IEC 61439-4:2023

IEC 61439-4 ®
Edition 2.0 2023-10
EXTENDED VERSION
INTERNATIONAL
STANDARD
colour
inside
This extended version of IEC 61439-4:2023 includes the content of the references made to
IEC 61439-1:2020
Low-voltage switchgear and controlgear assemblies –
Part 4: Particular requirements for assemblies for construction sites (ACS)

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IEC 61439-4 ®
Edition 2.0 2023-10
EXTENDED VERSION
INTERNATIONAL
STANDARD
colour
inside
This extended version of IEC 61439-4:2023 includes the content of the references made to
IEC 61439-1:2020
Low-voltage switchgear and controlgear assemblies –
Part 4: Particular requirements for assemblies for construction sites (ACS)
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.130.20 ISBN 978-2-8322-7709-6

– 2 – IEC 61439-4:2023 EXV © IEC 2023
CONTENTS
FOREWORD . 8
INTRODUCTION . 11
1 Scope . 12
2 Normative references . 12
3 Terms and definitions . 15
3.1 General terms . 16
3.2 Constructional units of assemblies . 18
3.3 External design of assemblies . 19
3.4 Structural parts of assemblies . 20
3.5 Conditions of installation of assemblies . 22
3.6 Insulation characteristics . 22
3.7 Protection against electric shock . 25
3.8 Characteristics . 29
3.9 Verification . 33
3.10 Manufacturer . 33
3.101 Function of the ACS . 34
4 Symbols and abbreviations . 34
5 Interface characteristics . 35
5.1 General . 35
5.2 Voltage ratings . 35
5.2.1 Rated voltage (U ) (of the assembly) . 35
n
5.2.2 Rated operational voltage (U ) (of a circuit of an assembly) . 36
e
5.2.3 Rated insulation voltage (U ) (of a circuit of an assembly) . 36
i
5.2.4 Rated impulse withstand voltage (U ) (of the assembly) . 36
imp
5.3 Current ratings . 36
5.3.1 Rated current of an ACS (I ) . 36
nA
5.3.2 Rated current of a main outgoing circuit (I ) . 36
nc
5.3.3 Group rated current of a main circuit (I ) . 37
ng
5.3.4 Rated peak withstand current (I ) . 37
pk
5.3.5 Rated short-time withstand current (I ) (of a main circuit of an
cw
assembly) . 37
5.3.6 Rated conditional short-circuit current (I ) (of an assembly or a circuit
cc
of an assembly) . 38
5.4 Rated diversity factor (RDF) . 38
5.5 Rated frequency (f ) . 38
n
5.6 Other characteristics . 38
6 Information . 39
6.1 ACS designation marking . 39
6.2 Documentation . 39
6.2.1 Information relating to the ACS . 39
6.2.2 Instructions for handling, installation, operation and maintenance . 40
6.3 Device and/or component identification . 41
7 Service conditions . 41
7.1 Normal service conditions . 41
7.1.1 Climatic conditions . 41
7.1.2 Pollution degree . 41

7.2 Special service conditions . 42
7.3 Conditions during transport, storage and installation . 42
8 Constructional requirements . 42
8.1 Strength of materials and parts . 42
8.1.1 General . 42
8.1.2 Protection against corrosion . 43
8.1.3 Properties of insulating materials . 43
8.1.4 Resistance to ultra-violet (UV) radiation . 44
8.1.5 Mechanical strength . 44
8.1.6 Lifting provision . 44
8.2 Degree of protection provided by an assembly enclosure . 44
8.2.1 Protection against mechanical impact (IK code) . 44
8.2.2 Protection against contact with live parts, ingress of solid foreign bodies
and water (IP code) . 45
8.2.3 Assembly with removable parts. 45
8.3 Clearances and creepage distances. 45
8.3.1 General . 45
8.3.2 Clearances . 46
8.3.3 Creepage distances . 46
8.4 Protection against electric shock . 47
8.4.1 General . 47
8.4.2 Basic protection . 47
8.4.3 Fault protection . 48
8.4.4 Additional requirements for class II assemblies . 51
8.4.5 Limitation of steady-state touch currents and charge . 51
8.4.6 Operating and servicing conditions . 52
8.5 Incorporation of switching devices and components . 52
8.5.1 Fixed parts . 52
8.5.2 Removable parts . 52
8.5.3 Selection of switching devices and components . 52
8.5.4 Installation of switching devices and components . 53
8.5.5 Accessibility . 53
8.5.6 Barriers . 53
8.5.7 Direction of operation and indication of switching positions . 54
8.5.8 Indicator lights and push-buttons . 54
8.5.9 Power factor correction banks . 54
8.5.101 Accessible parts of ACS . 54
8.6 Internal electrical circuits and connections . 54
8.6.1 Main circuits . 54
8.6.2 Auxiliary circuits . 55
8.6.3 Bare and insulated conductors . 55
8.6.4 Selection and installation of non-protected live conductors to reduce the
possibility of short-circuits . 56
8.6.5 Identification of the conductors of main and auxiliary circuits . 56
8.6.6 Identification of the protective conductor (PE, PEL, PEM, PEN) and of
the neutral conductor (N) and the mid-point conductor (M) of the main
circuits . 56
8.6.7 Conductors in AC circuits passing through ferromagnetic enclosures or
plates . 57
8.7 Cooling . 57

