IEC 60364-5-53:2001

IEC 60364-5-53
Edition 3.1 2002-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electrical installations of buildings –
Part 5-53: Selection and erection of electrical equipment – Isolation, switching
and control
Installations électriques des bâtiments –
Partie 5-53: Choix et mise en œuvre des matériels électriques – Sectionnement,
coupure et commande
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IEC 60364-5-53
Edition 3.1 2002-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electrical installations of buildings –
Part 5-53: Selection and erection of electrical equipment – Isolation, switching
and control
Installations électriques des bâtiments –
Partie 5-53: Choix et mise en œuvre des matériels électriques – Sectionnement,
coupure et commande
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CN
CODE PRIX
ICS 29.130; 91.140.50 ISBN 2-8318-6365-1

– 2 – 60364-5-53 © CEI:2001+A1:2002

SOMMAIRE
AVANT-PROPOS.6

530 Introduction .10

530.1 Domaine d’application .10

530.2 Références normatives.10

530.3 (530) Généralités et prescriptions communes .12
531 Dispositifs de protection contre les contacts indirects par coupure automatique
de l'alimentation.12
531.1 Dispositifs de protection à maximum de courant .12
531.2 Dispositifs de protection à courant différentiel-résiduel.14
531.3 Contrôleurs d'isolement.16
532 Dispositifs de protection contre les effets thermiques.16
533 Dispositifs de protection contre les surintensités.16
533.1 Dispositions générales .16
533.2 Choix des dispositifs de protection des canalisations contre les surcharges .18
533.3 Choix des dispositifs de protection des canalisations contre les courts-circuits.18
534 Dispositifs pour la protection contre les surtensions.20
534.1 Généralités.20
534.2 Choix et mise en œuvre des parafoudres dans les installations des bâtiments .20
535 (539) Coordination entre les différents dispositifs de protection .36
535.1 (539.1) Sélectivité entre dispositifs de protection contre les surintensités.36
535.2 (539.2) Association entre les dispositifs de protection à courant
différentiel-résiduel et les dispositifs de protection contre les surintensités.36
535.3 (539.3) Sélectivité entre dispositifs de protection à courant différentiel-résiduel.36
536 (46) Sectionnement et coupure .38
536.0 (460) Introduction.38
536.1 (461) Généralités .38
536.2 (462) Sectionnement.38

536.3 (463) Coupure pour entretien mécanique.42
536.4 (464) Coupure d'urgence y compris l'arrêt d'urgence .44
536.5 (465) Commande fonctionnelle .48
Annexe A (informative) Mise en œuvre de parafoudres en schéma TN.52
Annexe B (informative) Mise en œuvre de parafoudres en schéma TT .54
Annexe C (informative) Mise en œuvre de parafoudres en schéma IT.58
Annexe D (informative) Installation de parafoudres de classes d’essais I, II et III,
par exemple dans les systèmes TN-C-S.60
Annexe E (informative) CEI 60364 – Parties 1 à 6: Restructuration.62
Bibliographie .70

60364-5-53 © IEC:2001+A1:2002 – 3 –

CONTENTS
FOREWORD .7

530 Introduction .11

530.1 Scope.11

530.2 Normative references .11

530.3 (530) General and common requirements.13
531 Devices for protection against indirect contact by automatic disconnection
of supply.13
531.1 Overcurrent protective devices .13
531.2 Residual current protective devices .15
531.3 Insulation monitoring devices .17
532 Devices for protection against thermal effects.17
533 Devices for protection against overcurrent .17
533.1 General requirements.17
533.2 Selection of devices for protection of wiring systems against overloads.19
533.3 Selection of devices for protection of wiring systems against short circuits .19
534 Devices for protection against overvoltages .21
534.1 General .21
534.2 Selection and erection of SPDs in building installations.21
535 (539) Co-ordination of various protective devices.37
535.1 (539.1) Discrimination between overcurrent protective devices.37
535.2 (539.2) Association of residual current protective devices with
overcurrent protective devices.37
535.3 (539.3) Discrimination between residual current protective devices .37
536 (46) Isolation and switching .39
536.0 (460) Introduction.39
536.1 (461) General.39
536.2 (462) Isolation .39

536.3 (463) Switching-off for mechanical maintenance.43
536.4 (464) Emergency switching.45
536.5 (465) Functional switching (control) .49
Annex A (informative) Installation of surge protective devices in TN systems.53
Annex B (informative) Installation of surge protective devices in TT systems .55
Annex C (informative) Installation of surge protective devices in IT systems .59
Annex D (informative) Installation of class I, II and III tested SPDs, for example
in TN-C-S systems.61
Annex E (informative) IEC 60364 – Parts 1 to 6: Restructuring .63
Bibliography .71

– 4 – 60364-5-53 © CEI:2001+A1:2002

Figure 53A – Priorité à la continuité de l’alimentation.28

Figure 53B – Priorité à la continuité de la protection .30

Figure 53C – Association de la continuité de l’alimentation et de la protection .30

Figure 53D – Exemple de mise en œuvre de parafoudres à l’origine de l’installation

ou à sa proximité .34

Figure 53E – Exemple de mise en œuvre de parafoudres à l’origine de l’installation

ou à sa proximité .34

Figure A.1 – Parafoudre en schéma TN .52

Figure B.1 – Parafoudre en aval d’un dispositif différentiel [conformément à 534.2.5 a)] .54

Figure B.2 – Parafoudre en amont d’un dispositif différentiel [conformément à 534.2.5 b)].56
Figure C.1 – Parafoudre en aval d’un dispositif différentiel.58
Figure D.1 – Installation de parafoudres de classes d’essais I, II et III .60
Tableau 53A – Tension de tenue aux chocs en fonction de la tension nominale.40
Tableau 53B – Connexion des parafoudres en fonction des schémas de mise à la terre .22
Tableau 53C – Valeur minimale prescrite de U des parafoudres en fonction des schémas
c
des liaisons à la terre.24
Tableau E.1 – Relations entre les parties restructurées et les parties originales .62
Tableau E.2 – Relations entre les numérotations anciennes et nouvelles.66

60364-5-53 © IEC:2001+A1:2002 – 5 –

Figure 53A – Priority to the continuity of supply .29

Figure 53B – Priority to the continuity of protection .31

Figure 53C – Combination of continuity of supply and continuity of protection.31

Figure 53D – Example of installation of SPDs at or near the origin of the installation .35

Figure 53E – Example of installation of SPDs at or near the origin of the installation .35

Figure A.1 – SPDs in TN systems .53

Figure B.1 – SPDs on the load side of a RCD [according to 534.2.5 a)] .55

Figure B.2 – SPDs on the supply side of RCD [according to 534.2.5 b)].57

Figure C.1 – SPDs on the load side of a RCD .59
Figure D.1 – Installation of class I, II and III tested SPDs.61
Table 53A – Impulse-withstand voltage as a function of the nominal voltage.41
Table 53B – Connection of surge protective devices dependent on system configuration.23
Table 53C – Minimum required U of the SPD dependent on supply system configuration .25
c
Table E.1 – Relationship between restructured and original parts .63
Table E.2 – Relationship between new and old clause numbering.67

