IEC 60364-5-53

Electrical installations of buildings - Part 5-53: Selection and erection of electrical equipment - Isolation, switching and control

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 consolidated version consists of the third edition (2001)    and its amendment 1 (2002). Therefore, no need to order amendment in addition to this publication.

Installations électriques des bâtiments - Partie 5-53: Choix et mise en oeuvre des matériels électriques - Sectionnement, coupure et commande

Traite des prescriptions générales relatives au sectionnement, à la coupure et à la commande, ainsi que des prescriptions relatives au choix et à la mise en oeuvre des dispositifs assurant ces fonctions.[
] Cette version consolidée comprend la troisième édition (2001) et son amendement 1 (2002). Il n'est donc pas nécessaire de commander  l'amendement avec cette publication.

Električne inštalacije zgradb – 5-53. del: Izbira in namestitev električne opreme – Ločevanje, stikanje in krmiljenje – Dopolnilo A1

General Information

• Status: Not Published
• ICS: 29.130 - Switchgear and controlgear
• ICS: 91.140.50 - Electricity supply systems
• Technical Committee: TC 64 - Electrical installations and protection against electric shock
• Current Stage: PPUB - Publication issued
• Start Date: 24-Jun-2002
• Ref Project: SIST IEC 60364-5-53:2006/A1:2006 - Electrical installations of buildings - Part 5-53: Selection and erection of electrical equipment - Isolation, switching and control

Standards Content (Sample)

NORME CEI
INTERNATIONALE IEC
60364-5-53
INTERNATIONAL
Troisième édition
STANDARD
Third edition
2001-08
Installations électriques des bâtiments –
Partie 5-53:
Choix et mise en œuvre des matériels électriques –
Sectionnement, coupure et commande
Electrical installations of buildings –
Part 5-53:
Selection and erection of electrical equipment –
Isolation, switching and control
 IEC 2001 Droits de reproduction réservés  Copyright - all rights reserved
Aucune partie de cette publication ne peut être reproduite ni No part of this publication may be reproduced or utilized in
utilisée sous quelque forme que ce soit et par aucun procédé, any form or by any means, electronic or mechanical,
électronique ou mécanique, y compris la photocopie et les including photocopying and microfilm, without permission in
microfilms, sans l'accord écrit de l'éditeur. writing from the publisher.
International Electrotechnical Commission 3, rue de Varembé Geneva, Switzerland
Telefax: [phone] e-mail: [e-mail] IEC web site http://www.iec.ch
CODE PRIX
Commission Electrotechnique Internationale
U
PRICE CODE
International Electrotechnical Commission
Pour prix, voir catalogue en vigueur
For price, see current catalogue

---------------------- Page: 1 ----------------------

60364-5-53 © IEC:2001 – 3 –
CONTENTS
FOREWORD . 5
530 Introduction . 7
530.1 Scope. 7
530.2 Normative references . 7
530.3 (530) General and common requirements . 9
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 . 11
531.3 Insulation monitoring devices. 13
532 Devices for protection against thermal effects. 13
533 Devices for protection against overcurrent . 13
533.1 General requirements . 13
533.2 Selection of devices for protection of wiring systems against overloads . 15
533.3 Selection of devices for protection of wiring systems against short circuits . 15
534 Devices for protection against electromagnetic and voltage disturbances . 15
534.1 (534) Devices for protection against overvoltage . 15
534.2 Erection of surge protective devices in building installations . 15
534.3 (535) Devices for protection against undervoltage . 21
535 (539) Co-ordination of various protective devices . 21
535.1 (539.1) Discrimination between overcurrent protective devices . 21
535.2 (539.2) Association of residual current protective devices with overcurrent
protective devices. 21
535.3 (539.3) Discrimination between residual current protective devices. 21
536 (46) Isolation and switching . 23
536.0 (460) Introduction.23
536.1 (461) General . 23
536.2 (462) Isolation . 23
536.3 (463) Switching off for mechanical maintenance . 27
536.4 (464) Emergency switching. 29
536.5 (465) Functional switching (control) . 33
Annex A (informative) Installation of surge protective devices in TN-systems . 37
Annex B (informative) Installation of surge protective devices in TT-systems . 39
Annex C (informative) Installation of surge protective devices in IT-systems . 43
Annex D (informative) IEC 60364 – Parts 1 to 6: Restructuring. 45
Bibliography . 53
Figure A.1 – SPDs in TN-systems . 37
Figure B.1 – SPDs on the load side of RCD. 39
Figure B.2 – SPDs on the supply side of RCD . 41
Figure C.1 – SPDs on the load side of RCD . 43
Table 53A – Impulse-withstand voltage as a function of the nominal voltage . 25
Table D.1 – Relationship between restructured and original parts. 45
Table D.2 – Relationship between new and old clause numbering . 49