– 4 – IEC 61439-4:2023 EXV © IEC 2023
8.8 Terminals for external cables . 57
8.101 Supports and securing devices of ACS . 58
8.102 Cable outlet . 59
9 Performance requirements . 59
9.1 Dielectric properties . 59
9.1.1 General . 59
9.1.2 Power-frequency withstand voltage . 59
9.1.3 Impulse withstand voltage . 59
9.1.4 Protection of surge protective devices . 60
9.2 Temperature-rise limits . 60
9.2.1 General . 60
9.2.2 Adjustment of rated currents for alternative ambient air temperatures . 60
9.3 Short-circuit protection and short-circuit withstand strength . 61
9.3.1 General . 61
9.3.2 Information concerning short-circuit withstand strength . 61
9.3.3 Relationship between peak current and short-time current . 61
9.3.4 Coordination of protective devices . 62
9.4 Electromagnetic compatibility (EMC) . 62
10 Design verification . 62
10.1 General . 62
10.2 Strength of materials and parts . 64
10.2.1 General . 64
10.2.2 Resistance to corrosion . 64
10.2.3 Properties of insulating materials . 66
10.2.4 Resistance to ultraviolet (UV) radiation . 67
10.2.5 Lifting . 68
10.2.6 Verification of mechanical strength . 69
10.2.7 Marking . 70
10.2.8 Mechanical operation . 71
10.3 Degree of protection of assemblies (IP Code) . 71
10.4 Clearances and creepage distances. 72
10.5 Protection against electric shock and integrity of protective circuits . 72
10.5.1 General . 72
10.5.2 Effective earth continuity between the exposed-conductive-parts of the
class I assembly and the protective circuit . 72
10.5.3 Short-circuit withstand strength of the protective circuit . 73
10.6 Incorporation of switching devices and components . 73
10.6.1 General . 73
10.6.2 Electromagnetic compatibility . 74
10.7 Internal electrical circuits and connections . 74
10.8 Terminals for external conductors . 74
10.9 Dielectric properties . 74
10.9.1 General . 74
10.9.2 Power-frequency withstand voltage . 74
10.9.3 Impulse withstand voltage . 75
10.9.4 Testing of enclosures made of insulating material . 77
10.9.5 External door or cover mounted operating handles of insulating material . 77
10.9.6 Testing of conductors and hazardous live parts covered by insulating
material to provide protection against electric shock . 78

10.10 Temperature-rise . 78
10.10.1 General . 78
10.10.2 Verification by testing . 78
10.10.3 Verification by comparison . 85
10.10.4 Verification assessment . 87
10.11 Short-circuit withstand strength . 87
10.11.1 General . 87
10.11.2 Circuits of assemblies which are exempted from the verification of the
short-circuit withstand strength . 87
10.11.3 Verification by comparison with a reference design – Using a checklist . 88
10.11.4 Verification by comparison with a reference design(s) – Using

calculation . 88
10.11.5 Verification by test . 88
10.12 Electromagnetic compatibility (EMC) . 94
11 Routine verification . 94
11.1 General . 94
11.2 Degree of protection against contact with hazardous live parts, ingress of
solid foreign bodies and water of enclosures . 95
11.3 Clearances and creepage distances. 95
11.4 Protection against electric shock and integrity of protective circuits . 95
11.5 Incorporation of built-in components . 96
11.6 Internal electrical circuits and connections . 96
11.7 Terminals for external conductors . 96
11.8 Mechanical operation . 96
11.9 Dielectric properties . 96
11.10 Wiring, operational performance and function . 96
101 Particular features of ACS . 97
101.1 General requirements and functions. 97
101.2 Incoming unit . 97
101.3 Metering unit . 97
101.4 Transformer unit . 97
101.4.1 General . 97
101.4.2 LV/ELV unit . 97
101.4.3 LV/LV units . 98
101.5 Outgoing units . 98
Annex A (normative) Minimum and maximum cross-section of copper cables suitable
for connection to terminals for external cables (see 8.8) . 109
Annex B (normative) Method of calculating the cross-sectional area of protective
conductors with regard to thermal stresses due to currents of short duration . 110
Annex C (informative) User information template . 111
Annex D (informative) Design verification . 115
Annex E (informative) Rated diversity factor . 116
E.1 General . 116
E.2 Rated diversity factor for outgoing circuits within an assembly . 116
E.2.1 General . 116
E.2.2 Example of an assembly with an RDF of 0,68 . 119
E.2.3 Example of an assembly with RDF declared for each section . 120
Annex F (normative) Measurement of clearances and creepage distances . 121
F.1 Basic principles . 121

