IEC 60947-5-8:2020

Low-voltage switchgear and controlgear - Part 5-8: Control circuit devices and switching elements - Three-position enabling switches

IEC 60947-5-8:2020 specifies requirements for three-position enabling switches. These switches are used as components of enabling devices to provide signals that,
- when activated, allow machine operation to be initiated by a separate start control, and
- when de-activated,
-- initiate a stop function, and
-- prevent initiation of machine operation.
This second edition cancels and replaces the first edition published in 2006. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
- due to the increasing range of useful applications of three-position enabling switches, note of scope, operational characteristics and tests are reviewed;
- figures for example of devices incorporating enabling switch are added in Annex A;
- new Annex B for procedure to determine reliability data for the switch used in functional safety applications is added.

Appareillage à basse tension - Partie 5-8: Appareils et éléments de commutation pour circuit de commande - Interrupteurs de commande de validation à trois positions

L'IEC 60947-5-8:2020 spécifie les exigences pour les interrupteurs de commande de validation à trois positions. Ces interrupteurs sont utilisés comme composants dans les appareils de commande de validation pour fournir des signaux qui:
- lorsqu’ils sont activés, permettent la mise en marche de la machine par une commande séparée de démarrage; et
- lorsqu’ils sont désactivés:
-- initient une fonction d’arrêt; et
-- évitent la mise en marche de la machine.
Cette deuxième édition annule et remplace la première édition parue en 2006. Cette édition constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
- en raison du nombre croissant d’applications utiles possibles avec les interrupteurs de commande de validation à trois positions, le domaine d’application, les caractéristiques de fonctionnement et les essais sont revus;
- des figures représentant des exemples d’appareils incorporant un interrupteur de commande de validation sont ajoutées dans l’Annexe A;
- une nouvelle Annexe B est ajoutée, incluant une procédure visant à déterminer des données de fiabilité pour l’interrupteur utilisé dans des applications de sécurité fonctionnelle.

General Information

• Status: Published
• Publication Date: 11-Aug-2020
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 29.130.20 - Low voltage switchgear and controlgear
• Technical Committee: SC 121A - Low-voltage switchgear and controlgear
• Drafting Committee: WG 3 - TC 121/SC 121A/WG 3
• Current Stage: PPUB - Publication issued
• Start Date: 07-Aug-2020
• Completion Date: 12-Aug-2020

Relations

• Revises: IEC 60947-5-8:2006 - Low-voltage switchgear and controlgear - Part 5-8: Control circuit devices and switching elements - Three-position enabling switches
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 60947-5-8 ®
Edition 2.0 2020-08
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Low-voltage switchgear and controlgear –
Part 5-8: Control circuit devices and switching elements – Three-position
enabling switches
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.

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].
IEC 60947-5-8 ®
Edition 2.0 2020-08
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Low-voltage switchgear and controlgear –

Part 5-8: Control circuit devices and switching elements – Three-position

enabling switches
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.130.20 ISBN 978-2-8322-8773-6

– 2 – IEC 60947-5-8:2020 RLV © IEC 2020
CONTENTS
FOREWORD . 3
1 General .
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 6
4 Classification . 7
5 Characteristics . 7
6 Product information . 8
7 Normal service, mounting and transport conditions . 10
8 Constructional and performance requirements . 10
9 Tests . 16
Annex A (informative) Example of an enabling devices incorporating
a three-position enabling switch . 23
Annex B (normative) Procedure to determine reliability data for three-position enabling
switches used in functional safety applications . 26
Bibliography . 27

Figure 1 – Operation of three-position enabling switches . 13
Figure 2 – Operating force, travel and enabling contact status . 15
Figure A.1 – Grip type enabling device . 23
Figure A.2 – One hand teaching pendant type enabling device . 23
Figure A.3 – Two hand teaching pendant type enabling device . 24
Figure A.4 – Manual pulse generator . 24
Figure A.5 – Grip type enabling device for hand-held machine . 24
Figure A.6 – Foot actuated enabling device . 25
Figure A.7 – Hoist controller . 25
Figure A.8 – Joystick type enabling device . 25

Table 1 – Force values for F . 15
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR –

Part 5-8: Control circuit devices and switching elements –
Three-position enabling switches

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.
This redline version of the official IEC Standard allows the user to identify the changes
made to the previous edition. A vertical bar appears in the margin wherever a change
has been made. Additions are in green text, deletions are in strikethrough red text.