– 6 – 60364-5-53 © CEI:2001+A1:2002

COMMISSION ÉLECTROTECHNIQUE INTERNATIONALE

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INSTALLATIONS ÉLECTRIQUES DES BÂTIMENTS –

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

Sectionnement, coupure et commande

AVANT-PROPOS
1) La CEI (Commission Électrotechnique Internationale) est une organisation mondiale de normalisation
composée de l'ensemble des comités électrotechniques nationaux (Comités nationaux de la CEI). La CEI a
pour objet de favoriser la coopération internationale pour toutes les questions de normalisation dans les
domaines de l'électricité et de l'électronique. A cet effet, la CEI, entre autres activités, publie des Normes
internationales. Leur élaboration est confiée à des comités d'études, aux travaux desquels tout Comité national
intéressé par le sujet traité peut participer. Les organisations internationales, gouvernementales et non
gouvernementales, en liaison avec la CEI, participent également aux travaux. La CEI collabore étroitement
avec l'Organisation Internationale de Normalisation (ISO), selon des conditions fixées par accord entre les
deux organisations.
2) Les décisions ou accords officiels de la CEI concernant les questions techniques représentent, dans la mesure
du possible, un accord international sur les sujets étudiés, étant donné que les Comités nationaux intéressés
sont représentés dans chaque comité d’études.
3) Les documents produits se présentent sous la forme de recommandations internationales. Ils sont publiés
comme normes, spécifications techniques, rapports techniques ou guides et agréés comme tels par les
Comités nationaux.
4) Dans le but d'encourager l'unification internationale, les Comités nationaux de la CEI s'engagent à appliquer de
façon transparente, dans toute la mesure possible, les Normes internationales de la CEI dans leurs normes
nationales et régionales. Toute divergence entre la norme de la CEI et la norme nationale ou régionale
correspondante doit être indiquée en termes clairs dans cette dernière.
5) La CEI n’a fixé aucune procédure concernant le marquage comme indication d’approbation et sa responsabilité
n’est pas engagée quand un matériel est déclaré conforme à l’une de ses normes.
6) L’attention est attirée sur le fait que certains des éléments de la présente Norme internationale peuvent faire
l’objet de droits de propriété intellectuelle ou de droits analogues. La CEI ne saurait être tenue pour
responsable de ne pas avoir identifié de tels droits de propriété et de ne pas avoir signalé leur existence.
La Norme internationale CEI 60364-5-53 a été établie par le comité d’études 64 de la CEI:
Installations électriques et protection contre les chocs électriques.
La série des normes CEI 60364 (parties 1 à 6) est actuellement en restructuration, sans
changements techniques, sous une forme simple (voir annexe D).
La présente version consolidée de la CEI 60364-5-53 comprend la troisième édition (2001) et
son amendement 1 (2002) [documents 64/1226/FDIS et 64/1243/RVD].
Le contenu technique de cette version consolidée est donc identique à celui de l'édition de
base et à son amendement; cette version a été préparée par commodité pour l'utilisateur.

Elle porte le numéro d'édition 3.1.
Une ligne verticale dans la marge indique où la publication de base a été modifiée par
l'amendement 1.
Sur décision unanime du Comité d'action (CA/1720/RV (2000-03-21)), les parties de la CEI 60364
établies selon la nouvelle structure n'ont pas été soumises aux Comités nationaux pour
approbation.
Le texte de la présente troisième édition de la CEI 60364-5-53 est le résultat d'une compi-
lation de, et remplace
– la CEI 60364-5-53, deuxième édition (1994) et son corrigendum 1 (1996),
– la CEI 60364-5-534, première édition (1997),
– la CEI 60364-5-537, première édition (1981) et son amendement 1 (1989), et
– la CEI 60364-4-46, première édition (1981).

60364-5-53 © IEC:2001+A1:2002 – 7 –

INTERNATIONAL ELECTROTECHNICAL COMMISSION

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ELECTRICAL INSTALLATIONS OF BUILDINGS –

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

Isolation, switching and control

FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the 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, the IEC publishes International Standards. 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. The 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 the 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 National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form
of standards, technical specifications, technical reports or guides and they are accepted by the National
Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject
of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60364-5-53 has been prepared by IEC technical committee 64:
Electrical installations and protection against electric shock.
The IEC 60364 series (parts 1 to 6), is currently being restructured, without any technical
changes, into a more simple form (see annex D).
This consolidated version of IEC 60364-5-53 consists of the third edition (2001) and its
amendment 1 (2002) [documents 64/1226/FDIS and 64/1243/RVD].
The technical content is therefore identical to the base edition and its amendment and has

been prepared for user convenience.
It bears the edition number 3.1.
A vertical line in the margin shows where the base publication has been modified by
amendment 1.
According to a unanimous decision by the Committee of Action (CA/1720/RV (2000-03-21)),
the restructured parts of IEC 60364 have not been submitted to National Committees for
approval.
The text of this third edition of IEC 60364-5-53 is compiled from and replaces
– IEC 60364-5-53, second edition (1994) and its corrigendum 1 (1996),
– IEC 60364-5-534, first edition (1997),
– IEC 60364-5-537, first edition (1981) and its amendment 1 (1989) and
– IEC 60364-4-46, first edition (1981).

– 8 – 60364-5-53 © CEI:2001+A1:2002

La présente publication a été élaborée, autant que possible, conformément aux Directives
ISO/CEI, partie 3.
Les annexes A, B, C, D et E sont données uniquement à titre d'information.

Le comité a décidé que le contenu de la publication de base et de son amendement ne sera
pas modifié avant 2003. A cette date, la publication sera

• reconduite;
• supprimée;
• remplacée par une édition révisée, ou
• amendée.
60364-5-53 © IEC:2001+A1:2002 – 9 –

This publication has been drafted, as close as possible, in accordance with the ISO/IEC
Directives, Part 3.
Annexes A, B, C, D and E are for information only.