– 6 – IEC 61439-4:2023 EXV © IEC 2023
F.2 Use of ribs . 121
Annex G (normative) Correlation between the nominal voltage of the supply system
and the rated impulse withstand voltage of the equipment . 126
Annex H (informative) Operating current and power loss of copper cables . 128
Annex I (informative) Thermal equivalent of an intermittent current . 130
Annex J (normative) Electromagnetic compatibility (EMC). 131
J.1 General . 131
Annex K (normative) Operating current and power loss of bare copper bars . 138
Annex L (informative) Guidance on verification of temperature-rise . 141
L.1 General . 141
L.1.1 Principles . 141
L.1.2 Current ratings of assemblies . 141
L.2 Temperature-rise limits . 142
L.3 Test . 143
L.3.1 General . 143
L.3.2 Method a) – Verification of the complete assembly (10.10.2.3.5) . 143
L.3.3 Method b) – Verification considering individual functional units

separately and the complete assembly (10.10.2.3.6) . 143
L.3.4 Method c) – Verification considering individual functional units and the
main and distribution busbars separately as well as the complete
assembly (10.10.2.3.7) . 144
L.4 Verification assessment . 144
L.5 Verification by comparison with a reference design . 144
Annex M (normative) Verification of the short-circuit withstand strength of busbar
structures by comparison with a reference design by calculation . 145
Annex N (informative) List of notes concerning certain countries . 146
Bibliography . 147

Figure 101 – Impact test using striking element . 70
Figure E.1 – Typical assembly . 117
Figure E.2 – Example 1: Table E.1 – Functional unit loading for an assembly with a
rated diversity factor of 0,68 . 119
Figure E.3 – Example 2: Table E.1 – Functional unit loading for an assembly with a

rated diversity factor of 0,6 in Section B and 0,68 in Section C . 120
Figure F.1 – Measurement of clearance and creepage distances . 125
Figure I.1 – Example of average heating effect calculation . 130
Figure J.1 – Examples of ports . 131
Figure L.1 – Not applicable . 144

Table 1 – Minimum clearances in air (8.3.2) . 99
Table 2 – Minimum creepage distances (8.3.3) . 100
Table 3 – Cross-sectional area of a copper protective conductor (8.4.3.2.2) . 101
Table 4 – Conductor selection and installation requirements (8.6.4) . 101
Table 5 – Minimum terminal capacity for copper protective conductors (PE) (8.8) . 101
Table 6 – Temperature-rise limits (9.2) . 102
a
Table 7 – Values for the factor n (9.3.3) . 103
Table 8 – Power-frequency withstand voltage for main circuits (10.9.2) . 103

Table 9 – Power-frequency withstand voltage for auxiliary circuits (10.9.2) . 103
Table 10 – Impulse withstand test voltages (10.9.3) . 103
Table 11 – Copper test conductors for rated currents up to 400 A inclusive
(10.10.2.3.2) . 104
Table 12 – Copper test conductors for rated currents from 400 A to 7 000 A

