IEC 60364-5-53:2019

Low-voltage electrical installations - Part 5-53: Selection and erection of electrical equipment - Devices for protection for safety, isolation, switching, control and monitoring

IEC 60364-5-53:2019 Deals with general requirements for isolation, switching and control and with the requirements for selection and erection of the devices provided to fulfil such functions. This fourth edition cancels and replaces the third edition published in 2001, Amendment 1:2002 and Amendment 2:2015. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
a) revision of all clauses except 531 and 534;
b) introduction of a new Clause 537 Monitoring;
c) Clause 530 contains all normative references and all terms and definitions.

Installations électriques à basse tension - Partie 5-53: Choix et mise en œuvre des matériels électriques – Dispositifs de protection pour assurer la sécurité, le sectionnement, la coupure, la commande et la surveillance

L'IEC 60364-5-53:2019 traite des exigences relatives:
a) au sectionnement, à la coupure, à la commande et à la surveillance, et
b) au choix et à la mise en œuvre des:
1) dispositifs pour le sectionnement, la coupure, la commande et la surveillance, et
2) dispositifs pour assurer la conformité aux mesures de protection en vue de la sécurité.
Cette quatrième édition annule et remplace la troisième édition parue en 2001, l’Amendement 1:2002 et l’Amendement 2:2015. Cette édition constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
a) révision de tous les articles à l’exception des articles 521 et 534;
b) introduction d’un nouvel Article 537, Surveillance;
c) l’Article 530 contient toutes les références normatives et l’ensemble des termes et définitions.

General Information

• Status: Published
• Publication Date: 09-Dec-2020
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 29.130.01 - Switchgear and controlgear in general
• ICS: 91.140.50 - Electricity supply systems
• Technical Committee: TC 64 - Electrical installations and protection against electric shock
• Drafting Committee: MT 39 - TC 64/MT 39
• Current Stage: PPUB - Publication issued
• Start Date: 22-Feb-2019
• Completion Date: 21-Feb-2019

Relations

• Amended By: IEC 60364-5-53:2019/AMD1:2020 - Amendment 1 - Low-Voltage electrical installations - Part 5-53: Selection and erection of electrical equipment - Devices for protection for safety, isolation, switching, control and monitoring
• Effective Date: 05-Sep-2023
• Revises: IEC 60364-5-53:2001/AMD2:2015 - Amendment 2 - Electrical installations of buildings - Part 5-53: Selection and erection of electrical equipment - Isolation, switching and control
• Effective Date: 05-Sep-2023
• Revises: IEC 60364-5-53:2001/AMD1:2002 - Amendment 1 - Electrical installations of buildings - Part 5-53: Selection and erection of electrical equipment - Isolation, switching and control
• Effective Date: 05-Sep-2023
• Revises: IEC 60364-5-53:2001 - Electrical installations of buildings - Part 5-53: Selection and erection of electrical equipment - Isolation, switching and control
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 60364-5-53 ®
Edition 4.0 2019-02
INTERNATIONAL
STANDARD
colour
inside
Low-voltage electrical installations –
Part 5-53: Selection and erection of electrical equipment – Devices for protection
for safety, isolation, switching, control and monitoring
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 60364-5-53 ®
Edition 4.0 2019-02
INTERNATIONAL
STANDARD
colour
inside
Low-voltage electrical installations –

Part 5-53: Selection and erection of electrical equipment – Devices for

protection for safety, isolation, switching, control and monitoring

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.130.01; 91.140.50 ISBN 978-2-8322-6509-3

