SIST IEC 60364-4-41:2006
(Main)Low-voltage electrical installations - Part 4-41: Protection for safety - Protection against electric shock
Low-voltage electrical installations - Part 4-41: Protection for safety - Protection against electric shock
Specifies essential requirements regarding protection against electric shock, including basic protection (protection against direct contact) and fault protection (protection against indirect contact) of persons and livestock. It deals also with the application and co-ordination of these requirements in relation to external influences.[
]Requirements are also given for the application of additional protection in certain cases. Has the status of a group safety publication in accordance with IEC Guide 104.
Installations électriques à basse tension - Partie 4-41: Protection pour assurer la sécurité - Protection contre les chocs électriques
Spécifie des exigences essentielles relatives à la protection contre les chocs électriques comprenant la protection principale (protection en fonctionnement normal) et la protection en cas de défaut (protection dans des conditions de défaut) des personnes et des animaux domestiques. Elle traite de l'application et de la coordination de ces exigences en liaison avec les conditions des influences externes.[
]Les exigences relatives à la protection complémentaire sont données dans certains cas. A le statut d'une publication groupée de sécurité conformément au Guide 104 de la CEI.
Nizkonapetostne električne inštalacije – 4-41. del: Zaščitni ukrepi – Zaščita pred električnim udarom
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST IEC 60364-4-41:2006
01-september-2006
1L]NRQDSHWRVWQHHOHNWULþQHLQãWDODFLMH±GHO =DãþLWQLXNUHSL±=DãþLWDSUHG
HOHNWULþQLPXGDURP
Low-voltage electrical installations - Part 4-41: Protection for safety - Protection against
electric shock
Ta slovenski standard je istoveten z:
ICS:
13.260 9DUVWYRSUHGHOHNWULþQLP Protection against electric
XGDURP shock
91.140.50 Sistemi za oskrbo z elektriko Electricity supply systems
SIST IEC 60364-4-41:2006 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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INTERNATIONAL IEC
STANDARD 60364-4-41
Fifth edition
2005-12
GROUP SAFETY PUBLICATION
Low-voltage electrical installations –
Part 4-41:
Protection for safety –
Protection against electric shock
© IEC 2005 Copyright - all rights reserved
No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical,
including photocopying and microfilm, without permission in writing from the publisher.
International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland
Telephone: +41 22 919 02 11 Telefax: +41 22 919 03 00 E-mail: inmail@iec.ch Web: www.iec.ch
PRICE CODE
V
Commission Electrotechnique Internationale
International Electrotechnical Commission
МеждународнаяЭлектротехническаяКомиссия
For price, see current catalogue
---------------------- Page: 2 ----------------------
60364-4-41 IEC:2005 – 3 –
CONTENTS
FOREWORD.5
410 Introduction .9
410.1 Scope .11
410.2 Normative references .11
410.3 General requirements .13
411 Protective measure: automatic disconnection of supply .15
411.1 General .15
411.2 Requirements for basic protection .17
411.3 Requirements for fault protection .17
411.4 TN systems.21
411.5 TT systems.23
411.6 IT systems.25
411.7 Functional extra-low voltage (FELV) .29
412 Protective measure: double or reinforced insulation.31
412.1 General .31
412.2 Requirements for basic protection and fault protection (protection against
indirect contact).33
413 Protective measure: electrical separation .37
413.1 General .37
413.2 Requirements for basic protection .37
413.3 Requirements for fault protection .37
414 Protective measure: extra-low-voltage provided by SELV and PELV.39
414.1 General .39
414.2 Requirements for basic protection and fault protection .39
414.3 Sources for SELV and PELV.41
414.4 Requirements for SELV and PELV circuits.41
415 Additional protection.43
415.1 Additional protection: residual current protective devices (RCDs) .45
415.2 Additional protection: supplementary protective equipotential bonding.45
Annex A (normative) Provisions for basic protection (protection against direct contact) .47
Annex B (normative) Obstacles and placing out of reach .51
Annex C (normative) Protective measures for application only when the installation is
controlled or under the supervision of skilled or instructed persons.55
Annex D (informative) Correspondence between IEC 60364-4-41(2001) and the present
standard.…. .61
Bibliography.65
Figure B.1 – Zone of arm's reach .53
Table 41.1 – Maximum disconnection times .19
Table D.1 – Correspondence between IEC 60364-4-41:2001 and the present standard .61
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60364-4-41 IEC:2005 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
LOW-VOLTAGE ELECTRICAL INSTALLATIONS –
Part 4-41: Protection for safety –
Protection against electric shock
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60364-4-41 has been prepared by IEC technical committee 64:
Electrical installations and protection against electric shock.
This fifth edition cancels and replaces the fourth edition, published in 2001, and constitutes a
technical revision.
The main changes with respect to the previous edition are listed below:
– adoption of IEC 61140 terminology;
– layout rationalized on basis of complete protective measures (i.e. appropriate practical
combinations of protective provision in normal service (direct contact protection) and
protective provision in case of a fault (indirect contact protection);
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60364-4-41 IEC:2005 – 7 –
– requirements of 471 and 481, which were included in the fourth edition have been
rationalized
– disconnection requirements for TT systems clarified;
– IT systems considered more fully;
– requirements in certain cases for additional protection of socket-outlets by means of a
30 mA RCD, where the protective measure is automatic disconnection of supply.