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60364-5-53 © IEC:2001 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
––––––––––
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).
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).
This publication has been drafted, as close as possible, in accordance with the ISO/IEC
Directives, Part 3.
Annexes A, B, C and D are for information only.
The committee has decided that the contents of this publication will remain unchanged
until 2005. At this date, the publication will be
reconfirmed;
withdrawn;
replaced by a revised edition, or
amended.

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60364-5-53 © IEC:2001 – 7 –
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 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 61009:1996, 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

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60364-5-53 © IEC:2001 – 9 –
IEC 61312-1:1995, Protection against lightning electromagnetic impulse – Part 1: General
principles
IEC 61643-1:1998, Surge-protective device connected to low-voltage power distribution
systems – Part 1: Performance requirements and testing methods
IEC 61643-12, Surge-protective device connected to low-voltage power distribution systems –
1
Part 1: 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.
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.
________
1
 To be published.

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60364-5-53 © IEC:2001 – 11 –
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).
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.

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60364-5-53 © IEC:2001 – 13 –
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.
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.

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60364-5-53 © IEC:2001 – 15 –
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.
2
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.
534 Devices for protection against electromagnetic and voltage disturbances
534.1 (534)  Devices for protection against overvoltage
534.1.1  General
This clause contains provisions for the application of voltage limitation to obtain an insulation
coordination according to IEC 60364-4-43 and IEC 60664-1.
This clause gives the requirements for the erection and selection of surge protective devices
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.
534.2 Erection of surge protective devices in building installations
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.

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60364-5-53 © IEC:2001 – 17 –
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.
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.

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60364-5-53 © IEC:2001 – 19 –
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 means, such as surge protective device-disconnectors, are under consideration.
534.2.7 If surge protective devices are installed in accordance with 534.2.1 and are on the
load side of a residual current device, an S-type RCD with an immunity to surge currents of at
least 3 kA (8/20 μs) shall be used.
534.2.8 If a lightning protection system is installed, additional requirements for surge
protective devices shall be applied (see IEC 61024-1 and IEC 61312-1).
534.2.9 Indication that the SPD no longer provides overvoltage protection shall be provided:
– either by the SPD itself; or
– by a separate protective device such as described in 534.2.5.
NOTE  If there is a loss of overvoltage protection, circuits supplying equipment sensitive to surges may need
further provisions.
534.2.10 In order to achieve an optimum overvoltage protection, all connecting conductors
of surge protective devices shall be as short as possible (preferably not exceeding 0,5 m for
the total length).
NOTE 1  Increasing the length of connecting conductors of surge protective devices reduces the effectiveness of
overvoltage protection. Using outgoing and return conductors in a V shape is a valid method of connection not
reducing the effectiveness of SPDs.
NOTE 2  Connecting conductors are the conductors from the line conductor to the surge protective device and
from the surge protect
...

NORME CEI
INTERNATIONALE IEC
60364-5-53
INTERNATIONAL
2001
STANDARD
AMENDEMENT 1
AMENDMENT 1
2002-04
Amendement 1
Installations électriques des bâtiments –
Partie 5-53:
Choix et mise en oeuvre des matériels
électriques – Sectionnement, coupure
et commande
Amendment 1
Electrical installations of buildings –
Part 5-53:
Selection and erection of electrical
equipment – Isolation, switching and control
 IEC 2002 Droits de reproduction réservés  Copyright - all rights reserved
International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland
Telephone: [phone] Telefax: [phone] E-mail: [e-mail]  Web: www.iec.ch
CODE PRIX
N
Commission Electrotechnique Internationale
PRICE CODE
International Electrotechnical Commission
Международная Электротехническая Комиссия
Pour prix, voir catalogue en vigueur
For price, see current catalogue

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60364-5-53 Amend. 1  IEC:2002 – 3 –
FOREWORD
This amendment has been prepared by IEC technical committee 64: Electrical installations and
protection against electric shock.
The text of this amendment is based on the following documents:
FDIS Report on voting
64/1226/FDIS 64/1243/RVD
Full information on the voting for the approval of this amendment can be found in the report on
voting indicated in the above table.
The committee has decided that the contents of the base publication and its amendments will
remain unchanged until 2003. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
_____________
Page 7
530.2 Normative references
Add the following references to the existing list:
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, amendment 1 (2001)