– 2 – IEC 60364-5-53:2019  IEC 2019
CONTENTS
FOREWORD . 6
530.1 Scope . 8
530.2 Normative references . 8
530.3 Terms and definitions . 11
530.4 General and common requirements. 14
530.5 Erection of equipment . 14
531 Devices for protection against indirect contact by automatic disconnection of
supply. 14
531.1 Overcurrent protective devices . 14
531.1.1 TN systems . 14
531.1.2 TT systems . 14
531.1.3 IT systems . 15
531.2 Residual current protective devices. 15
531.2.1 General conditions of installation . 15
531.2.2 Selection of devices according to their method of application . 15
531.2.3 TN systems . 15
531.2.4 TT systems . 16
531.2.5 IT systems . 16
531.3 Insulation monitoring devices . 16
532 Devices and precautions for protection against thermal effects . 16
532.1 General . 16
532.2 Locations with a particular risk of fire . 16
532.2.1 General . 16
532.2.2 Locations with external influences BD2, BD3 or BD4 . 17
532.2.3 Locations with external influences BE2 . 17
532.3 Selection of arc fault detection devices (AFDD) . 18
533 Devices for protection against overcurrent . 18
533.1 General requirements . 18
533.1.1 General . 18
533.1.2 Compliance with standards . 18
533.1.3 Fuses . 19
533.2 Selection of devices for protection against overload current . 19
533.2.1 General . 19
533.2.2 Presence of harmonic currents . 20
533.2.3 Unequal current sharing between parallel conductors . 20
533.3 Selection of devices for protection against short-circuit current . 20
533.3.1 Thermal stresses . 20
533.3.2 Breaking capacity . 21
533.4 Positioning of overcurrent protection devices . 21
533.4.1 General . 21
533.4.2 Positioning of devices for overload protection . 21
533.4.3 Positioning of devices for short-circuit protection . 22
533.5 Co-ordination of overload and short-circuit protective functions. 23
533.5.1 Protective functions provided by one device . 23
533.5.2 Protective functions provided by separate devices . 23
534 Devices for protection against transient overvoltages . 23

534.1 General . 23
534.2 Void . 24
534.3 Void . 24
534.4 Selection and erection of SPDs . 24
534.4.1 SPD location and SPD test class . 24
534.4.2 Transient overvoltage protection requirements . 25
534.4.3 Connection types . 25
534.4.4 Selection of SPDs . 27
534.4.5 Protection of the SPD against overcurrent . 31
534.4.6 Fault protection . 33
534.4.7 SPDs installation in conjunction with RCDs. 34
534.4.8 Connections of the SPD . 34
534.4.9 Effective protective distance of SPDs . 36
534.4.10 Connecting conductors of SPDs . 37
535 Co-ordination of protective devices . 37
535.1 Selectivity between overcurrent protective devices . 37
535.1.1 General . 37
535.1.2 Partial selectivity . 38
535.1.3 Full selectivity . 38
535.1.4 Total selectivity . 38
535.1.5 Enhanced selectivity . 38
535.2 Co-ordination between residual current protective devices and OCPDs. 39
535.3 Selectivity between residual current protective devices . 39
535.4 Selectivity of RCD and OCPD . 39
535.5 Combined short-circuit protection of OCPDs . 39
536 Isolation and switching . 40
536.2 Isolation . 40
536.2.1 General . 40
536.2.2 Devices for isolation . 41
536.3 Switching-off for mechanical maintenance . 42
536.3.1 General . 42
536.3.2 Devices for switching-off for mechanical maintenance . 42
536.4 Emergency switching . 43
536.4.1 General . 43
536.4.2 Devices for emergency switching-off . 43
536.4.3 Devices for emergency stopping . 44
536.5 Functional switching (control) . 44
536.5.1 General . 44
536.5.2 Devices for functional switching . 44
537 Monitoring . 45
537.1 General . 45
537.1.1 Monitoring devices . 45
537.1.2 Selection of insulation monitoring devices (IMDs) . 45
537.1.3 Selection of residual current monitoring devices (RCMs) . 45
537.2 IT systems for continuity of supply . 45
537.2.1 General . 45
537.2.2 Insulation monitoring devices (IMDs) . 46
537.2.3 Installation of IMDs . 46
537.3 IT public distribution system . 46

– 4 – IEC 60364-5-
...