The text of this standard is based on the following documents:
FDIS Report on voting
64/1489/FDIS 64/1500/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
It has the status of a group safety publication in accordance with IEC Guide 104.
The Part 4 series comprises the following parts under the general title Low-voltage electrical
installations:
Part 4-41: Protection for safety – Protection against electric shock
Part 4-42: Protection for safety – Protection against thermal effects
Part 4-43: Protection for safety – Protection against overcurrent
Part 4-44: Protection for safety – Protection against voltage disturbances and electromagnetic
disturbances
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result 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.
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60364-4-41 IEC:2005 – 9 –
410 Introduction
This Part 4-41 of IEC 60364 deals with protection against electric shock as applied to
electrical installations. It is based on IEC 61140 which is a basic safety standard that applies
to the protection of persons and livestock. IEC 61140 is intended to give fundamental
principles and requirements that are common to electrical installations and equipment or are
necessary for their co-ordination.
The fundamental rule of protection against electric shock, according to IEC 61140, is that
hazardous-live-parts must not be accessible and accessible conductive parts must not be
hazardous live, neither under normal conditions nor under single fault conditions.
According to 4.2 of IEC 61140, protection under normal conditions is provided by basic
protective provisions and protection under single fault conditions is provided by fault
protective provisions. Alternatively, protection against electric shock is provided by an
enhanced protective provision, which provides protection under normal conditions and under
single fault conditions.
This standard has the status of a group safety publication (GSP) for protection against electric
shock.
In the fourth edition of IEC 60364 (2001):
– protection under normal conditions (now designated basic protection) was referred to as
protection against direct contact and
– protection under fault conditions (now designated fault protection) was referred to as
protection against indirect contact.
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60364-4-41 IEC:2005 – 11 –
LOW-VOLTAGE ELECTRICAL INSTALLATIONS –
Part 4-41: Protection for safety –
Protection against electric shock
410.1 Scope
Part 4-41 of IEC 60364 specifies essential requirements regarding protection against electric
shock, including basic protection (protection against direct contact) and fault protection
(protection against indirect contact) of persons and livestock. It deals also with the application
and co-ordination of these requirements in relation to external influences.
Requirements are also given for the application of additional protection in certain cases.
410.2 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 60364-5-52, Electrical installations of buildings – Part 5-52: Selection and erection of
)
1
electrical equipment – Wiring systems
IEC 60364-5-54, Electrical installations of buildings – Part 5-54: Selection and erection of
electrical equipment – Earthing arrangements, protective conductors and protective bonding
conductors
)
2
IEC 60364-6, Low-voltage electrical installations – Part 6: Verification
IEC 60439-1, Low-voltage switchgear and controlgear assemblies – Part 1: Type-tested and
partially type-tested assemblies
IEC 60449, Voltage bands for electrical installations of buildings
IEC 60614 (all parts), Conduits for electrical installations – Specification
IEC 61084 (all parts), Cable trunking and ducting systems for electrical installations
IEC 61140, Protection against electric shock – Common aspects for installation and equipment
IEC 61386 (all parts), Conduit systems for electrical installations
IEC 61558-2-6, Safety of power transformers, power supply units and similar – Part 2-6:
Particular requirements for safety isolating transformers for general use
IEC Guide 104, The preparation of safety publications and the use of basic safety publications
and group safety publications
———————
)
1
A new edition is currently under consideration.
)
2
To be published.
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60364-4-41 IEC:2005 – 13 –
410.3 General requirements
410.3.1 In this standard the following specification of voltages is intended unless otherwise
stated:
– a.c. voltages are r.m.s.;
– d.c. voltages are ripple-free.
Ripple-free is conventionally defined as an r.m.s. ripple voltage of not more than 10 % of the
d.c. component.
410.3.2 A protective measure shall consist of
– an appropriate combination of a provision for basic protection and an independent
provision for fault protection, or
– an enhanced protective provision which provides both basic protection and fault
protection.
Additional protection is specified as part of a protective measure under certain conditions of
external influences and in certain special locations (see the corresponding Part 7 of
IEC 60364).
NOTE 1 For special applications, protective measures which do not follow this concept are permitted (see 410.3.5
and 410.3.6).
NOTE 2 An example of an enhanced protective measure is reinforced insulation.
410.3.3 In each part of an installation one or more protective measures shall be applied,
taking account of the conditions of external influence.
The following protective measures generally are permitted:
– automatic disconnection of supply (Clause 411),
– double or reinforced insulation (Clause 412),
– electrical separation for the supply of one item of current-using equipment (Clause 413),
– extra-low-voltage (SELV and PELV) (Clause 414).
The protective measures applied in the installation shall be considered in the selection and
erection of equipment.
For particular installations see 410.3.4 to 410.3.9.
NOTE In electrical installations the most commonly used protective measure is automatic disconnection of supply.