– 4 – IEC 60947-5-8:2020 RLV © IEC 2020
International Standard IEC 60947-5-8 has been prepared by subcommittee 121A: Low-voltage
switchgear and controlgear, of IEC technical committee 121: Switchgear and controlgear and
their assemblies for low voltage.
This second edition cancels and replaces the first edition published in 2006. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) due to the increasing range of useful applications of three-position enabling switches, note
of scope, operational characteristics and tests are reviewed;
b) figures for example of devices incorporating enabling switch are added in Annex A;
c) new Annex B for procedure to determine reliability data for the switch used in functional
safety applications is added.
The text of this document is based on the following documents:
FDIS Report on voting
121A/358/FDIS 121A/369/RVD
Full information on the voting for the approval of this document can be found in the report on
voting indicated in the above table.
This document should be used in conjunction with IEC 60947-1:2020 and
IEC 60947-5-1:2016.
The provisions of the general rules, IEC 60947-1, are applicable to this standard, where
specifically called for. General rules clauses and subclauses thus applicable, as well as tables,
figures and annexes are identified by a reference to IEC 60947-1, for example 1.2.3 or
Annex A of IEC 60947-1:2020.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 60947 series, under the general title Low-voltage switchgear and
controlgear, can be found on the IEC website.
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.
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.
LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR –

Part 5-8: Control circuit devices and switching elements –
Three-position enabling switches

1 General
1 Scope
This part of IEC 60947 series specifies requirements for three-position enabling switches.
These switches are used as components of enabling devices described in 10.9 of
IEC 60204-1 to provide signals that,
a) when activated, allow machine operation to be initiated by a separate start control, and
b) when de-activated,
– initiate a stop function, and
– prevent initiation of machine operation.
NOTE 1 The enabling control function is described in 9.2.6.3 9.2.3.9 of IEC 60204-1:2016 but the application of
three-position enabling switches is not limited to a component of the enabling device described in IEC 60204-1.
NOTE 2 This document does not deal with enabling devices.
These switches are intended to be connected to circuits which rated voltage does not exceed
250 V AC 50 Hz/60 Hz or 300 V DC.
EXAMPLE Devices incorporating three-position enabling switches are:
– push-button enabling devices;
– grip actuated enabling devices;
– foot actuated enabling devices.
See Annex A for more typical examples.
This document does not apply to:
– three-position enabling switches for non-electrical control circuits, for example hydraulic,
pneumatic;
– enabling switches without three-position mechanism;
– emergency stop devices (see IEC 60947-5-5).
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 60068-2-1:19902007, Environmental testing – Part 2-1: Tests – Test A: Cold
Amendment 1 (1993)
...

IEC 60947-5-8 ®
Edition 2.0 2020-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Low-voltage switchgear and controlgear –
Part 5-8: Control circuit devices and switching elements – Three-position
enabling switches
Appareillage à basse tension –
Partie 5-8: Appareils et éléments de commutation pour circuits de commande –
Interrupteurs de commande de validation à trois positions

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 60947-5-8 ®
Edition 2.0 2020-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Low-voltage switchgear and controlgear –

Part 5-8: Control circuit devices and switching elements – Three-position

enabling switches
Appareillage à basse tension –

Partie 5-8: Appareils et éléments de commutation pour circuits de commande –

Interrupteurs de commande de validation à trois positions

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.130.20 ISBN 978-2-8322-8606-7

– 2 – IEC 60947-5-8:2020 © IEC 2020
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 6
4 Classification . 7
5 Characteristics . 7
6 Product information . 8
7 Normal service, mounting and transport conditions . 9
8 Constructional and performance requirements . 10
9 Tests . 14
Annex A (informative) Example of enabling devices incorporating a three-position
enabling switch . 21
Annex B (normative) Procedure to determine reliability data for three-position enabling
switches used in functional safety applications . 24
Bibliography . 25

Figure 1 – Operation of three-position enabling switches . 12
Figure 2 – Operating force, travel and enabling contact status . 13
Figure A.1 – Grip type enabling device . 21
Figure A.2 – One hand teaching pendant type enabling device . 21
Figure A.3 – Two hand teaching pendant type enabling device . 22
Figure A.4 – Manual pulse generator . 22
Figure A.5 – Grip type enabling device for hand-held machine . 22
Figure A.6 – Foot actuated enabling device . 23
Figure A.7 – Hoist controller . 23
Figure A.8 – Joystick type enabling device . 23

Table 1 – Force values for F . 13
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR –

Part 5-8: Control circuit devices and switching elements –
Three-position enabling switches

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 60947-5-8 has been prepared by subcommittee 121A: Low-voltage
switchgear and controlgear, of IEC technical committee 121: Switchgear and controlgear and
their assemblies for low voltage.
This second edition cancels and replaces the first edition published in 2006. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) due to the increasing range of useful applications of three-position enabling switches, note
of scope, operational characteristics and tests are reviewed;
b) figures for example of devices incorporating enabling switch are added in Annex A;
c) new Annex B for procedure to determine reliability data for the switch used in functional
safety applications is added.
– 4 – IEC 60947-5-8:2020 © IEC 2020
The text of this document is based on the following documents:
FDIS Report on voting
121A/358/FDIS 121A/369/RVD
Full information on the voting for the approval of this document can be found in the report on
voting indicated in the above table.
This document should be used in conjunction with IEC 60947-1:2020 and
IEC 60947-5-1:2016.
The provisions of the general rules, IEC 60947-1, are applicable to this standard, where
specifically called for. General rules clauses and subclauses thus applicable, as well as tables,
figures and annexes are identified by a reference to IEC 60947-1, for example 1.2.3 or
Annex A of IEC 60947-1:2020.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 60947 series, under the general title Low-voltage switchgear and
controlgear, can be found on the IEC website.
The committee has decided that the co
...