The committee has decided that the contents of the base publication and its amendment will
remain unchanged until 2003. At this date, the publication will be

• reconfirmed;
• withdrawn;
• replaced by a revised edition, or

• amended.
– 10 – 60364-5-53 © CEI:2001+A1:2002

INSTALLATIONS ÉLECTRIQUES DES BÂTIMENTS –

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

Sectionnement, coupure et commande

530  Introduction
530.1 Domaine d’application
La présente partie de la CEI 60364 traite des prescriptions générales relatives au section-
nement, à la coupure et à la commande, ainsi que des prescriptions relatives au choix et à la
mise en œuvre des dispositifs assurant ces fonctions.
530.2 Références normatives
Les documents de référence suivants sont indispensables pour l'application du présent
document. Pour les références datées, seule l'édition citée s'applique. Pour les références
non datées, la dernière édition du document de référence s'applique (y compris les éventuels
amendements).
CEI 60269-3:1987, Fusibles basse tension – Troisième partie: Règles supplémentaires pour
les fusibles destinés à être utilisés par les personnes non qualifiées (fusibles pour usages
essentiellement domestiques et analogues)
CEI 60364-4-41:2001, Installations électriques des bâtiments – Partie 4-41 Protection pour
assurer la sécurité – Protection contre les chocs électriques
CEI 60364-4-42:2001, Installations électriques des bâtiments – Partie 4-42 Protection pour
assurer la sécurité – Protection contre les effets thermiques
CEI 60364-4-43:2001, Installations électriques des bâtiments – Partie 4-43: Protection pour
assurer la sécurité – Protection contre les surintensités
CEI 60364-4-44:2001, Installations électriques des bâtiments – Partie 4-44: Protection pour
assurer la sécurité – Protection contre les perturbations de tension et électromagnétiques
CEI 60364-6-61:2001, Installations électriques des bâtiments – Partie 6-61: Vérification –
Vérification à la mise en service
CEI 60364-7-705:1984, Installation électriques des bâtiments – Septième partie: Règles pour
les installations et emplacements spéciaux – Section 705: Installations électriques dans les

établissements agricoles et horticoles
CEI 60664-1:1992, Coordination de l'isolement des matériels dans les systèmes (réseaux) à
basse tension – Partie 1: Principes, prescriptions et essais
CEI 61008-1:1996, Interrupteurs automatiques à courant différentiel résiduel pour usages domes-
tiques et analogues sans dispositif de protection contre les surintensités incorporé (ID) –
Partie 1: Règles générales
CEI 61009-1:1996: Interrupteurs automatiques à courant différentiel résiduel avec protection
contre les surintensités incorporées pour installations domestiques et analogues (DD) – Partie 1:
Règles générales
CEI 61024-1:1990, Protection des structures contre la foudre – Partie 1: Principes généraux

60364-5-53 © IEC:2001+A1:2002 – 11 –

ELECTRICAL INSTALLATIONS OF BUILDINGS –

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

Isolation, switching and control

530 Introduction
530.1 Scope
This part of IEC 60364 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.
530.2 Normative references
The following referenced documents are indispensable for the application 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 60269-3:1987, Low-voltage fuses – Part 3: Supplementary requirements for fuses for use
by unskilled persons (fuses mainly for household and similar applications)
IEC 60364-4-41:2001, Electrical installations of buildings – IEC 60364-4-41: Protection for
safety – Protection against electric shock
IEC 60364-4-42:2001, Electrical installations of buildings – Part 4-42: Protection for safety –
Protection against thermal effects
IEC 60364-4-43:2001, Electrical installations of buildings – Part 4-43: Protection for safety –
Protection against overcurrent
IEC 60364-4-44:2001, Electrical installations of buildings – Part 4-44: Protection for safety –
Protection against voltage disturbances and electromagnetic disturbances
IEC 60364-6-61:2001, Electrical installations of buildings – Part 6-61: Verification – Initial
verification
IEC 60364-7-705:1984, Electrical installations of buildings – Part 7: Requirements for special
installations or locations – Section 705: Electrical installations of agricultural and horticultural

premises
IEC 60664-1:1992, Insulation coordination for equipment within low-voltage systems – Part 1:
Principles, requirements and tests
IEC 61008-1:1996, Residual current operated circuit-breakers without integral overcurrent
protection for household and similar uses (RCCBs) – Part 1: General rules
IEC 61009-1:1996, Residual current operated circuit-breakers with integral overcurrent
protection for household and similar uses (RCBOs) – Part 1: General rules
IEC 61024-1:1990, Protection of structures against lightning – Part 1: General principles

– 12 – 60364-5-53 © CEI:2001+A1:2002

CEI 61312-1:1995, Protection contre l’impulsion électromagnétique générée par la foudre –
Partie 1: Principes généraux
CEI/TS 61312-2:1999, Protection contre l'impulsion électromagnétique générée par la foudre

(IEMF) – Partie 2: Blindage des structures, équipotentialité dans les structures et mise à la terre

CEI/TS 61312-3:2000, Protection contre l'impulsion électromagnétique générée par la foudre –

Partie 3: Prescriptions relatives aux parafoudres

CEI 61643-1:1998, Dispositifs de protection contre les surtensions connectés aux réseaux de

distribution basse tension – Partie 1: Prescriptions de fonctionnement et méthodes d'essai
Amendement 1 (2001)
CEI 61643-12, Dispositifs de protection contre les surtensions connectés aux réseaux de distri-
1)
bution à basse tension – Partie 12: Prescriptions de fonctionnement et méthodes d’essais
530.3 (530) Généralités et prescriptions communes
La présente partie de la CEI 60364 doit permettre de satisfaire aux mesures de protection
pour assurer la sécurité, aux prescriptions pour assurer un fonctionnement satisfaisant de
l'installation pour l'utilisation prévue, et aux prescriptions appropriées aux conditions
d'influences externes prévisibles. Les matériels doivent être choisis et installés de façon à
satisfaire aux règles énoncées dans la présente partie et, pour autant qu'elles leur soient
applicables, à celles des autres parties de cette norme.
Les prescriptions de la présente partie complètent les règles communes de la CEI 60364-5-51.
530.3.1 (530.1)  Les contacts mobiles de tous les pôles des appareils multipolaires doivent
être couplés mécaniquement de façon qu'ils s'ouvrent ou se ferment pratiquement ensemble;
toutefois, les contacts destinés au neutre peuvent se fermer avant et s'ouvrir après les autres
contacts.
530.3.2 (530.2)  Dans les circuits polyphasés, des dispositifs unipolaires ne doivent pas
être installés dans le conducteur neutre, à l'exception de ceux concernés en 536.2.2.7.
Dans les circuits monophasés, des dispositifs unipolaires ne doivent pas être installés dans le
conducteur neutre, à moins qu'un dispositif à courant différentiel-résiduel satisfaisant aux
règles de l'article 413.1 de la CEI 60364-4-41 ne soit prévu en amont.
530.3.3 (530.3)  Les dispositifs assurant plusieurs fonctions doivent satisfaire à toutes les
prescriptions de la présente partie correspondant à chacune de ces fonctions.
531 Dispositifs de protection contre les contacts indirects par coupure

automatique de l'alimentation
531.1 Dispositifs de protection à maximum de courant
531.1.1 Schéma TN
Dans le schéma TN, les dispositifs de protection contre les surintensités doivent être choisis
et mis en œuvre dans les conditions indiquées en 434.2, à l'article 431 et en 533.3 pour les
dispositifs de protection contre les courts-circuits et doivent satisfaire aux prescriptions
de 413.1.3.3.
531.1.2 Schéma TT
A l'étude.
________
1)
A publier.
60364-5-53 © IEC:2001+A1:2002 – 13 –