IEC 60364-5-53 ®
Edition 4.0 2019-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Low-voltage electrical installations –
Part 5-53: Selection and erection of electrical equipment – Devices
for protection for safety, isolation, switching, control and monitoring

Installations électriques à basse tension –
Partie 5-53: Choix et mise en œuvre des matériels électriques – Dispositifs
de protection pour assurer la sécurité, le sectionnement, la coupure,
la commande et la surveillance

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 60364-5-53 ®
Edition 4.0 2019-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Low-voltage electrical installations –

Part 5-53: Selection and erection of electrical equipment – Devices

for protection for safety, isolation, switching, control and monitoring

Installations électriques à basse tension –

Partie 5-53: Choix et mise en œuvre des matériels électriques – Dispositifs

de protection pour assurer la sécurité, le sectionnement, la coupure,

la commande et la surveillance

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.130.01; 91.140.50 ISBN 978-2-8322-7598-6

– 2 – IEC 60364-5-53:2019 © IEC 2019
CONTENTS
FOREWORD . 6
530.1 Scope . 8
530.2 Normative references . 8
530.3 Terms and definitions . 11
530.4 General and common requirements. 14
530.5 Erection of equipment . 14
531 Devices for protection against indirect contact by automatic disconnection of
supply. 14
531.1 Overcurrent protective devices . 14
531.1.1 TN systems . 14
531.1.2 TT systems . 14
531.1.3 IT systems . 15
531.2 Residual current protective devices. 15
531.2.1 General conditions of installation . 15
531.2.2 Selection of devices according to their method of application . 15
531.2.3 TN systems . 15
531.2.4 TT systems . 16
531.2.5 IT systems . 16
531.3 Insulation monitoring devices . 16
532 Devices and precautions for protection against thermal effects . 16
532.1 General . 16
532.2 Locations with a particular risk of fire . 16
532.2.1 General . 16
532.2.2 Locations with external influences BD2, BD3 or BD4 . 17
532.2.3 Locations with external influences BE2 . 17
532.3 Selection of arc fault detection devices (AFDD) . 18
533 Devices for protection against overcurrent . 18
533.1 General requirements . 18
533.1.1 General . 18
533.1.2 Compliance with standards . 18
533.1.3 Fuses . 19
533.2 Selection of devices for protection against overload current . 19
533.2.1 General . 19
533.2.2 Presence of harmonic currents . 20
533.2.3 Unequal current sharing between parallel conductors . 20
533.3 Selection of devices for protection against short-circuit current . 20
533.3.1 Thermal stresses . 20
533.3.2 Breaking capacity . 21
533.4 Positioning of overcurrent protection devices . 21
533.4.1 General . 21
533.4.2 Positioning of devices for overload protection . 21
533.4.3 Positioning of devices for short-circuit protection . 22
533.5 Co-ordination of overload and short-circuit protective functions. 23
533.5.1 Protective functions provided by one device . 23
533.5.2 Protective functions provided by separate devices . 23
534 Devices for protection against transient overvoltages . 23

534.1 General . 23
534.2 Void . 24
534.3 Void . 24
534.4 Selection and erection of SPDs . 24
534.4.1 SPD location and SPD test class . 24
534.4.2 Transient overvoltage protection requirements . 25
534.4.3 Connection types . 25
534.4.4 Selection of SPDs . 27
534.4.5 Protection of the SPD against overcurrent . 31
534.4.6 Fault protection . 33
534.4.7 SPDs installation in conjunction with RCDs. 34
534.4.8 Connections of the SPD . 34
534.4.9 Effective protective distance of SPDs . 36
534.4.10 Connecting conductors of SPDs . 37
535 Co-ordination of protective devices . 37
535.1 Selectivity between overcurrent protective devices . 37
535.1.1 General . 37
535.1.2 Partial selectivity . 38
535.1.3 Full selectivity . 38
535.1.4 Total selectivity . 38
535.1.5 Enhanced selectivity . 38
535.2 Co-ordination between residual current protective devices and OCPDs. 39
535.3 Selectivity between residual current protective devices . 39
535.4 Selectivity of RCD and OCPD .
...