(10.10.2.3.2) . 105
Table 13 – Short-circuit verification by comparison with reference designs: checklist
(10.5.3.3, 10.11.3 and 10.11.4) . 106
Table 14 – Relationship between prospective fault current and diameter of copper wire . 107
Table 15 – Climatic conditions . 107
Table 101 – Values of assumed loading . 108
Table A.1 – Cross-section of copper cables suitable for connection to terminals for
external cables . 109
Table B.1 – Values of k for insulated protective conductors not incorporated in cables
or bare protective conductors in contact with cable covering . 110
Table C.1 – Items subject to agreement between the assembly manufacturer
and the user . 111
Table D.1 – List of design verifications to be performed . 115
Table E.1 – Examples of loading for an assembly . 118
Table F.1 – Minimum width of grooves . 121
Table G.1 – Correspondence between the nominal voltage of the supply system and
the equipment rated impulse withstand voltage . 127
Table H.1 – Operating current and power loss of single-core copper cables with a
permissible conductor temperature of 70 °C (ambient temperature inside the assembly:
55 °C) . 128
Table H.2 – Reduction factor k for cables with a permissible conductor temperature
of 70 °C (extract from IEC 60364-5-52:2009, Table B.52.14). 129
Table J.1 – Tests for EMC immunity for environment A (see J.10.12.2) . 135
Table J.2 – Tests for EMC immunity for environment B (see J.10.12.2) . 136
Table J.3 – Acceptance criteria when electromagnetic disturbances are present . 137
Table K.1 – Operating current and power loss of bare copper bars with rectangular
cross-section, run horizontally and arranged with their largest face vertical, frequency
50 Hz to 60 Hz (ambient air temperature inside the assembly: 55 °C, temperature of
the conductor 70 °C) . 138
Table K.2 – Factor k for different temperatures of the air inside the assembly and/or
for the conductors . 139

– 8 – IEC 61439-4:2023 EXV © IEC 2023
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR ASSEMBLIES –

Part 1: General rules
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
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2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
This extended version (EXV) of the official IEC Standard provides the user with the
comprehensive content of the Standard.
to IEC 61439-1:2020.
The specific content of IEC 61439-4:2023 is displayed on a blue background.

IEC 61439-4 has been prepared by subcommittee 121B: Low-voltage switchgear and
controlgear assemblies, of IEC technical committee 121: Switchgear and controlgear and their
assemblies for low voltage. It is an International Standard.
This second edition of IEC 61439-4 cancels and replaces the first edition published in 2012.
This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) alignment with IEC 61439-1:2020 regarding the structure and technical content, as
applicable.
The text of this document is based on the following documents:
Draft Report on voting
121B/183/FDIS 121B/188/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement,
available at www.iec.ch/members_experts/refdocs. The main document types developed by
IEC are described in greater detail at www.iec.ch/publications.
This document is to be read in conjunction with IEC 61439-1:2020. The provisions of the
general rules dealt with in IEC 61439-1:2020 are only applicable to this document insofar as
they are specifically cited. When this document states “addition”, “modification” or
“replacement”, the relevant text in IEC 61439-1:2020 is to be adapted accordingly.
Subclauses that are numbered with a 101 (102, 103, etc.) suffix are additional to the same
subclause in IEC 61439-1:2020.
Tables and figures in this document that are new are numbered starting with 101.
New annexes in this document are lettered AA, BB, etc.
In this document, terms written in small capitals are defined in Clause 3.
The reader’s attention is drawn to the fact that Annex N lists all of the “in-some-country”
clauses on differing practices of a less permanent nature relating to the subject of this
document.
A list of all parts of the IEC 61439 series, under the general title Low-voltage switchgear and
controlgear assemblies, can be found on the IEC website.

– 10 – IEC 61439-4:2023 EXV © IEC 2023
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be:
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The "colour inside" logo on the cover page of this document indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
INTRODUCTION
The purpose of this document is to harmonize as far as practicable all rules and requirements
of a general nature applicable to low-voltage switchgear and controlgear assemblies, in order
to obtain uniformity of requirements and verification for assemblies and to avoid the need for
verification in other standards. All those requirements for the various assembly standards
which can be considered as general have therefore been gathered in this document together
with specific subjects of wide interest and application, e.g. temperature-rise, dielectric
properties, etc.
For each type of low-voltage switchgear and controlgear assembly, only two main standards
are necessary to determine all requirements and the corresponding methods of verification:
– the basic standard, (this document) referred to as “IEC 61439-1” in the specific standards,
covering the various types of low-voltage switchgear and controlgear assemblies;
– the specific assembly standard hereinafter also referred to as the relevant assembly
standard.
For a general rule to apply to a specific assembly standard, it should be explicitly referred to
by quoting this document followed by the relevant clause or subclause number e.g.
“IEC 61439-1:2020, 9.1.3”.
A specific assembly standard may not require, and hence need not call up, a general rule
where it is not applicable, or it can add requirements if the general rule is deemed inadequate
in the particular case, but it may not deviate from it unless there is substantial technical
justification detailed in the specific assembly standard.
Where, in this document, a cross-reference is made to another clause, the reference is to be
taken to apply to that clause as amended by the specific assembly standard, where applicable.
Requirements in this document that are subject to agreement between the assembly
manufacturer and the user are summarized in Annex C (informative). This schedule also
facilitates the supply of information on basic conditions and additional user specifications to
enable proper design, application and utilization of the assembly.
For the IEC 61439 series, the following parts are published:
a) IEC 61439-1: General rules
b) IEC 61439-2: Power switchgear and controlgear assemblies (PSC-assemblies)
c) IEC 61439-3: Distribution boards intended to be operated by ordinary persons (DBO)
d) IEC 61439-4: Particular requirements for assemblies for construction sites (ACS)
e) IEC 61439-5: Assemblies for power distribution in public networks
f) IEC 61439-6: Busbar trunking systems (busways)
g) IEC 61439-7: Assemblies for specific applications such as marinas, camping sites, market
squares, electric vehicle charging stations
h) IEC TR 61439-0: Guidance to specifying assemblies.
This list is not exhaustive; additional parts can be developed as the need arises.