IEC 61312-1:1995, Protection against lightning electromagnetic impulse – Part 1: General
principles
IEC/TS 61312-2:1999, Protection against lightning electromagnetic impulse (LEMP) – Part 2:

Shielding of structures, bonding inside structures and earthing

IEC/TS 61312-3:2000, Protection against lightning electromagnetic impulse – Part 3:

Requirements of surge protective devices (SPDs)

IEC 61643-1:1998, Surge-protective device connected to low-voltage power distribution

systems – Part 1: Performance requirements and testing methods

Amendment 1 (2001)
IEC 61643-12, Surge-protective device connected to low-voltage power distribution systems –
1)
Part 12: Performance requirements and testing methods
530.3 (530) General and common requirements
This part of IEC 60364 shall provide compliance with the measures of protection for safety,
the requirements for proper functioning for intended use of the installation, and the
requirements appropriate to the external influences foreseen. Every item of equipment shall
be selected and erected so as to allow compliance with the rules stated in the following
clauses of this part and the relevant rules in other parts of this standard.
The requirements of this part are supplementary to the common rules given in IEC 60364-5-51.
530.3.1 (530.1) The moving contacts of all poles of multipole devices shall be so coupled
mechanically that they make and break substantially together, except that contacts solely
intended for the neutral may close before and open after the other contacts.
530.3.2 (530.2) Except as provided in 536.2.2.7, in multiphase circuits, single-pole devices
shall not be inserted in the neutral conductor.
In single-phase circuits single-pole devices shall not be inserted in the neutral conductor,
unless a residual current device complying with the rules of 413.1 of IEC 60364-4-41 is
provided on the supply side.
530.3.3 (530.3) Devices embodying more than one function shall comply with all the
requirements of this part appropriate to each separate function.

531 Devices for protection against indirect contact by automatic
disconnection of supply
531.1 Overcurrent protective devices
531.1.1 TN systems
In TN systems overcurrent protective devices shall be selected and erected according to the
conditions specified in 434.2 and 431 and in 533.3 for devices for protection against short-
circuit, and shall satisfy the requirements of 413.1.3.3.
531.1.2 TT systems
Under consideration.
________
1)
To be published.
– 14 – 60364-5-53 © CEI:2001+A1:2002

531.1.3 Schéma IT
Lorsque les masses sont interconnectées, les dispositifs de protection contre les surintensités

assurant la protection au deuxième défaut doivent être choisis dans les conditions indiquées

en 531.1.1, compte tenu des prescriptions de 413.1.5.5 de la CEI 60364-4-41.

531.2 Dispositifs de protection à courant différentiel-résiduel

531.2.1 Conditions générales d'installation

Les dispositifs de protection à courant différentiel-résiduel dans des schémas en courant
continu (d.c.) doivent être spécifiquement destinés à la détection de courants différentiels

continus et à la coupure des courants du circuit dans des conditions normales et dans des
situations de défaut.
531.2.1.1 Les dispositifs de protection à courant différentiel-résiduel doivent assurer la
coupure de tous les conducteurs actifs du circuit. Dans le schéma TN-S, le conducteur neutre
peut ne pas être coupé si les conditions d'alimentation sont telles que le conducteur neutre
puisse être considéré comme étant sûrement au potentiel de la terre.
NOTE Les conditions pour vérifier que le conducteur neutre est sûrement au potentiel de la terre sont à l'étude.
531.2.1.2 Aucun conducteur de protection ne doit passer à l'intérieur du circuit magnétique
d'un dispositif de protection à courant différentiel-résiduel.
531.2.1.3 Les dispositifs de protection à courant différentiel-résiduel doivent être choisis et
les circuits électriques divisés, de telle manière que tout courant de fuite à la terre,
susceptible de circuler pendant le fonctionnement normal du ou des appareils alimentés, ne
puisse provoquer la coupure intempestive du dispositif.
NOTE Les dispositifs de protection à courant différentiel-résiduel peuvent fonctionner pour toute valeur de
courant différentiel-résiduel supérieur à 50 % du courant de fonctionnement assigné.
531.2.1.4 Influence des composantes continues
A l'étude.
531.2.1.5 L'utilisation de dispositifs de protection à courant différentiel-résiduel associés à
des circuits ne comportant pas de conducteur de protection ne doit pas être considérée
comme une mesure de protection suffisante contre les contacts indirects, même si leur
courant différentiel-résiduel assigné de fonctionnement est inférieur ou égal à 30 mA.
531.2.2 Choix des dispositifs suivant leur mode de fonctionnement

531.2.2.1 Les dispositifs de protection à courant différentiel-résiduel peuvent comporter ou
non une source auxiliaire, compte tenu des prescriptions de 531.2.2.2.
NOTE La source auxiliaire peut être la source d'alimentation.
531.2.2.2 L'utilisation de dispositifs de protection à courant différentiel-résiduel avec source
auxiliaire ne s'ouvrant pas automatiquement en cas de défaillance de la source auxiliaire est
permise seulement si l'une des deux conditions suivantes est satisfaite:
– la protection contre les contacts indirects conformément à 413.1 de la CEI 60364-4-41 est
assurée même en cas de défaillance de la source auxiliaire;
– les dispositifs sont installés dans des installations exploitées, essayées et vérifiées par
des personnes averties (BA4) ou qualifiées (BA5).

60364-5-53 © IEC:2001+A1:2002 – 15 –

531.1.3 IT systems
Where exposed-conductive-parts are interconnected, overcurrent protective devices for

protection in the event of a second fault shall comply with 531.1.1 taking into account the

requirements of 413.1.5.5 of IEC 60364-4-41.

531.2 Residual current protective devices

531.2.1 General conditions of installation

Residual current protective devices in d.c. systems shall be specially designed for detection
of d.c. residual currents, and to break circuit currents under normal conditions and fault

conditions.
531.2.1.1 A residual current protective device shall ensure the disconnection of all live
conductors in the circuit protected. In TN-S systems, the neutral need not be disconnected if
the supply conditions are such that the neutral conductor can be considered to be reliably at
earth potential.
NOTE The conditions for verification that the neutral conductor is reliably at earth potential are under
consideration.
531.2.1.2 No protective conductor shall pass through the magnetic circuit of a residual
current protective device.
531.2.1.3 Residual current protective devices shall be so selected, and the electrical circuits
so subdivided, that any earth-leakage current which may be expected to occur during normal
operation of the connected load(s) will be unlikely to cause unnecessary tripping of the
device.
NOTE Residual current protective devices may operate at any value of residual current in excess of 50 % of the
rated operating current.
531.2.1.4 Influence of d.c. components
Under consideration.
531.2.1.5 The use of a residual current protective device associated with circuits not having
a protective conductor, even if the rated operating residual current does not exceed 30 mA,
shall not be considered as a measure sufficient for protection against indirect contact.
531.2.2 Selection of devices according to their method of application
531.2.2.1 Residual current protective devices may or may not have an auxiliary source,

taking into account the requirements of 531.2.2.2.
NOTE The auxiliary source may be the supply system.
531.2.2.2 The use of residual current protective devices with an auxiliary source not
operating automatically in the case of failure of the auxiliary source is permitted only if one of
the two following conditions is fulfilled:
– protection against indirect contact according to 413.1 of IEC 60364-4-41 is ensured even
in the case of failure of the auxiliary supply;
– the devices are installed in installations operated, tested and inspected by instructed
persons (BA4) or skilled persons (BA5).