IEC 60364-5-53 ®
Edition 4.1 2020-12
CONSOLIDATED VERSION
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Low-voltage electrical installations –
Part 5-53: Selection and erection of electrical equipment – Devices
for protection for safety, isolation, switching, control and monitoring

Installations électriques à basse tension –
Partie 5-53: Choix et mise en oeuvre des matériels électriques – Dispositifs
de protection pour assurer la sécurité, le sectionnement, la coupure,
la commande et la surveillance

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 between 2002 and 2015. Some
IEC Customer Service Centre - webstore.iec.ch/csc entries have been collected from earlier publications of IEC
If you wish to give us your feedback on this publication or TC 37, 77, 86 and 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 entre 2002 et 2015. Plus certaines
entrées antérieures extraites des publications des CE 37, 77,
Service Clients - webstore.iec.ch/csc 86 et 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 60364-5-53 ®
Edition 4.1 2020-12
CONSOLIDATED VERSION
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Low-voltage electrical installations –

Part 5-53: Selection and erection of electrical equipment – Devices

for protection for safety, isolation, switching, control and monitoring

Installations électriques à basse tension –

Partie 5-53: Choix et mise en oeuvre des matériels électriques – Dispositifs

de protection pour assurer la sécurité, le sectionnement, la coupure,

la commande et la surveillance

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.130.01; 91.140.50 ISBN 978-2-8322-9201-3

IEC 60364-5-53 ®
Edition 4.1 2020-12
CONSOLIDATED VERSION
REDLINE VERSION
VERSION REDLINE
colour
inside
Low-voltage electrical installations –
Part 5-53: Selection and erection of electrical equipment – Devices
for protection for safety, isolation, switching, control and monitoring

Installations électriques à basse tension –
Partie 5-53: Choix et mise en oeuvre des matériels électriques – Dispositifs
de protection pour assurer la sécurité, le sectionnement, la coupure,
la commande et la surveillance

– 2 – IEC 60364-5-53:2019+AMD1:2020 CSV
© IEC 2020
CONTENTS
FOREWORD . 6
530.1 Scope . 8
530.2 Normative references . 8
530.3 Terms and definitions . 11
530.4 General and common requirements. 14
530.5 Erection of equipment . 14
531 Devices for protection against indirect contact by automatic disconnection of
supply.
531.1 Overcurrent protective devices .
531.1.1 TN systems .
531.1.2 TT systems .
531.1.3 IT systems .
531.2 Residual current protective devices.
531.2.1 General conditions of installation .
531.2.2 Selection of devices according to their method of application .
531.2.3 TN systems .
531.2.4 TT systems .
531.2.5 IT systems .
531.3 Insulation monitoring devices .
531 Equipment for protection against electric shock . 16
531.1 General . 16
531.2 Devices for automatic disconnection of supply . 17
531.2.1 General . 17
531.2.2 Overcurrent protective devices . 17
531.2.3 Residual current protective devices . 19
531.3 Equipment for protection by double or reinforced insulation . 22
531.4 Equipment for protection by electrical separation . 24
531.5 Equipment for protection by extra-low-voltage provided by SELV and PELV
systems . 24
531.5.1 Sources for SELV or PELV systems . 24
531.5.2 Selection of plugs and socket-outlets . 24
531.6 Devices for additional protection . 24
531.7 Monitoring devices . 25
532 Devices and precautions for protection against thermal effects . 25
532.1 General . 25
532.2 Locations with a particular risk of fire . 25
532.2.1 General . 25
532.2.2 Locations with external influences BD2, BD3 or BD4 . 25
532.2.3 Locations with external influences BE2 . 26
532.3 Selection of arc fault detection devices (AFDD) . 26
533 Devices for protection against overcurrent . 27
533.1 General requirements . 27
533.1.1 General . 27
533.1.2 Compliance with standards . 27
533.1.3 Fuses . 28
533.2 Selection of devices for protection against overload current . 28

© IEC 2020
533.2.1 General . 28
533.2.2 Presence of harmonic currents . 29
533.2.3 Unequal current sharing between parallel conductors . 29
533.3 Selection of devices for protection against short-circuit current . 29
533.3.1 Thermal stresses . 29
533.3.2 Breaking capacity . 30
533.4 Positioning of overcurrent protection devices . 30
533.4.1 General . 30
533.4.2 Positioning of devices for overload protection . 30
533.4.3 Positioning of devices for short-circuit protection . 31
533.5 Co-ordination of overload and short-circuit protective functions. 32
533.5.1 Protective functions provided by one device . 32
533.5.2 Protective functions provided by separate devices . 32
534 Devices for protection against transient overvoltages . 32
534.1 General . 32
534.2 Void . 33
534.3 Void . 33
534.4 Selection and erection of SPDs .
...