___________
IEC 61439-2 includes requirements for assemblies for use in photovoltaic installations.

– 12 – IEC 61439-4:2023 EXV © IEC
...

IEC 61439-4 ®
Edition 2.0 2023-10
EXTENDED VERSION
INTERNATIONAL
STANDARD
colour
inside
This extended version of IEC 61439-4:2023 includes the content of the references made to
IEC 61439-1:2020
Low-voltage switchgear and controlgear assemblies –
Part 4: Particular requirements for assemblies for construction sites (ACS)

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.

IEC Secretariat Tel.: +41 22 919 02 11
3, rue de Varembé info@iec.ch
CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigendum or an amendment might have been published.

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The advanced search enables to find IEC publications by a Discover our powerful search engine and read freely all the
variety of criteria (reference number, text, technical publications previews. With a subscription you will always have
committee, …). It also gives information on projects, replaced access to up to date content tailored to your needs.
and withdrawn publications.
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IEC Just Published - webstore.iec.ch/justpublished
The world's leading online dictionary on electrotechnology,
Stay up to date on all new IEC publications. Just Published
containing more than 22 300 terminological entries in English
details all new publications released. Available online and once
and French, with equivalent terms in 19 additional languages.
a month by email.
Also known as the International Electrotechnical Vocabulary

(IEV) online.
IEC Customer Service Centre - webstore.iec.ch/csc

If you wish to give us your feedback on this publication or need
further assistance, please contact the Customer Service
Centre: sales@iec.ch.
IEC 61439-4 ®
Edition 2.0 2023-10
EXTENDED VERSION
INTERNATIONAL
STANDARD
colour
inside
This extended version of IEC 61439-4:2023 includes the content of the references made to
IEC 61439-1:2020
Low-voltage switchgear and controlgear assemblies –
Part 4: Particular requirements for assemblies for construction sites (ACS)
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.130.20 ISBN 978-2-8322-7709-6

– 2 – IEC 61439-4:2023 EXV © IEC 2023
CONTENTS
FOREWORD . 8
INTRODUCTION . 11
1 Scope . 12
2 Normative references . 12
3 Terms and definitions . 15
3.1 General terms . 16
3.2 Constructional units of assemblies . 18
3.3 External design of assemblies . 19
3.4 Structural parts of assemblies . 20
3.5 Conditions of installation of assemblies . 22
3.6 Insulation characteristics . 22
3.7 Protection against electric shock . 25
3.8 Characteristics . 29
3.9 Verification . 33
3.10 Manufacturer . 33
3.101 Function of the ACS . 34
4 Symbols and abbreviations . 34
5 Interface characteristics . 35
5.1 General . 35
5.2 Voltage ratings . 35
5.2.1 Rated voltage (U ) (of the assembly) . 35
n
5.2.2 Rated operational voltage (U ) (of a circuit of an assembly) . 36
e
5.2.3 Rated insulation voltage (U ) (of a circuit of an assembly) . 36
i
5.2.4 Rated impulse withstand voltage (U ) (of the assembly) . 36
imp
5.3 Current ratings . 36
5.3.1 Rated current of an ACS (I ) . 36
nA
5.3.2 Rated current of a main outgoing circuit (I ) . 36
nc
5.3.3 Group rated current of a main circuit (I ) . 37
ng
5.3.4 Rated peak withstand current (I ) . 37
pk
5.3.5 Rated short-time withstand current (I ) (of a main circuit of an
cw
assembly) . 37
5.3.6 Rated conditional short-circuit current (I ) (of an assembly or a circuit
cc
of an assembly) . 38
5.4 Rated diversity factor (RDF) . 38
5.5 Rated frequency (f ) . 38
n
5.6 Other characteristics . 38
6 Information . 39
6.1 ACS designation marking . 39
6.2 Documentation . 39
6.2.1 Information relating to the ACS . 39
6.2.2 Instructions for handling, installation, operation and maintenance . 40
6.3 Device and/or component identification . 41
7 Service conditions . 41
7.1 Normal service conditions . 41
7.1.1 Climatic conditions . 41
7.1.2 Pollution degree . 41