410.3.4 For special installations or locations, the particular protective measures in the
corresponding Part 7 of IEC 60364 shall be applied.
410.3.5 The protective measures, specified in Annex B, i.e. the use of obstacles and placing
out of reach, shall only be used in installations accessible to
– skilled or instructed persons, or
– persons under the supervision of skilled or instructed persons.
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60364-4-41 IEC:2005 – 15 –
410.3.6 The protective measures, specified in Annex C, i.e.
– non-conducting location,
– earth-free local equipotential bonding,
– electrical separation for the supply of more than one item of current-using equipment,
may be applied only when the installation is under the supervision of skilled or instructed
persons so that unauthorized changes cannot be made.
410.3.7 If certain conditions of a protective measure cannot be met, supplementary
provisions shall be applied so that the protective provisions together achieve the same degree
of safety.
NOTE An example of the application of this rule is given in 411.7.
410.3.8 Different protective measures applied to the same installation or part of an
installation or within equipment shall have no influence on each other such that failure of one
protective measure could impair the other protective measures.
410.3.9 The provision for fault protection (protection against indirect contact) may be omitted
for the following equipment:
– metal supports of overhead line insulators which are attached to the building and are
placed out of arm’s reach;
– steel reinforced concrete poles of overhead lines in which the steel reinforcement is not
accessible;
– exposed-conductive-parts which, owing to their reduced dimensions (approximately
50 mm x 50 mm) or their disposition cannot be gripped or come into significant contact
with a part of the human body and provided that connection with a protective conductor
could only be made with difficulty or would be unreliable.
NOTE 1 This exemption applies, for example, to bolts, rivets, nameplates and cable clips.
NOTE 2 In the USA, all exposed-conductive-parts are bonded to the protective conductor.
– metal tubes or other metal enclosures protecting equipment in accordance with
Clause 412.
411 Protective measure: automatic disconnection of supply
411.1 General
Automatic disconnection of supply is a protective measure in which
– basic protection is provided by basic insulation of live parts or by barriers or enclosures, in
accordance with Annex A, and
– fault protection is provided by protective equipotential bonding and automatic
disconnection in case of a fault in accordance with 411.3 to 411.6.
NOTE 1 Where this protective measure is applied, Class II equipment may also be used.
Where specified, additional protection is provided by a residual current protective device
(RCD) with rated residual operating current not exceeding 30 mA in accordance with 415.1.
NOTE 2 Residual current monitors (RCMs) are not protective devices but they may be used to monitor residual
currents in electrical installations. RCMs produce an audible or audible and visual signal when a preselected value
of residual current is exceeded
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60364-4-41 IEC:2005 – 17 –
411.2 Requirements for basic protection
All electrical equipment shall comply with one of the provisions for basic protection (protection
against direct contact) described in Annex A or, where appropriate, Annex B.
411.3 Requirements for fault protection
411.3.1 Protective earthing and protective equipotential bonding
411.3.1.1 Protective earthing
Exposed-conductive-parts shall be connected to a protective conductor under the specific
conditions for each type of system earthing as specified in 411.4 to 411.6.
Simultaneously accessible exposed-conductive-parts shall be connected to the same earthing
system individually, in groups or collectively.
Conductors for protective earthing shall comply with IEC 60364-5-54.
Each circuit shall have available a protective conductor connected to the relevant earthing
terminal.
411.3.1.2 Protective equipotential bonding
In each building the earthing conductor, the main earthing terminal and the following
conductive parts shall be connected to the protective equipotential bonding:
– metallic pipes supplying services into the building, e.g. gas, water;
– structural extraneous-conductive-parts if accessible in normal use, metallic central heating
and air-conditioning systems.
– metallic reinforcements of constructional reinforced concrete, if reasonably practicable.
Where such conductive parts originate outside the building, they shall be bonded as close as
practicable to their point of entry within the building.
Conductors for protective equipotential bonding shall comply with IEC 60364-5-54.
Any metallic sheath of telecommunication cables shall be connected to the protective
equipotential bonding, taking account of the requirements of the owners or operators of these
cables.
411.3.2 Automatic disconnection in case of a fault
411.3.2.1 Except as provided by 411.3.2.5 and 411.3.2.6, a protective device shall
automatically interrupt the supply to the line conductor of a circuit or equipment in the event of
a fault of negligible impedance between the line conductor and an exposed-conductive-part or
a protective conductor in the circuit or equipment within the disconnection time required in
411.3.2.2, 411.3.2.3 or 411.3.2.4.
NOTE 1 Higher values of disconnection time than those required in this subclause may be admitted in systems for
electricity distribution to the public and power generation and transmission for such systems.
NOTE 2 Lower values of disconnection time may be required for special installations or locations according to the
relevant Part 7 of IEC 60364.
NOTE 3 For IT systems, automatic disconnection is not usually required on the occurrence of a first fault (see
411.6.1). For the requirements for disconnection after the first fault see 411.6.4.
NOTE 4 In Belgium 411.3.2.3 is not applicable. The Belgian Wiring Rules (AREI-RGIE) do not specify differences
in automatic disconnection times between distribution circuits and final circuits.