– 16 – 60364-5-53 © CEI:2001+A1:2002

531.2.3 Schéma TN
Si, pour certains appareils ou pour certaines parties d'installation, une ou plusieurs des

conditions énoncées en 413.1.3 ne peuvent pas être respectées, ces parties peuvent être

protégées par un dispositif de protection à courant différentiel-résiduel. Dans ce cas, les

masses peuvent ne pas être raccordées au conducteur de protection du schéma TN lors-

qu'elles sont reliées à une prise de terre dont la résistance est adaptée au courant de

fonctionnement du dispositif de protection à courant différentiel-résiduel. Le circuit protégé

par ce dispositif de protection à courant différentiel-résiduel doit alors être considéré suivant

le schéma TT et les conditions de 413.1.4 s'appliquent.

Si, toutefois, il n'existe pas de prise de terre électriquement distincte, le raccordement des
masses au conducteur de protection doit être effectué en amont du dispositif de protection à
courant différentiel-résiduel.
531.2.4 Schéma TT
Si une installation est protégée par un seul dispositif de protection à courant différentiel-résiduel,
celui-ci doit être placé à l'origine de l'installation, à moins que la partie d'installation comprise
entre l'origine et le dispositif satisfasse à la mesure de protection par emploi de matériel de la
classe II ou par isolation équivalente (voir 413.2).
NOTE Lorsque l'installation comporte plusieurs origines, cette prescription s'applique à chaque origine.
531.2.5  Schéma IT
Lorsque la protection est assurée par un dispositif de protection à courant différentiel-résiduel
et si la coupure au premier défaut n'est pas envisagée, le courant différentiel qui n'assure pas
le fonctionnement du dispositif doit être au moins égal au courant qui circule lors d'un premier
défaut d'isolement à la terre, d'imp
...

IEC 60364-5-53 ®
Edition 3.2 2015-09
CONSOLIDATED VERSION
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Electrical installations of buildings –
Part 5-53: Selection and erection of electrical equipment – Isolation, switching
and control
Installations électriques des bâtiments –
Partie 5-53: Choix et mise en oeuvre des matériels électriques – Sectionnement,
coupure et commande
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IEC 60364-5-53 ®
Edition 3.2 2015-09
CONSOLIDATED VERSION
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Electrical installations of buildings –

Part 5-53: Selection and erection of electrical equipment – Isolation, switching

and control
Installations électriques des bâtiments –

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

coupure et commande
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.130; 91.140.50 ISBN 978-2-8322-2931-6

IEC 60364-5-53 ®
Edition 3.2 2015-09
CONSOLIDATED VERSION
REDLINE VERSION
VERSION REDLINE
colour
inside
Electrical installations of buildings –
Part 5-53: Selection and erection of electrical equipment – Isolation, switching
and control
Installations électriques des bâtiments –
Partie 5-53: Choix et mise en oeuvre des matériels électriques – Sectionnement,
coupure et commande
– 2 – IEC 60364-5-53:2001+AMD1:2002
+AMD2:2015 CSV © IEC 2015
CONTENTS
FOREWORD . 5
530 Introduction . 7
530.1 Scope . 7
530.2 Normative references . 7
530.3 (530) General and common requirements . 8
531 Devices for protection against indirect contact by automatic disconnection of
supply . 9
531.1 Overcurrent protective devices . 9
531.2 Residual current protective devices . 9
531.3 Insulation monitoring devices . 10
532 Devices for protection against thermal effects . 11
533 Devices for protection against overcurrent . 11
533.1 General requirements . 11
533.2 Selection of devices for protection of wiring systems against overloads . 11
533.3 Selection of devices for protection of wiring systems against short circuits . 11
534 Devices for protection against electromagnetic and voltage disturbances
transient overvoltages. 12
534.1 (534) Devices for protection against overvoltage General . 12
534.2 Erection of surge protective devices in building installations Void . 12
534.3 Devices for protection against undervoltage Terms and definitions . 14
534.4 Selection and erection of SPDs . 16
535 (539) Co-ordination of various protective devices . 31
535.1 (539.1) Discrimination between overcurrent protective devices . 31
535.2 (539.2) Association of residual current protective devices with overcurrent
protective devices . 31
535.3 (539.3) Discrimination between residual current protective devices . 32
536 (46) Isolation and switching . 32
536.0 (460) Introduction . 32
536.1 (461) General . 32
536.2 (462) Isolation . 32
536.3 (463) Switching-off for mechanical maintenance . 34
536.4 (464) Emergency switching . 35
536.5 (465) Functional switching (control) . 37
Annex A (informative) Installation of surge protective devices in TN-systems .
Annex A (informative) SPD installation –  Examples of installation diagrams
according to system configurations . 40
A.1 TT system – 3 phase supply plus neutral . 40
A.2 TN-C and TN-C-S systems – 3 phase supply . 44
A.3 TN-S system – 3 phase supply plus neutral . 48
A.4 IT system – 3 phase supply with or without neutral . 50
Annex B (informative) Installationof surge protective devices in TT-systems .
Annex B (informative) Installation supplied by overhead lines . 55
Annex C (informative) Installation of surge protective devices in IT-systems .
Annex C (informative) List of notes concerning certain countries . 57
Annex D (informative) IEC 60364 – Parts 1 to 6: Restructuring . 60