7.2 Special service conditions . 42
7.3 Conditions during transport, storage and installation . 42
8 Constructional requirements . 42
8.1 Strength of materials and parts . 42
8.1.1 General . 42
8.1.2 Protection against corrosion . 43
8.1.3 Properties of insulating materials . 43
8.1.4 Resistance to ultra-violet (UV) radiation . 44
8.1.5 Mechanical strength . 44
8.1.6 Lifting provision . 44
8.2 Degree of protection provided by an assembly enclosure . 44
8.2.1 Protection against mechanical impact (IK code) . 44
8.2.2 Protection against contact with live parts, ingress of solid foreign bodies
and water (IP code) . 45
8.2.3 Assembly with removable parts. 45
8.3 Clearances and creepage distances. 45
8.3.1 General . 45
8.3.2 Clearances . 46
8.3.3 Creepage distances . 46
8.4 Protection against electric shock . 47
8.4.1 General . 47
8.4.2 Basic protection . 47
8.4.3 Fault protection . 48
8.4.4 Additional requirements for class II assemblies . 51
8.4.5 Limitation of steady-state touch currents and charge . 51
8.4.6 Operating and servicing conditions . 52
8.5 Incorporation of switching devices and components . 52
8.5.1 Fixed parts . 52
8.5.2 Removable parts . 52
8.5.3 Selection of switching devices and components . 52
8.5.4 Installation of switching devices and components . 53
8.5.5 Accessibility . 53
8.5.6 Barriers . 53
8.5.7 Direction of operation and indication of switching positions . 54
8.5.8 Indicator lights and push-buttons . 54
8.5.9 Power factor correction banks . 54
8.5.101 Accessible parts of ACS . 54
8.6 Internal electrical circuits and connections . 54
8.6.1 Main circuits . 54
8.6.2 Auxiliary circuits . 55
8.6.3 Bare and insulated conductors . 55
8.6.4 Selection and installation of non-protected live conductors to reduce the
possibility of short-circuits . 56
8.6.5 Identification of the conductors of main and auxiliary circuits . 56
8.6.6 Identification of the protective conductor (PE, PEL, PEM, PEN) and of
the neutral conductor (N) and the mid-point conductor (M) of the main
circuits . 56
8.6.7 Conductors in AC circuits passing through ferromagnetic enclosures or
plates . 57
8.7 Cooling . 57

– 4 – IEC 61439-4:2023 EXV © IEC 2023
8.8 Terminals for external cables . 57
8.101 Supports and securing devices of ACS . 58
8.102 Cable outlet . 59
9 Performance requirements . 59
9.1 Dielectric properties . 59
9.1.1 General . 59
9.1.2 Power-frequency withstand voltage . 59
9.1.3 Impulse withstand voltage . 59
9.1.4 Protection of surge protective devices . 60
9.2 Temperature-rise limits . 60
9.2.1 General . 60
9.2.2 Adjustment of rated currents for alternative ambient air temperatures . 60
9.3 Short-circuit protection and short-circuit withstand strength . 61
9.3.1 General . 61
9.3.2 Information concerning short-circuit withstand strength . 61
9.3.3 Relationship between peak current and short-time current . 61
9.3.4 Coordination of protective devices . 62
9.4 Electromagnetic compatibility (EMC) . 62
10 Design verification . 62
10.1 General . 62
10.2 Strength of materials and parts . 64
10.2.1 General . 64
10.2.2 Resistance to corrosion . 64
10.2.3 Properties of insulating materials . 66
10.2.4 Resistance to ultraviolet (UV) radiation . 67
10.2.5 Lifting . 68
10.2.6 Verification of mechanical strength . 69
10.2.7 Marking . 70
10.2.8 Mechanical operation . 71
10.3 Degree of protection of assemblies (IP Code) . 71
10.4 Clearances and creepage distances. 72
10.5 Protection against electric shock and integrity of protective circuits . 72
10.5.1 General . 72
10.5.2 Effective earth continuity between the exposed-conductive-parts of the
class I assembly and the protective circuit . 72
10.5.3 Short-circuit withstand strength of the protective circuit . 73
10.6 Incorporation of switching devices and components . 73
10.6.1 General . 73
10.6.2 Electromagnetic compatibility . 74
10.7 Internal electrical circuits and connections . 74
10.8 Terminals for external conductors . 74
10.9 Dielectric properties . 74
10.9.1 General . 74
10.9.2 Power-frequency withstand voltage . 74
10.9.3 Impulse withstand voltage . 75
10.9.4 Testing of enclosures made of insulating material . 77
10.9.5 External door or cover mounted operating handles of insulating material . 77
10.9.6 Testing of conductors and hazardous live parts covered by insulating
material to provide protection against electric shock . 78

