clause of
IEC publications issued since 2002. Some entries have been
IEC Customer Service Centre - webstore.iec.ch/csc collected from earlier publications of IEC TC 37, 77, 86 and
If you wish to give us your feedback on this publication or CISPR.

need further assistance, please contact the Customer Service

Centre: [e-mail].
A propos de l'IEC
La Commission Electrotechnique Internationale (IEC) est la première organisation mondiale qui élabore et publie des
Normes internationales pour tout ce qui a trait à l'électricité, à l'électronique et aux technologies apparentées.

A propos des publications IEC
Le contenu technique des publications IEC est constamment revu. Veuillez vous assurer que vous possédez l’édition la
plus récente, un corrigendum ou amendement peut avoir été publié.

Recherche de publications IEC - Electropedia - www.electropedia.org
webstore.iec.ch/advsearchform Le premier dictionnaire d'électrotechnologie en ligne au
La recherche avancée permet de trouver des publications IEC monde, avec plus de 22 000 articles terminologiques en
en utilisant différents critères (numéro de référence, texte, anglais et en français, ainsi que les termes équivalents dans
comité d’études,…). Elle donne aussi des informations sur les 16 langues additionnelles. Egalement appelé Vocabulaire
projets et les publications remplacées ou retirées. Electrotechnique International (IEV) en ligne.

IEC Just Published - webstore.iec.ch/justpublished Glossaire IEC - std.iec.ch/glossary
Restez informé sur les nouvelles publications IEC. Just 67 000 entrées terminologiques électrotechniques, en anglais
Published détaille les nouvelles publications parues. et en français, extraites des articles Termes et Définitions des
Disponible en ligne et une fois par mois par email. publications IEC parues depuis 2002. Plus certaines entrées
antérieures extraites des publications des CE 37, 77, 86 et
Service Clients - webstore.iec.ch/csc CISPR de l'IEC.

Si vous désirez nous donner des commentaires sur cette
publication ou si vous avez des questions contactez-nous:
[e-mail].
IEC 60471 ®
Edition 3.0 2020-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Clevis and tongue couplings of string insulator units – Dimensions

Assemblages à chape et tenon des éléments de chaînes d’isolateurs –

Dimensions
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.080.10; 29.240.20 ISBN 978-2-8322-8478-0

– 2 – IEC 60471:2020 © IEC 2020
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Couplings . 6
4.1 General . 6
4.2 Couplings with limited movement . 6
4.3 Couplings with unlimited movement . 6
4.4 Designation of couplings . 6
5 Dimensions. 7
Bibliography . 10

Figure 1 – Dimensions of clevis and tongue couplings for cap and pin insulators . 7
Figure 2 – Dimensions of clevis and tongue couplings for long rod insulators . 8

Table 1 – Dimensions of clevis and tongue couplings for cap and pin insulators . 7
Table 2 – Dimensions of clevis and tongue couplings for long rod insulators . 9

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
CLEVIS AND TONGUE COUPLINGS OF
STRING INSULATOR UNITS – DIMENSIONS

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60471 has been prepared by IEC technical committee 36:
Insulators.
This third edition cancels and replaces the second edition published in 1977. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) According to the results of the questionnaire(36/424/Q), it is confirmed that there are no
new clevis and tongue couplings;
b) For the dimensions of the existing designated size of couplings that characterize the same
location, the effective number of the size is unified.

– 4 – IEC 60471:2020 © IEC 2020
The text of this International Standard is based on the following documents:
FDIS Report on voting
36/484/FDIS 36/494/RVD
Full information on the voting for the approval of this International Standard 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.
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.
CLEVIS AND TONGUE COUPLINGS OF
STRING INSULATOR UNITS – DIMENSIONS