+AMD2:2015 CSV © IEC 2015
Bibliography . 64

Figure 534.1 – Example of installation of class I, class II and class III tested SPDs . 14
Figure 534.2 – Connection type CT1 (4+0-configuration) for a three-phase system with
neutral . 15
Figure 534.3 – Connection type CT1 (3+0-configuration) for a three-phase system . 15
Figure 534.4 – Connection type CT2 (e.g. 3+1-configuration) for a three-phase system
with neutral . 16
Figure 534.5 – Connection points of an SPD assembly . 21
Figure 534.6 – Example of overcurrent protection in the SPD branch by using a
dedicated external overcurrent protective device . 23
Figure 534.7 – Protective device, which is a part of the installation, also used to
protect the SPD . 24
Figure 534.8 – Connection of the SPD . 26
Figure 534.9 – Example of installation of an SPD in order to decrease lead length of
SPD supply conductors . 27
Figure A.1 – SPDs in TN-systems .
Figure A.1 – Example of SPDA installation with connexion type CT2 on the supply
side (upstream) of the main RCD in TT system . 37
Figure A.2 – Example of SPD installation with connexion type CT2 on the supply side
(upstream) of the main RCD in TT system . 38
Figure A.3 – Example of SPDA installation on the load side (downstream) of the main
RCD in TT system . 39
Figure A.4 – Example of SPD installation on the load side (downstream) of the RCD in
TT system . 40
Figure A.5 – Example of SPDA installation in TN-C system . 41
Figure A.6 – Example of SPD installation with connexion type CT1 in TN-C system . 42
Figure A.7 – Example of SPD installation in TN-C-S system where the PEN is
separated into PE and N at the origin of the installation (upstream of the SPD) . 43
Figure A.8 – Example of SPDs installation in TN-C-S in different distribution boards . 44
Figure A.9 – Example of SPDA installation in TN-S system . 45
Figure A.10 – Example of SPDs installation in TN-S . 46
Figure A.11 – Example of SPDA installation in IT system with neutral . 47
Figure A.12 – Example of SPD installation in IT system without neutral . 48
Figure A.13 – Example of SPD installation in IT system with neutral . 49
Figure B.1 – SPDs on the load side of RCD .
Figure B.2 – SPDs on the supply side of RCD .
Figure C.1 – SPDs on the load side of RCD .

Table 534.1 – Required rated impulse voltage of equipment . 18
Table 534.2 – U of the SPD dependent on supply system configuration . 19
c
Table 534.3 – Nominal discharge current (I ) in kA depending on supply system and
n
connection type . 20
Table 534.4 – Selection of impulse discharge current (I ) where the building is
imp
protected against direct lightning strike . 20
Table 534.5 – Connection of the SPD dependent on supply system . 25

– 4 – IEC 60364-5-53:2001+AMD1:2002
+AMD2:2015 CSV © IEC 2015
Table 53A – Impulse-withstand voltage as a function of the nominal voltage . 30
Table B.1 – Selection of impulse discharge current (I ) . 52
imp
Table D.1 – Relationship between restructured and original parts . 57
Table D.2 – Relationship between new and old clause numbering . 59

+AMD2:2015 CSV © IEC 2015
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRICAL INSTALLATIONS OF BUILDINGS –
Part 5-53: Selection and erection of electrical equipment –
Isolation, switching and control
FOREWORD
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This consolidated version of the official IEC Standard and its amendments has been prepared
for user convenience.
IEC 60364-5-53 edition 3.2 contains the third edition (2001-08) [CA/1720/RV], its amendment 1
(2002-04) [documents 64/1226/FDIS and 64/1243/RVD] and its amendment 2 (2015-09)
[documents 64/2031/FDIS and 64/2072/RVD].
In this Redline version, a vertical line in the margin shows where the technical content is
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text. A separate Final version with all changes accepted is available in this publication.

– 6 – IEC 60364-5-53:2001+AMD1:2002
+AMD2:2015 CSV © IEC 2015
International Standard IEC 60364-5-53 has been prepared by IEC technical committee 64:
Electrical installations and protection against electric shock.
The IEC 60364 series (parts 1 to 6), is currently being restructured, without any technical
changes, into a more simple form (see annex D).
The text of this third edition of IEC 60364-5-53 is compiled from and replaces
– IEC 60364-5-53, second edition (1994) and its corrigendum 1 (1996),
– IEC 60364-5-534, first edition (1997),
– IEC 60364-5-537, first edition (1981) and its amendment 1 (1989) and
– IEC 60364-4-46, first edition (1981).
This publication has been drafted with the ISO/IEC Directives, Part 2.
Annexes A, B, C and D are for information only.
The committee has decided that the contents of the base publication and its amendments will
remain unchanged until the stability date indicated on the IEC web site under
"http://webstore.iec.ch" in the data related to the specific publication. At this date, the
publication 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.
+AMD2:2015 CSV © IEC 2015
ELECTRICAL INSTALLATIONS OF BUILDINGS –
Part 5-53: Selection and erection of electrical equipment –
Isolation, switching and control
530 Introduction
530.1 Scope
This part of IEC 60364 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.
530.2 Normative references
The following normative documents contain provisions which, through reference in this text,
constitute provisions of this part of IEC 60364. For dated references, subsequent amend-
ments to, or revisions of, any of these publications do not apply. However, parties to
agreements based on this part of IEC 60364 are encouraged to investigate the possibility of
applying the most recent editions of the normative documents indicated below. For undated
references, the latest edition of the normative document referred to applies. Members of
IEC and ISO maintain registers of currently valid International Standards.
IEC 60038, IEC standard voltages
IEC 60269-3:1987, Low-voltage fuses – Part 3: Supplementary requirements for fuses for use
by unskilled persons (fuses mainly for household and similar applications)
IEC 60364-4-41:2001 2005, Electrical installations of buildings – IEC 60364-4-41: Protection
for safety – Protection against electric shock
IEC 60364-4-42:2001, Electrical installations of buildings – Part 4-42: Protection for safety –
Protection against thermal effects
IEC 60364-4-43:2001 2008, Electrical installations of buildings – Part 4-43: Protection for
safety – Protection against overcurrent
IEC 60364-4-44:2001 2007, Electrical installations of buildings – Part 4-44: Protection for
safety – Protection against voltage disturbances and electromagnetic disturbances
IEC 60364-5-54, Low-voltage electrical installations – Part 5-54: Selection and erection of
electrical equipment – Earthing arrangements and protective conductors
IEC 60364-6-61:2001, Electrical installations of buildings – Part 6-61: Verification – Initial
verification
IEC 60364-7-705:1984, Electrical installations of buildings – Part 7: Requirements for special
installations or locations – Section 705: Electrical installations of agricultural and horticultural
premises
IEC 60664-1:1992, Insulation coordination for equipment within low-voltage systems – Part 1:
Principles, requirements and tests
IEC 61008-1:1996 2010, Residual current operated circuit-breakers without integral
overcurrent protection for household and similar uses (RCCBs) – Part 1: General rules