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60364-5-53 Amend. 1  IEC:2002 – 5 –
Page 15
Replace the existing clause 534 by the following new clause 534.
534 Devices for protection against overvoltages
534.1 General
This clause contains provisions for the application of voltage limitation to obtain an insulation
coordination in the cases described in IEC 60364-4-44, IEC 60664-1, IEC 61312-2 and
IEC 61643-12.
This clause gives the requirements for the selection and erection of
– surge protective devices (SPDs) for electrical installations of buildings to obtain a limitation
of transient overvoltages of atmospheric origin transmitted via the supply distribution
system and against switching overvoltages;
– SPDs for the protection against transient overvoltages caused by direct lightning strokes or
lightning strokes in the vicinity of buildings, protected by a lightning protection system.
This clause does not take into account surge protective components which may be
incorporated in the appliances connected to the installation. The presence of such components
may modify the behaviour of the main surge protective device of the installation and may need
an additional coordination.
This clause applies to a.c. power circuits. For d.c. power circuits, the requirements in this
clause may be applied as far as is useful. For special applications, other or additional
requirements may be necessary in the relevant part 7 of IEC 60364.
534.2 Selection and erection of SPDs in building installations
534.2.1 Use of SPDs
IEC 60364-4-44, clause 443, includes protection against overvoltages of atmospheric origin
(caused by indirect, distant lightning strokes) and switching overvoltages. This protection is
normally provided by the installation of test class II SPDs and if necessary test class III SPDs.
When required in accordance with IEC 60364-4-44 or otherwise specified, SPDs shall be
installed near the origin of the installation or in the main distribution assembly, closest to the
origin of the installation inside the building.
IEC 61312-1 includes protection against the effects of direct lightning strokes or strokes near
to the supply system. IEC 61312-3 describes the correct selection and application of SPDs
according to the Lightning Protection Zones (LPZ) concept. The LPZ concept describes the
installation of test class I, test class II and test class III SPDs.
When required in accordance with IEC 61312-1 or otherwise specified, SPDs shall be installed
at the origin of the installation.
Additional SPDs may be necessary to protect sensitive equipment. Such SPDs shall be
coordinated with the SPDs installed upstream (see 534.2.3.6).
In the case where SPDs are part of the fixed electrical installation, but not mounted inside a
distribution board (e.g. in a socket outlet), their presence shall be indicated by a label on or as
near as is reasonably possible to the origin of the circuit under consideration.

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60364-5-53 Amend. 1  IEC:2002 – 7 –
534.2.2 Connection of SPDs
Surge protective devices at or near the origin of the installation shall be connected at least
between the following points (see annexes A, B and C):
a) if there is a direct connection between the neutral conductor and the PE at or near the
origin of the installation or if there is no neutral conductor:
between each line conductor and either the main earthing terminal or the main protective
conductor, whichever is the shortest route;
NOTE The impedance connecting the neutral to the PE in IT systems is not considered as a connection
b) if there is no direct connection between the neutral conductor and the PE at or near the
origin of the installation, then either
between each line conductor and either the main earthing terminal or the main protective
conductor, and between the neutral conductor and either the main earthing terminal or the
protective conductor, whichever is the shortest route – connection type 1;
or
between each line conductor and the neutral conductor and between the neutral conductor
and either the main earthing terminal or the protective conductor, whichever route is shorter
– connection type 2 .
NOTE If a line conductor is earthed, it is considered to be equivalent to a neutral conductor for the application of
this subclause.
SPDs at or near the origin of the installation are, in general, installed as shown in annexes A
to C and according to table 53B:
Table 53B – Connection of surge protective devices
dependent on system configuration
System configuration at the installation point of SPD
TT TN-C TN-S IT with distributed neutral
SPDs
Installation Installation Installation IT without
connected
according to according to according to distributed
between
neutral
Connection Connection Connection Connection Connection Connection
type 1 type 2 type 1 type 2 type 1 type 2
each line
conductor + NA + + NA
• • •
and neutral
conductor
each line NA NA NA NA
• • • •
conductor
and PE
conductor
neutral •• NA •• •• NA
conductor
and PE
conductor
each line NA NA NA NA NA NA NA
•
conductor
and PEN
conductor
line ++ + + ++ + +
conductors
• : mandatory
NA: not applicable
+: optional, in addition