10.10 Temperature-rise . 78
10.10.1 General . 78
10.10.2 Verification by testing . 78
10.10.3 Verification by comparison . 85
10.10.4 Verification assessment . 87
10.11 Short-circuit withstand strength . 87
10.11.1 General . 87
10.11.2 Circuits of assemblies which are exempted from the verification of the
short-circuit withstand strength . 87
10.11.3 Verification by comparison with a reference design – Using a checklist . 88
10.11.4 Verification by comparison with a reference design(s) – Using

calculation . 88
10.11.5 Verification by test . 88
10.12 Electromagnetic compatibility (EMC) . 94
11 Routine verification . 94
11.1 General . 94
11.2 Degree of protection against contact with hazardous live parts, ingress of
solid foreign bodies and water of enclosures . 95
11.3 Clearances and creepage distances. 95
11.4 Protection against electric shock and integrity of protective circuits . 95
11.5 Incorporation of built-in components . 96
11.6 Internal electrical circuits and connections . 96
11.7 Terminals for external conductors . 96
11.8 Mechanical operation . 96
11.9 Dielectric properties . 96
11.10 Wiring, operational performance and function . 96
101 Particular features of ACS . 97
101.1 General requirements and functions. 97
101.2 Incoming unit . 97
101.3 Metering unit . 97
101.4 Transformer unit . 97
101.4.1 General . 97
101.4.2 LV/ELV unit . 97
101.4.3 LV/LV units . 98
101.5 Outgoing units . 98
Annex A (normative) Minimum and maximum cross-section of copper cables suitable
for connection to terminals for external cables (see 8.8) . 109
Annex B (normative) Method of calculating the cross-sectional area of protective
conductors with regard to thermal stresses due to currents of short duration . 110
Annex C (informative) User information template . 111
Annex D (informative) Design verification . 115
Annex E (informative) Rated diversity factor . 116
E.1 General . 116
E.2 Rated diversity factor for outgoing circuits within an assembly . 116
E.2.1 General . 116
E.2.2 Example of an assembly with an RDF of 0,68 . 119
E.2.3 Example of an assembly with RDF declared for each section . 120
Annex F (normative) Measurement of clearances and creepage distances . 121
F.1 Basic principles . 121

– 6 – IEC 61439-4:2023 EXV © IEC 2023
F.2 Use of ribs . 121
Annex G (normative) Correlation between the nominal voltage of the supply system
and the rated impulse withstand voltage of the equipment . 126
Annex H (informative) Operating current and power loss of copper cables . 128
Annex I (informative) Thermal equivalent of an intermittent current . 130
Annex J (normative) Electromagnetic compatibility (EMC). 131
J.1 General . 131
Annex K (normative) Operating current and power loss of bare copper bars . 138
Annex L (informative) Guidance on verification of temperature-rise . 141
L.1 General . 141
L.1.1 Principles . 141
L.1.2 Current ratings of assemblies . 141
L.2 Temperature-rise limits . 142
L.3 Test . 143
L.3.1 General . 143
L.3.2 Method a) – Verification of the complete assembly (10.10.2.3.5) . 143
L.3.3 Method b) – Verification considering individual functional units

separately and the complete assembly (10.10.2.3.6) . 143
L.3.4 Method c) – Verification considering individual functional units and the
main and distribution busbars separately as well as the complete
assembly (10.10.2.3.7) . 144
L.4 Verification assessment . 144
L.5 Verification by comparison with a reference design . 144
Annex M (normative) Verification of the short-circuit withstand strength of busbar
structures by comparison with a reference design by calculation . 145
Annex N (informative) List of notes concerning certain countries . 146
Bibliography . 147

Figure 101 – Impact test using striking element . 70
Figure E.1 – Typical assembly . 117
Figure E.2 – Example 1: Table E.1 – Functional unit loading for an assembly with a
rated diversity factor of 0,68 . 119
Figure E.3 – Example 2: Table E.1 – Functional unit loading for an assembly with a

rated diversity factor of 0,6 in Section B and 0,68 in Section C . 120
Figure F.1 – Measurement of clearance and creepage distances . 125
Figure I.1 – Example of average heating effect calculation . 130
Figure J.1 – Examples of ports . 131
Figure L.1 – Not applicable . 144