NOTE 5 In Norway for an installation forming part of an IT system and supplied from a public network, automatic
disconnection at the first fault is required
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60364-4-41 IEC:2005 – 19 –
411.3.2.2 The maximum disconnection time stated in Table 41.1 shall be applied to final
circuits not exceeding 32A.
Table 41.1 – Maximum disconnection times
System 50 V < U ≤ 120 V 120 V < U ≤ 230 V 230 V < U ≤ 400 V U > 400 V
o o o o
s
s s s
a.c. d.c. a.c. d.c. a.c. d.c. a.c. d.c.
TN 0,8 Note 1 0,4 5 0,2 0,4 0,1 0,1
TT 0,3 Note 1 0,2 0,4 0,07 0,2 0,04 0,1
Where in TT systems the disconnection is achieved by an overcurrent protective device and the protective
equipotential bonding is connected with all extraneous-conductive-parts within the installation, the maximum
disconnection times applicable to TN systems may be used.
U is the nominal a.c. or d.c. line to earth voltage.
o
NOTE 1 Disconnection may be required for reasons other than protection against electric shock.
NOTE 2 Where disconnection is provided by an RCD see Note to 411.4.4, Note 4 to 411.5.3 and Note to 411.6.4
b).
NOTE 3 In Belgium, the last column U >400 V is not applicable. Above 400 V, the Belgian safety curve as
o
given in the Belgian Wiring Rules applies.
NOTE 4 In the Netherlands the maximum disconnection time stated in Table 41.1 is applied to all circuits not
exceeding 32 A and all circuits supplying socket-outlets.
NOTE 5 In China the maximum disconnecting time stated in Table 41.1 is applied to final circuits which supply
hand-held equipment or portable equipment.
411.3.2.3 In TN systems, a disconnection time not exceeding 5 s is permitted for distribution
circuits, and for circuits not covered by 411.3.2.2.
411.3.2.4 In TT systems, a disconnection time not exceeding 1 s is permitted for distribution
circuits and for circuits not covered by 411.3.2.2.
411.3.2.5 For systems with nominal voltage U greater than 50 V a.c. or 120 V d.c.,
o
automatic disconnection in the time required by 411.3.2.2, 411.3.2.3 or 411.3.2.4 as
appropriate is not required if in the event of a fault to a protective conductor or earth, the
output voltage of the source is reduced in not more than 5 s to 50 V a.c. or 120 V d.c. or less.
In such cases consideration shall be given to disconnection as required for reasons other than
electric shock.
411.3.2.6 If automatic disconnection according to 411.3.2.1 cannot be achieved in the time
required by 411.3.2.2, 411.3.2.3, or 411.3.2.4 as appropriate, supplementary protective
equipotential bonding shall be provided in accordance with 415.2.
411.3.3 Additional protection
In a.c. systems, additional protection by means of a residual current protective device (RCD)
in accordance with 415.1 shall be provided for
– socket-outlets with a rated current not exceeding 20 A that are for use by ordinary persons
and are intended for general use; and
NOTE 1 An exemption may be made for:
− socket-outlets for use under the supervision of skilled or instructed persons, e.g., in some commercial or
industrial locations or
− a specific socket-outlet provided for connection of a particular item of equipment.
NOTE 2 In Spain and Ireland additional protection is provided for socket-outlets with a rated current up to
32 A intended for use by ordinary persons.
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60364-4-41 IEC:2005 – 21 –
NOTE 3 In Belgium, every electrical installation under the supervision of ordinary persons must be protected
by a RCD with a rated operating residual current not exceeding 300 mA; for circuits supplying bathrooms,
washing machines, dishwashers, etc, an additional protection by means of a RCD with a rated residual
operating current not exceeding 30 mA is mandatory; the above is valid for electrical installations of which the
earthing resistance is lower than 30 Ω; in case of earthing resistance higher than 30 Ω and lower than 100 Ω,
additional RCDs with a rated operating residual current not exceeding 100 mA should be provided. An earthing
resistance higher than 100 Ω is not permitted.
NOTE 4 In Norway all commercial and industrial companies are covered by regulations requiring procedures
for qualifications and training of employees. Except for areas open for the public, socket-outlets in such
locations are normally not considered to be for general use of ordinary people. Socket-outlets in dwellings and
BA2 locations are intended for general use by ordinary people.
NOTE 5 In China a 30 mA RCD is not required for the socket-outlet supplying air conditioning equipment and
erected in position not accessible to persons.
– mobile equipment with a current rating not exceeding 32 A for use outdoors.
411.4 TN system
411.4.1 In TN systems the integrity of the earthing of the installation depends on the reliable
and effective connection of the PEN or PE conductors to earth. Where the earthing is
provided from a public or other supply system, compliance with the necessary conditions
external to the installation is the responsibility of the supply network operator.