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60364-5-53 Amend. 1  IEC:2002 – 9 –
534.2.3 Selection of surge protective devices (SPDs)
The SPDs shall comply with IEC 61643-1. Additional information regarding selection and
application is given in IEC 61643-12.
534.2.3.1 Selection with regard to protection level (U )
p
If clause 443 of IEC 60364-4-44 requires SPDs, the protection level U of SPDs shall be selected
p
in accordance with impulse withstand voltage category II of table 44B (IEC 60364-4-44).
If IEC 61312-1 requires SPDs for the protection against overvoltages caused by direct lightning
strokes, the protection level of these SPDs shall also be selected in accordance with impulse
withstand voltage category II of table 44B in IEC 60364-4-44.
For example in 230/400 V installations, the protection level U shall not exceed 2,5 kV.
p
When connection type 2 according to 534.2.2 is used, the above requirements also apply to the
total protection level between line conductors and PE.
When the required protection level cannot be reached with a single set of SPDs, additional,
coordinated SPDs shall be applied to ensure the required protection level.
534.2.3.2 Selection with regard to continuous operating voltage (U )
c
The maximum continuous operating voltage U of SPDs shall be equal to or higher than shown
c
in the following table 53C.
Table 53C – Minimum required U of the SPD dependent on
c
supply system configuration
System configuration of distribution network
SPDs connected
TT TN-C TN-S IT with IT without
between
distributed distributed
neutral neutral
line conductor 1,1 U NA 1,1 U 1,1 U NA
o o o
and neutral conductor
each line conductor and PE conductor 1,1 U NA 1,1 U Line-to-line
o o
a
3 U
o
a
voltage
a a a
neutral conductor NA NA
U U U
o o o
and PE conductor
each line conductor and PEN conductor
NA 1,1 U NA NA NA
o
NA: not applicable
NOTE 1 U is the line-to-neutral voltage of the low-voltage system.
o
NOTE 2 This table is based on IEC 61643-1 amendment 1.
a
These values are related to worst case fault conditions, therefore the tolerance of 10 % is not taken into account.

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60364-5-53 Amend. 1  IEC:2002 – 11 –
534.2.3.3 Selection with regard to temporary overvoltages (TOVs)
The SPDs selected according to 534.2.3 shall withstand the temporary overvoltages due to
faults within low-voltage systems (see clause 442 of IEC 60364-4-44).
This is confirmed by the selection of SPDs which comply with the relevant test requirements of
7.7.6 of IEC 61643-1.
To fail safely in case of TOVs due to earth faults within the high-voltage system (see IEC
60364-4-44, clause 442), the SPDs connected to the PE shall pass the test of IEC 61643-1
subclause 7.7.4.
In addition, SPDs installed in location 4a according to figure B.2 shall withstand such TOVs as
defined in test of IEC 61643-1 subclause 7.7.4.
NOTE 1 Appropriate pass criteria are under consideration to define the meaning of withstand.
NOTE 2 The loss of neutral is not covered by these requirements. Though there is currently no specific test
in IEC 61643-1, SPDs are expected to fail safely.
534.2.3.4 Selection with regard to discharge current (I ) and impulse current (I )
n imp
If IEC 60364-4-44 clause 443 requires SPDs, the nominal discharge current I shall not be less
n
than 5 kA 8/20 for each mode of protection.
In case of installation according to 534.2.2 connection type 2, the nominal discharge current I
n
for the surge protective device connected between the neutral conductor and the PE shall not
be less than 20 kA 8/20 for three-phase systems and 10 kA 8/20 for single-phase systems.
If IEC 61312-1 requires SPDs, the lightning impulse current I according to IEC 61643-1 shall
imp
be calculated according to IEC 61312-1. Further information is given in IEC 61643-12. If the
current value cannot be established, the value of I shall not be less than 12,5 kA for each
imp
mode of protection.
In case of an installation according to 534.2.2 connection type 2, the lightning impulse current
I for the surge protective device connected between the neutral conductor and the PE shall
imp
be calculated similarly to the above mentioned standards. If the current value cannot be
established the value of I shall not be less than 50 kA for three-phase systems and 25 kA for
imp
single-phase systems.
When a single SPD is used for protection according to both IEC 61312-1 and clause 443 of
IEC 60364-4-44, the rating of I and of I shall be in agreement with the above values.
n imp
534.2.3.5 Selection with regard to the expected short-circuit current
The short-circuit withstand of the SPDs (in case of SPD failure) together with the specified
associated (internal or external) overcurrent protective device shall be equal to or higher than
the maximum short-circuit current exp
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