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IEC 61009:1996, Residual current operated circuit-breakers with integral overcurrent
protection for household and similar uses (RCBOs) Part 1: General rules
IEC 61024-1:1990, Protection of structures against lightning – Part 1: General principles
IEC 61312-1:1995, Protection against lightning electromagnetic impulse – Part 1: General
principles
IEC/TS 61312-2:1999, Protection against lightning electromagnetic impulse (LEMP) – Part 2:
Shielding of structures, bonding inside structures and earthing
IEC/TS 61312-3:2000, Protection against lightning electromagnetic impulse – Part 3:
Requirements of surge protective devices (SPDs)
IEC 61643-1:1998, Surge-protective device connected to low-voltage power distribution
systems – Part 1: Performance requirements and testing methods
IEC 61643-1, amendment 1 (2001)
IEC 61643-11:2011, Low-voltage surge protective devices – Part 11: Surge protective devices
connected to low-voltage power systems – Requirements and test methods
IEC 61643-12:2008, Low-voltage surge protective devices – Part 12: Surge protective devices
connected to low-voltage power distribution systems – Part 1: Performance requirements and
testing methods Selection and application principles
IEC 62305 (all parts), Protection against lightning
IEC 62305-1, Protection against lightning – Part 1: General principles
IEC 62305-2, Protection against lightning – Part 2: Risk management
IEC 62305-4, Protection against lightning – Part 4: Electrical and electronic systems within
structures
530.3 (530) General and common requirements
This part of IEC 60364 shall provide compliance with the measures of protection for safety,
the requirements for proper functioning for intended use of the installation, and the
requirements appropriate to the external influences foreseen. Every item of equipment shall
be selected and erected so as to allow compliance with the rules stated in the following
clauses of this part and the relevant rules in other parts of this standard.
The requirements of this part are supplementary to the common rules given in IEC 60364-5-51.
530.3.1 (530.1) The moving contacts of all poles of multipole devices shall be so coupled
mechanically that they make and break substantially together, except that contacts solely
intended for the neutral may close before and open after the other contacts.
530.3.2 (530.2) Except as provided in 536.2.2.7, in multiphase circuits, single-pole devices
shall not be inserted in the neutral conductor.
In single-phase circuits single-pole devices shall not be inserted in the neutral conductor,
unless a residual current device complying with the rules of 413.1 of IEC 60364-4-41 is
provided on the supply side.
________
To be published.
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530.3.3 (530.3) Devices embodying more than one function shall comply with all the
requirements of this part appropriate to each separate function.
531 Devices for protection against indirect contact by automatic
disconnection of supply
531.1 Overcurrent protective devices
531.1.1  TN systems
In TN systems overcurrent protective devices shall be selected and erected according to the
conditions specified in 434.2 and 431 and in 533.3 for devices for protection against short-
circuit, and shall satisfy the requirements of 413.1.3.3.
531.1.2  TT systems
Under consideration.
531.1.3  IT systems
Where exposed-conductive-parts are interconnected, overcurrent protective devices for
protection in the event of a second fault shall comply with 531.1.1 taking into account the
requirements of 413.1.5.5 of IEC 60364-4-41.
531.2 Residual current protective devices
531.2.1  General conditions of installation
Residual current protective devices in d.c. systems shall be specially designed for detection
of d.c. residual currents, and to break circuit currents under normal conditions and fault
conditions.
531.2.1.1 A residual current protective device shall ensure the disconnection of all live
conductors in the circuit protected. In TN-S systems, the neutral need not be disconnected if
the supply conditions are such that the neutral conductor can be considered to be reliably at
earth potential.
NOTE The conditions for verification that the neutral conductor is reliably at earth potential are under
consideration.
531.2.1.2 No protective conductor shall pass through the magnetic circuit of a residual
current protective device.
531.2.1.3 Residual current protective devices shall be so selected, and the electrical circuits
so subdivided, that any earth-leakage current which may be expected to occur during normal
operation of the connected load(s) will be unlikely to cause unnecessary tripping of the
device.
NOTE Residual current protective devices may operate at any value of residual current in excess of 50 % of the
rated operating current.
531.2.1.4 Influence of d.c. components
Under consideration.
531.2.1.5 The use of a residual current protective device associated with circuits not having
a protective conductor, even if the rated operating residual current does not exceed 30 mA,
shall not be considered as a measure sufficient for protection against indirect contact.

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531.2.2  Selection of devices according to their method of application
531.2.2.1 Residual current protective devices may or may not have an auxiliary source,
taking into account the requirements of 531.2.2.2.
NOTE The auxiliary source may be the supply system.
531.2.2.2 The use of residual current protective devices with an auxiliary source not
operating automatically in the case of failure of the auxiliary source is permitted only if one of
the two following conditions is fulfilled:
– protection against indirect contact according to 413.1 of IEC 60364-4-41 is ensured even
in the case of failure of the auxiliary supply;
– the devices are installed in installations operated, tested and inspected by instructed
persons (BA4) or skilled persons (BA5).
531.2.3 TN systems
If for certain equipment or for certain parts of the installation, one or more of the conditions
stated in 413.1.3 cannot be satisfied, those parts may be protected by a residual current
protective device. In this case, exposed-conductive-parts need not be connected to the TN
earthing system protective conductor, provided that they are connected to an earth electrode
affording a resistance appropriate to the operating current of the residual current protective
device. The circuit thus protected is to be treated as a TT system and 413.1.4 applies.
If, however, no separate earth electrode exists, connection of the exposed-conductive-parts to
the protective conductor needs to be made on the source side of the residual current
protective device.
531.2.4 TT systems
If an installation is protected by a single residual current protective device, this shall be
placed at the origin of the installation, unless the part of the installation between the origin
and the device complies with the requirement for protection by the use of class II equipment
or equivalent insulation (see 413.2).
NOTE Where there is more than one origin, this requirement applies to each origin.
531.2.5  IT systems
Where protection is provided by a residual current protective device, and disconnection
following a first fault is not envisaged, the residual non-operating current of the device shall
be at least equal to the current which circulates on the first fault to earth of negligible
impedance affecting a phase conductor.
531.3 Insulation monitoring devices
NOTE Insulation monitoring devices may operate with an appropriate response time.
An insulation monitoring device provided in accordance with 413.1.5.4 is a device
continuously monitoring the insulation of an electrical installation. It is intended to indicate a
significant reduction in the insulation level of the installation to allow the cause of this
reduction to be found before the occurrence of a second fault, and thus avoid disconnection of
the supply.
Accordingly, it is set at a value below that specified in 612.3 of IEC 60364-6-61 appropriate to
the installation concerned.
Insulation monitoring devices shall be so designed or installed that it shall be possible to
modify the setting only by the use of a key or a tool.