NOTE 1 Examples of conditions include:
− the PEN is connected to earth at a number of points and is installed in such a way as to minimize the risk of a
break in the PEN conductor;
− R /R ≤ 50/(U – 50)
B E 0
where
R is the earth electrode resistance, in ohms, of all earth electrodes in parallel;
B
R is the minimum contact resistance with earth, in ohms, of extraneous-conductive-parts not connected to a
E
protective conductor, through which a fault between line and earth may occur;
U is the nominal a.c. r.m.s. voltage to earth, in volts.
o
NOTE 2 In Germany compliance with condition R /R ≤ 50 / (U – 50) is compulsory for the supply network
B E o
operator.
411.4.2 The neutral point or the midpoint of the power supply system shall be earthed. If a
neutral point or midpoint is not available or not accessible, a line conductor shall be earthed.
Exposed-conductive-parts of the installation shall be connected by a protective conductor to
the main earthing terminal of the installation which shall be connected to the earthed point of
the po
...
INTERNATIONAL IEC
STANDARD 60364-4-41
Fifth edition
2005-12
GROUP SAFETY PUBLICATION
Low-voltage electrical installations –
Part 4-41:
Protection for safety –
Protection against electric shock
© IEC 2005 Copyright - all rights reserved
No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical,
including photocopying and microfilm, without permission in writing from the publisher.
International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland
Telephone: +41 22 919 02 11 Telefax: +41 22 919 03 00 E-mail: inmail@iec.ch Web: www.iec.ch
PRICE CODE
V
Commission Electrotechnique Internationale
International Electrotechnical Commission
МеждународнаяЭлектротехническаяКомиссия
For price, see current catalogue
---------------------- Page: 1 ----------------------
60364-4-41 IEC:2005 – 3 –
CONTENTS
FOREWORD.5
410 Introduction .9
410.1 Scope .11
410.2 Normative references .11
410.3 General requirements .13
411 Protective measure: automatic disconnection of supply .15
411.1 General .15
411.2 Requirements for basic protection .17
411.3 Requirements for fault protection .17
411.4 TN systems.21
411.5 TT systems.23
411.6 IT systems.25
411.7 Functional extra-low voltage (FELV) .29
412 Protective measure: double or reinforced insulation.31
412.1 General .31
412.2 Requirements for basic protection and fault protection (protection against
indirect contact).33
413 Protective measure: electrical separation .37
413.1 General .37
413.2 Requirements for basic protection .37
413.3 Requirements for fault protection .37
414 Protective measure: extra-low-voltage provided by SELV and PELV.39
414.1 General .39
414.2 Requirements for basic protection and fault protection .39
414.3 Sources for SELV and PELV.41
414.4 Requirements for SELV and PELV circuits.41
415 Additional protection.43
415.1 Additional protection: residual current protective devices (RCDs) .45
415.2 Additional protection: supplementary protective equipotential bonding.45
Annex A (normative) Provisions for basic protection (protection against direct contact) .47
Annex B (normative) Obstacles and placing out of reach .51
Annex C (normative) Protective measures for application only when the installation is
controlled or under the supervision of skilled or instructed persons.55
Annex D (informative) Correspondence between IEC 60364-4-41(2001) and the present
standard.…. .61
Bibliography.65
Figure B.1 – Zone of arm's reach .53
Table 41.1 – Maximum disconnection times .19
Table D.1 – Correspondence between IEC 60364-4-41:2001 and the present standard .61
---------------------- Page: 2 ----------------------
60364-4-41 IEC:2005 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
LOW-VOLTAGE ELECTRICAL INSTALLATIONS –
Part 4-41: Protection for safety –
Protection against electric shock
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
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8) Attention is drawn to the normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60364-4-41 has been prepared by IEC technical committee 64:
Electrical installations and protection against electric shock.
This fifth edition cancels and replaces the fourth edition, published in 2001, and constitutes a
technical revision.
The main changes with respect to the previous edition are listed below:
– adoption of IEC 61140 terminology;
– layout rationalized on basis of complete protective measures (i.e. appropriate practical
combinations of protective provision in normal service (direct contact protection) and
protective provision in case of a fault (indirect contact protection);
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60364-4-41 IEC:2005 – 7 –
– requirements of 471 and 481, which were included in the fourth edition have been
rationalized
– disconnection requirements for TT systems clarified;
– IT systems considered more fully;
– requirements in certain cases for additional protection of socket-outlets by means of a
30 mA RCD, where the protective measure is automatic disconnection of supply.
The text of this standard is based on the following documents:
FDIS Report on voting
64/1489/FDIS 64/1500/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
It has the status of a group safety publication in accordance with IEC Guide 104.
The Part 4 series comprises the following parts under the general title Low-voltage electrical
installations:
Part 4-41: Protection for safety – Protection against electric shock
Part 4-42: Protection for safety – Protection against thermal effects
Part 4-43: Protection for safety – Protection against overcurrent
Part 4-44: Protection for safety – Protection against voltage disturbances and electromagnetic
disturbances
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result 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.
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60364-4-41 IEC:2005 – 9 –
410 Introduction
This Part 4-41 of IEC 60364 deals with protection against electric shock as applied to
electrical installations. It is based on IEC 61140 which is a basic safety standard that applies
to the protection of persons and livestock. IEC 61140 is intended to give fundamental
principles and requirements that are common to electrical installations and equipment or are
necessary for their co-ordination.