1 Scope
This international standard applies to string insulator units of the cap and pin type and also of
the long rod type as well as the fittings used with such insulators.
The object of this document is to define the dimensions of a series of clevis and tongue
couplings to permit the assembly of insulators or fittings supplied by different manufacturers.
NOTE 1 IEC 60305 gives the coordination between the standardized dimensions of Table 1 and the strength
classes of cap and pin insulator. IEC 60433 gives the coordination between the standardized dimensions of Table 2
and the strength classes of long rod insulators.
NOTE 2 If the dimensions given in Table 1 are not sufficient, higher strength classes are given in IEC 60305.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements of this document. For dated references, only the edition
cited applies. For undated references, the latest edition of the referenced document (including
any amendments) applies.
IEC 60050-471:2007, International Electrotechnical Vocabulary (IEV) – Part 471: Insulators
IEC 60120:2020, Ball and socket couplings of string insulator units - Dimensions
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
clevis and tongue coupling
female part of a clevis and tongue coupling with a U-shaped opening into which the tongue
coupling can be fitted
Note 1 to entry: A clevis contains two holes through which the coupling pin may pass to couple the two
components.
3.2
clevis
female part of a clevis and tongue coupling with a U-shaped opening into which the tongue
coupling can be fitted
Note 1 to entry: A clevis contains two holes through which the coupling pin may pass to couple the two
components.
– 6 – IEC 60471:2020 © IEC 2020
3.3
tongue
male part of a clevis and tongue coupling with a tongue-shaped extremity which fits into the
U-shaped opening of the clevis and which contains a hole through which the coupling pin may
be passed
3.4
coupling pin
rigid pin which passes through the holes in the clevis and tongue to couple them together
Note 1 to entry: On one end, the coupling pin has a stud head and on the other a security device (e.g. split pin) is
placed to hold the pin in its place.
4 Couplings
4.1 General
Two coupling systems are recommended:
– Couplings with limited movement;
– Couplings with unlimited movement.
4.2 Couplings with limited movement
Couplings according to Figure 1, and Table 1, for which a limited movement of the tongue in
the clevis needs to be assured.
This type of coupling is used for cap and pin insulators to ensure that no contact is possible
between the insulating parts of two consecutive insulators. A rectangular shape is
recommended for the tongue.
These couplings are designated by the nominal diameter, expressed in millimetres, of the
coupling pin followed by the letter C.
4.3 Couplings with unlimited movement
Couplings according to Figure 2, and Table 2, for which the movement of the tongue in the
clevis is not limited.
This type of coupling is used for long rod insulators.
These couplings are designated by the nominal diameter, expressed in millimetres, of the
coupling pin followed by the letter L.
4.4 Designation of couplings
Clevis and tongue coupling are designated by the nominal diameter, expressed in millimetres,
of the coupling pin which connects the clevis and tongue. A designated coupling is defined by
the dimensions of the clevis, of the tongue and of the coupling pin.
The Figure 1 and Figure 2 giving the diameter of the coupling pin is followed by the letter C in
the case of couplings for cap and pin insulators or by the letter L in case of long rod insulators.
Any confusion shall be avoided between the designation mentioned above referring to clevis
and tongue couplings and the ball and socket couplings which are designated by nominal pin
diameter which, in certain cases, may be followed by the letter A or B (see IEC 60120),
Therefore, the type of coupling shall always be precisely designated.

5 Dimensions
All the dimensions indicated in Table 1 and Table 2 are given in millimetres, and refer to the
finished articles after surface treatment such as, for instance, galvanizing (see also Figure 1
and Figure 2).
NOTE The outside dimensions of the clevis have not been fixed, since they depend on the mechanical
characteristics of the material used. Therefore, the length of the coupling pin is not fixed and, unless otherwise
agreed, the coupling pin shall be delivered together with the clevis. A security device shall be placed to hold the
pin in its place.
In the case of cap and pin insulators (see IEC 60305), the spacing of the insulators has been chosen so that there
will be no difficulty in inserting the coupling pin in its place. However, for some types of cap and pin insulators with
very deep rims at the lower end of the insulator close to the tongue, it may be difficult to insert the coupling pin. In
such a case, it will be necessary to check that the coupling pin can be inserted.

Figure 1 – Dimensions of clevis and tongue couplings for cap and pin insulators
Table 1 – Dimensions of clevis and tongue couplings for cap and pin insulators
Dimensions in millimetres
Designation 16C 19C 22C
Dimension Min. Nom. Max. Min. Nom. Max. Min. Nom. Max.
Coupling pin diameter d 15,5 16,0 16,3 18,6 19,0 19,4 21,8 22,0 22,6
Hole of clevis and
d 16,7 17,5 18,3 19,8 20,6 21,4 23,0 23,8 24,5
tongue
n
Tongue thickness 12,7 12,7 14,3 19,0 19,0 20,6 22,2 22,2 23,8
Clevis opening B 17,5 18,5 20,0 22,2 23,8 25,4 25,4 27,0 28,6
Tongue m 12,7 13,5 14,3 12,0 12,7 14,3 12,7 14,3 15,9
Clevis F 32,9 — 36,5 36,2 — 39,8 40,9 — 46,0
Clevis H — — 16,5 — — 21,0 — — 23,0
Tongue l 48 — — 56 — — 63 — —
– 8 – IEC 60471:2020 © IEC 2020

Figure 2 – Dimensions of clevis and tongue couplings for long rod insulators

Table 2 – Dimensions of clevis and tongue couplings for long rod insulators
Dimensions
...