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532 Devices for protection against thermal effects
Under consideration.
NOTE Pending this consideration, reference should be made to 422.3.10 of IEC 60364-4-42 and 705.422 of
IEC 60364-7-705.
533 Devices for protection against overcurrent
533.1 General requirements
533.1.1 Fuse bases using screw-in fuses shall be connected so that the centre contact is on
the supply side of the fuse base.
533.1.2 Fuse bases for plug-in fuse carriers shall be arranged so as to exclude the
possibility of the fuse carrier making contact between conductive parts belonging to two
adjacent fuse bases.
533.1.3 Fuses having fuse-links likely to be removed or placed by persons other than
instructed (BA4) or skilled persons (BA5), shall be of a type which complies with the safety
requirements of IEC 60269-3.
Fuses or combination units having fuse-links likely to be removed and replaced only by instructed
persons (BA4) or skilled persons (BA5), shall be installed in such a manner that it is ensured
that the fuse-links can be removed or placed without unintentional contact with live parts.
533.1.4 Where circuit-breakers may be operated by persons other than instructed persons
(BA4) or skilled persons (BA5), they shall be so designed or installed that it shall not be possible
to modify the setting of the calibration of their overcurrent releases without a deliberate act
involving the use of a key or tool, and resulting in a visible indication of their setting or calibration.
533.2 Selection of devices for protection of wiring systems against overloads
The nominal current (or current setting) of the protective device shall be chosen in
accordance with 433.1.
NOTE  In certain cases, to avoid unintentional operation, the peak current values of the loads have to be taken
into consideration.
In the case of a cyclic load, the values of I and I shall be chosen on the basis of values of I
n
2 B
and I for the thermally equivalent constant load
z
where
l is the current for which the circuit is designed;
B
I is the continuous current-carrying capacity of the cable;
z
I is the nominal current of the protective device;
n
I is the current ensuring effective operation of the protective device.
533.3 Selection of devices for protection of wiring systems against short circuits
The application of the rules of part 4-43 for short-circuit duration up to 5 s shall take into
account minimum and maximum short-circuit conditions.
Where the standard covering a protective device specifies both a rated service short-circuit
breaking capacity, and a rated ultimate short-circuit breaking capacity, it is permissible to
select the protective device on the basis of the ultimate short-circuit breaking capacity for the
maximum short-circuit conditions. Operational circumstances may, however, make it desirable
to select the protective device on the service short-circuit breaking capacity, e.g. where a
protective device is placed at the origin of the installation.

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534 Devices for protection against electromagnetic and voltage disturbances
transient overvoltages
534.1 (534)  Devices for protection against overvoltage General
534.1.1  General
This clause contains provisions for the application of voltage limitation to obtain an insulation
coordination in the cases described in IEC 60364-4-43 IEC 60364-4-44, IEC 60664-1,
IEC 62305-1, IEC 62305-4 and IEC 61643-12.
This clause focuses mainly on the requirements for the selection and erection of SPDs of
installations of buildings to obtain a limitation of transient overvoltages of atmospheric origin
transmitted by the supply distribution system and against switching overvoltages generated by
the equipment within the installation for protection against transient overvoltages where
required by Clause 443 of IEC 60364-4-44:2007, the IEC 62305 series, or as otherwise
specified.
This clause does not take into account:
– surge protective components which may be incorporated in the appliances connected to
the installation;
– portable SPDs.
NOTE Further information can be found in IEC 61643-12.
This clause applies to a.c. power circuits. As far as it is applicable, the requirements of this
clause may be followed for d.c. power circuits.
534.2 Erection of surge protective devices in building installations Void
534.2.1 When required or otherwise specified in accordance with IEC 60364-4-44, surge
protective devices shall be installed near the origin of the installation or in the main
distribution assembly, closest to the origin of the installation.
NOTE 1  In some cases, in order to obtain complete protection of the installation, additional surge protective
devices, which are not considered in this part, may be necessary.
NOTE 2  Surge protective devices located elsewhere in the installation may also provide sufficient protection.
534.2.2 When required or otherwise specified in accordance with IEC 60364-4-44, surge
protective devices shall be installed (see also annexes A, B and C):
– if the neutral conductor is earthed at or near the origin of the installation or if there is no
neutral conductor:
• between unearthed line conductors and either the main earthing terminal or the main
protective conductor bar, whichever route is shorter;
– if the neutral conductor is not earthed at or near the origin of the installation:
• between each line conductor and either the main earthing terminal or the main
protective conductor bar, and
• between the neutral conductor and either the main earthing terminal or the protective
conductor bar, whichever route is shorter. (As an alternative, see figure B.2.)
NOTE 1  If a line conductor is earthed, it is considered to be equivalent to a neutral conductor.
NOTE 2  In TT and TN systems, this requirement does not exclude a supplementary differential mode protection.
534.2.3 Selection of surge protective devices (SPDs)
534.2.3.1  The maximum continuous operating voltage U of SPDs shall be not less than the
c
maximum actual continuous voltage between the terminals of the SPD.

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In TT systems, according to figure B.1, U shall be at least 1,5 U .
c o
In TN systems and TT systems, according to figure B.2, U shall be at least 1,1 U .
c o
In IT systems, U shall be at least as high as the line-to-line voltage U.
c
NOTE 1  U is the line to neutral voltage of the low voltage system.
o
NOTE 2  In extended IT systems, higher values of U may be necessary.
c
534.2.3.2 The surge protective devices and its series protective means shall withstand
safely the temporary overvoltages (see IEC 60364-4-44).
534.2.3.3 The surge protective devices shall comply with IEC 61643-1, additional
information regarding selection and application should be found in IEC 61643-12.
534.2.3.4 If the surge protective device is installed at the origin of an electrical installation
supplied by the public distribution system, the rated discharge current shall not be less than 5 kA.
NOTE 1  More severe conditions of exposure may lead to the choice of an higher value.
NOTE 2  In presence of a lightning protection system, the discharge current will be substantially higher and an
assessment will lead to the choice of a higher rated discharge current for the SPD. For further information refer to
IEC 61643-12.
534.2.3.5 The protection level of the SPD shall be chosen according to 443.3.2 of
IEC 60364-4-44.
NOTE 1  The surge withstand level of some equipment may also need to be taken into account.
NOTE 2  Additional SPDs may be necessary closer to sensitive equipment, if not already included in the
equipment.
534.2.3.6 The possible cascading of SPDs in the installation shall be taken into account.
The SPD manufacturers shall provide in their documentation the measures to be taken to
facilitate their mutual coordination, in particular for the SPDs of a protective level different
from that provided at the origin of the electrical installation and intended to protect current-
using equipment incorporating sensitive electronic circuits.
534.2.4 Surge protective devices shall be erected according to the manufacturer's
instructions in order to avoid any fire or explosion risk in case of overloading of surge
protective devices (see IEC 60364-4-42). SPDs shall not be installed in locations classified
BE2 or BE3 without appropriate protective means.
534.2.5 In order to avoid any restriction of the availability of electricity supply in the
protected installation due to failures of surge protective devices, protective means against
overcurrents and fault currents to earth, either built-in or in series with the surge protective
device, shall be applied unless in the manufacturers´ instructions, it is stated that additional
protection means are not necessary.
534.2.6 Protection against indirect contact, as defined in IEC 60364-4-41, shall remain
effective in the protected building installation even in case of failures of surge protective
devices.
NOTE 1  In TN-systems, this may in general be fulfilled by the overcurrent device on the supply side of the surge
protective device.
NOTE 2  In TT-systems, this may be fulfilled by installing the surge protective device on the load side of a residual
current device (RCD).
NOTE 3  Other m
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