The fundamental rule of protection against electric shock, according to IEC 61140, is that
hazardous-live-parts must not be accessible and accessible conductive parts must not be
hazardous live, neither under normal conditions nor under single fault conditions.
According to 4.2 of IEC 61140, protection under normal conditions is provided by basic
protective provisions and protection under single fault conditions is provided by fault
protective provisions. Alternatively, protection against electric shock is provided by an
enhanced protective provision, which provides protection under normal conditions and under
single fault conditions.
This standard has the status of a group safety publication (GSP) for protection against electric
shock.
In the fourth edition of IEC 60364 (2001):
– protection under normal conditions (now designated basic protection) was referred to as
protection against direct contact and
– protection under fault conditions (now designated fault protection) was referred to as
protection against indirect contact.
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60364-4-41 IEC:2005 – 11 –
LOW-VOLTAGE ELECTRICAL INSTALLATIONS –
Part 4-41: Protection for safety –
Protection against electric shock
410.1 Scope
Part 4-41 of IEC 60364 specifies essential requirements regarding protection against electric
shock, including basic protection (protection against direct contact) and fault protection
(protection against indirect contact) of persons and livestock. It deals also with the application
and co-ordination of these requirements in relation to external influences.
Requirements are also given for the application of additional protection in certain cases.
410.2 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 60364-5-52, Electrical installations of buildings – Part 5-52: Selection and erection of
)
1
electrical equipment – Wiring systems
IEC 60364-5-54, Electrical installations of buildings – Part 5-54: Selection and erection of
electrical equipment – Earthing arrangements, protective conductors and protective bonding
conductors
)
2
IEC 60364-6, Low-voltage electrical installations – Part 6: Verification
IEC 60439-1, Low-voltage switchgear and controlgear assemblies – Part 1: Type-tested and
partially type-tested assemblies
IEC 60449, Voltage bands for electrical installations of buildings
IEC 60614 (all parts), Conduits for electrical installations – Specification
IEC 61084 (all parts), Cable trunking and ducting systems for electrical installations
IEC 61140, Protection against electric shock – Common aspects for installation and equipment
IEC 61386 (all parts), Conduit systems for electrical installations
IEC 61558-2-6, Safety of power transformers, power supply units and similar – Part 2-6:
Particular requirements for safety isolating transformers for general use
IEC Guide 104, The preparation of safety publications and the use of basic safety publications
and group safety publications
———————
)
1
A new edition is currently under consideration.
)
2
To be published.
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60364-4-41 IEC:2005 – 13 –
410.3 General requirements
410.3.1 In this standard the following specification of voltages is intended unless otherwise
stated:
– a.c. voltages are r.m.s.;
– d.c. voltages are ripple-free.
Ripple-free is conventionally defined as an r.m.s. ripple voltage of not more than 10 % of the
d.c. component.
410.3.2 A protective measure shall consist of
– an appropriate combination of a provision for basic protection and an independent
provision for fault protection, or
– an enhanced protective provision which provides both basic protection and fault
protection.
Additional protection is specified as part of a protective measure under certain conditions of
external influences and in certain special locations (see the corresponding Part 7 of
IEC 60364).
NOTE 1 For special applications, protective measures which do not follow this concept are permitted (see 410.3.5
and 410.3.6).
NOTE 2 An example of an enhanced protective measure is reinforced insulation.
410.3.3 In each part of an installation one or more protective measures shall be applied,
taking account of the conditions of external influence.
The following protective measures generally are permitted:
– automatic disconnection of supply (Clause 411),
– double or reinforced insulation (Clause 412),
– electrical separation for the supply of one item of current-using equipment (Clause 413),
– extra-low-voltage (SELV and PELV) (Clause 414).
The protective measures applied in the installation shall be considered in the selection and
erection of equipment.
For particular installations see 410.3.4 to 410.3.9.
NOTE In electrical installations the most commonly used protective measure is automatic disconnection of supply.
410.3.4 For special installations or locations, the particular protective measures in the
corresponding Part 7 of IEC 60364 shall be applied.
410.3.5 The protective measures, specified in Annex B, i.e. the use of obstacles and placing
out of reach, shall only be used in installations accessible to
– skilled or instructed persons, or
– persons under the supervision of skilled or instructed persons.
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60364-4-41 IEC:2005 – 15 –
410.3.6 The protective measures, specified in Annex C, i.e.
– non-conducting location,
– earth-free local equipotential bonding,
– electrical separation for the supply of more than one item of current-using equipment,
may be applied only when the installation is under the supervision of skilled or instructed
persons so that unauthorized changes cannot be made.
410.3.7 If certain conditions of a protective measure cannot be met, supplementary
provisions shall be applied so that the protective provisions together achieve the same degree
of safety.
NOTE An example of the application of this rule is given in 411.7.
410.3.8 Different protective measures applied to the same installation or part of an
installation or within equipment shall have no influence on each other such that failure of one
protective measure could impair the other protective measures.
410.3.9 The provision for fault protection (protection against indirect contact) may be omitted
for the following equipment:
– metal supports of overhead line insulators which are attached to the building and are
placed out of arm’s reach;
– steel reinforced concrete poles of overhead lines in which the steel reinforcement is not
accessible;
– exposed-conductive-parts which, owing to their reduced dimensions (approximately
50 mm x 50 mm) or their disposition cannot be gripped or come into significant contact
with a part of the human body and provided that connection with a protective conductor
could only be made with difficulty or would be unreliable.
NOTE 1 This exemption applies, for example, to bolts, rivets, nameplates and cable clips.
NOTE 2 In the USA, all exposed-conductive-parts are bonded to the protective conductor.
– metal tubes or other metal enclosures protecting equipment in accordance with
Clause 412.
411 Protective measure: automatic disconnection of supply
411.1 General
Automatic disconnection of supply is a protective measure in which
– basic protection is provided by basic insulation of live parts or by barriers or enclosures, in
accordance with Annex A, and
– fault protection is provided by protective equipotential bonding and automatic
disconnection in case of a fault in accordance with 411.3 to 411.6.
NOTE 1 Where this protective measure is applied, Class II equipment may also be used.
Where specified, additional protection is provided by a residual current protective device
(RCD) with rated residual operating current not exceeding 30 mA in accordance with 415.1.
NOTE 2 Residual current monitors (RCMs) are not protective devices but they may be used to monitor residual
currents in electrical installations. RCMs produce an audible or audible and visual signal when a preselected value
of residual current is exceeded
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60364-4-41 IEC:2005 – 17 –
411.2 Requirements for basic protection
All electrical equipment shall comply with one of the provisions for basic protection (protection
against direct contact) described in Annex A or, where appropriate, Annex B.
411.3 Requirements for fault protection
411.3.1 Protective earthing and protective equipotential bonding
411.3.1.1 Protective earthing
Exposed-conductive-parts shall be connected to a protective conductor under the specific
conditions for each type of system earthing as specified in 411.4 to 411.6.
Simultaneously accessible exposed-conductive-parts shall be connected to the same earthing
system individually, in groups or collectively.
Conductors for protective earthing shall comply with IEC 60364-5-54.
Each circuit shall have available a protective conductor connected to the relevant earthing
terminal.
411.3.1.2 Protective equipotential bonding
In each building the earthing conductor, the main earthing terminal and the following
conductive parts shall be connected to the protective equipotential bonding:
– metallic pipes supplying services into the building, e.g. gas, water;
– structural extraneous-conductive-parts if accessible in normal use, metallic central heating
and air-conditioning systems.
– metallic reinforcements of constructional reinforced concrete, if reasonably practicable.
Where such conductive parts originate outside the building, they shall be bonded as close as
practicable to their point of entry within the building.
Conductors for protective equipotential bonding shall comply with IEC 60364-5-54.
Any metallic sheath of telecommunication cables shall be connected to the protective
equipotential bonding, taking account of the requirements of the owners or operators of these
cables.
411.3.2 Automatic disconnection in case of a fault
411.3.2.1 Except as provided by 411.3.2.5 and 411.3.2.6, a protective device shall
automatically interrupt the supply to the line conductor of a circuit or equipment in the event of
a fault of negligible impedance between the line conductor and an exposed-conductive-part or
a protective conductor in the circuit or equipment within the disconnection time required in
411.3.2.2, 411.3.2.3 or 411.3.2.4.
NOTE 1 Higher values of disconnection time than those required in this subclause may be admitted in systems for
electricity distribution to the public and power generation and transmission for such systems.
NOTE 2 Lower values of disconnection time may be required for special installations or locations according to the
relevant Part 7 of IEC 60364.
NOTE 3 For IT systems, automatic disconnection is not usually required on the occurrence of a first fault (see
411.6.1). For the requirements for disconnection after the first fault see 411.6.4.
NOTE 4 In Belgium 411.3.2.3 is not applicable. The Belgian Wiring Rules (AREI-RGIE) do not specify differences
in automatic disconnection times between distribution circuits and final circuits.
NOTE 5 In Norway for an installation forming part of an IT system and supplied from a public network, automatic
disconnection at the first fault is required
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60364-4-41 IEC:2005 – 19 –
411.3.2.2 The maximum disconnection time stated in Table 41.1 shall be applied to final
circuits not exceeding 32A.
Table 41.1 – Maximum disconnection times
System 50 V < U ≤ 120 V 120 V < U ≤ 230 V 230 V < U ≤ 400 V U > 400 V
o o o o
s
s s s
a.c. d.c. a.c. d.c. a.c. d.c. a.c. d.c.
TN 0,8 Note 1 0,4 5 0,2 0,4 0,1 0,1
TT 0,3 Note 1 0,2 0,4 0,07 0,2 0,04 0,1
Where in TT systems the disconnection is achieved by an overcurrent protective device and the protective
equipotential bonding is connected with all extraneous-conductive-parts within the installation, the maximum
disconnection times applicable to TN systems may be used.
U is the nominal a.c. or d.c. line to earth voltage.
o
NOTE 1 Disconnection may be required for reasons other than protection against electric shock.
NOTE 2 Where disconnection is provided by an RCD see Note to 411.4.4, Note 4 to 411.5.3 and Note to 411.6.4
b).
NOTE 3 In Belgium, the last column U >400 V is not applicable. Above 400 V, the Belgian safety curve as
o
given in the Belgian Wiring Rules applies.
NOTE 4 In the Netherlands the maximum disconnection time stated in Table 41.1 is applied to all circuits not
exceeding 32 A and all circuits supplying socket-outlets.
NOTE 5 In China the maximum disconnecting time stated in Table 41.1 is applied to final circuits which supply
hand-held equipment or portable equipment.
411.3.2.3 In TN systems, a disconnection time not exceeding 5 s is permitted for distribution
circuits, and for circuits not covered by 411.3.2.2.
411.3.2.4 In TT systems, a disconnection time not exceeding 1 s is permitted for distribution
circuits and for circuits not covered by 411.3.2.2.
411.3.2.5 For systems with nominal voltage U greater than 50 V a.c. or 120 V d.c.,
o
automatic disconnection in the time required by 411.3.2.2, 411.3.2.3 or 411.3.2.4 as
appropriate is not required if in the event of a fault to a protective conductor or earth, the
output voltage of the source is reduced in not more than 5 s to 50 V a.c. or 120 V d.c. or less.
In such cases consideration shall be given to disconnection as required for reasons other than
electric shock.
411.3.2.6 If automatic disconnection according to 411.3.2.1 cannot be achieved in the time
required by 411.3.2.2, 411.3.2.3, or 411.3.2.4 as appropriate, supplementary protective
equipotential bonding shall be provided in accordance with 415.2.
411.3.3 Additional protection
In a.c. systems, additional protection by means of a residual current protective device (RCD)
in accordance with 415.1 shall be provided for
– socket-outlets with a rated current not exceeding 20 A that are for use by ordinary persons
and are intended for general use; and
NOTE 1 An exemption may be made for:
− socket-outlets for use under the supervision of skilled or instructed persons, e.g., in some commercial or
industrial locations or
− a specific socket-outlet provided for connection of a particular item of equipment.
NOTE 2 In Spain and Ireland additional protection is provided for socket-outlets with a rated current up to
32 A intended for use by ordinary persons.
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60364-4-41 IEC:2005 – 21 –
NOTE 3 In Belgium, every electrical installation under the supervision of ordinary persons must be protected
by a RCD with a rated operating residual current not exceeding 300 mA; for circuits supplying bathrooms,
washing machines, dishwashers, etc, an additional protection by means of a RCD with a rated residual
operating current not exceeding 30 mA is mandatory; the above is valid for electrical installations of which the
earthing resistance is lower than 30 Ω; in case of earthing resistance higher than 30 Ω and lower than 100 Ω,
additional RCDs with a rated operating residual current not exceeding 100 mA should be provided. An earthing
resistance higher than 100 Ω is not permitted.
NOTE 4 In Norway all commercial and industrial companies are covered by regulations requiring procedures
for qualifications and training of employees. Except for areas open for the public, socket-outlets in such
locations are normally not considered to be for general use of ordinary people. Socket-outlets in dwellings and
BA2 locations are intended for general use by ordinary people.
NOTE 5 In China a 30 mA RCD is not required for the socket-outlet supplying air conditioning equipment and
erected in position not accessible to persons.
– mobile equipment with a current rating not exceeding 32 A for use outdoors.
411.4 TN system
411.4.1 In TN systems the integrity of the earthing of the installation depends on the reliable
and effective connection of the PEN or PE conductors to earth. Where the earthing is
provided from a public or other supply system, compliance with the necessary conditions
external to the installation is the responsibility of the supply network operator.
NOTE 1 Examples of conditions include:
− the PEN is connected to earth at a number of points and is installed in such a way as to minimize the risk of a
break in the PEN conductor;
− R /R ≤ 50/(U – 50)
B E 0
where
R is the earth electrode resistance, in ohms, of all earth electrodes in parallel;
B
R is the minimum contact resistance with earth, in ohms, of extraneous-conductive-parts not connected to a
E
protective conductor, through which a fault between line and earth may occur;
U is the nominal a.c. r.m.s. voltage to earth, in volts.
o
NOTE 2 In Germany compliance with condition R /R ≤ 50 / (U – 50) is compulsory for the supply network
B E o
operator.
411.4.2 The neutral point or the midpoint of the power supply system shall be earthed. If a
neutral point or midpoint is not available or not accessible, a line conductor shall be earthed.
Exposed-conductive-parts of the installation shall be connected by a protective conductor to
the main earthing terminal of the installation which shall be connected to the earthed point of
the power supply system.
NOTE 1 If other effective earth connections exist, it is recommended that the protective conductors also be
connected to such points wherever possible. Earthing at additional points, distributed as evenly as possible, may
be necessary to ensure that the potentials of protective conductors remain, in case of a fault, as near as possible
to that of earth.
In large buildings such as high-rise buildings, additional earthing of protective conductors is not possible for
practical reasons. In such buildings protective-equipotential-bonding between protective conductors and
extraneous-conductive-parts has, however, a similar function.
NOTE 2 It i
...
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