Table 1 – Minimum clearances in air (8.3.2) . 99
Table 2 – Minimum creepage distances (8.3.3) . 100
Table 3 – Cross-sectional area of a copper protective conductor (8.4.3.2.2) . 101
Table 4 – Conductor selection and installation requirements (8.6.4) . 101
Table 5 – Minimum terminal capacity for copper protective conductors (PE) (8.8) . 101
Table 6 – Temperature-rise limits (9.2) . 102
a
Table 7 – Values for the factor n (9.3.3) . 103
Table 8 – Power-frequency withstand voltage for main circuits (10.9.2) . 103

Table 9 – Power-frequency withstand voltage for auxiliary circuits (10.9.2) . 103
Table 10 – Impulse withstand test voltages (10.9.3) . 103
Table 11 – Copper test conductors for rated currents up to 400 A inclusive
(10.10.2.3.2) . 104
Table 12 – Copper test conductors for rated currents from 400 A to 7 000 A

(10.10.2.3.2) . 105
Table 13 – Short-circuit verification by comparison with reference designs: checklist
(10.5.3.3, 10.11.3 and 10.11.4) . 106
Table 14 – Relationship between prospective fault current and diameter of copper wire . 107
Table 15 – Climatic conditions . 107
Table 101 – Values of assumed loading . 108
Table A.1 – Cross-section of copper cables suitable for connection to terminals for
external cables . 109
Table B.1 – Values of k for insulated protective conductors not incorporated in cables
or bare protective conductors in contact with cable covering . 110
Table C.1 – Items subject to agreement between the assembly manufacturer
and the user . 111
Table D.1 – List of design verifications to be performed . 115
Table E.1 – Examples of loading for an assembly . 118
Table F.1 – Minimum width of grooves . 121
Table G.1 – Correspondence between the nominal voltage of the supply system and
the equipment rated impulse withstand voltage . 127
Table H.1 – Operating current and power loss of single-core copper cables with a
permissible conductor temperature of 70 °C (ambient temperature inside the assembly:
55 °C) . 128
Table H.2 – Reduction factor k for cables with a permissible conductor temperature
of 70 °C (extract from IEC 60364-5-52:2009, Table B.52.14). 129
Table J.1 – Tests for EMC immunity for environment A (see J.10.12.2) . 135
Table J.2 – Tests for EMC immunity for environment B (see J.10.12.2) . 136
Table J.3 – Acceptance criteria when electromagnetic disturbances are present . 137
Table K.1 – Operating current and power loss of bare copper bars with rectangular
cross-section, run horizontally and arranged with their largest face vertical, frequency
50 Hz to 60 Hz (ambient air temperature inside the assembly: 55 °C, temperature of
the conductor 70 °C) . 138
Table K.2 – Factor k for different temperatures of the air inside the assembly and/or
for the conductors . 139

– 8 – IEC 61439-4:2023 EXV © IEC 2023
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR ASSEMBLIES –

Part 1: General rules
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
This extended version (EXV) of the official IEC Standard provides the user with the
comprehensive content of the Standard.
to IEC 61439-1:2020.
The specific content of IEC 61439-4:2023 is displayed on a blue background.

IEC 61439-4 has been prepared by subcommittee 121B: Low-voltage switchgear and
controlgear assemblies, of IEC technical committee 121: Switchgear and controlgear and their
assemblies for low voltage. It is an International Standard.
This second edition of IEC 61439-4 cancels and replaces the first edition published in 2012.
This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) alignment with IEC 61439-1:2020 regarding the structure and technical content, as
applicable.
The text of this document is based on the following documents:
Draft Report on voting
121B/183/FDIS 121B/188/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement,
available at www.iec.ch/members_experts/refdocs. The main document types developed by
IEC are described in greater detail at www.iec.ch/publications.
This document is to be read in conjunction with IEC 61439-1:2020. The provisions of the
general rules dealt with in IEC 61439-1:2020 are only applicable to this document insofar as
they are specifically cited. When this document states “addition”, “modification” or
“replacement”, the relevant text in IEC 61439-1:2020 is to be adapted accordingly.
Subclauses that are numbered with a 101 (102, 103, etc.) suffix are additional to the same
subclause in IEC 61439-1:2020.
Tables and figures in this document that are new are numbered starting with 101.
New annexes in this document are lettered AA, BB, etc.
In this document, terms written in small capitals are defined in Clause 3.
The reader’s attention is drawn to the fact that Annex N lists all of the “in-some-country”
clauses on differing practices of a less permanent nature relating to the subject of this
document.
A list of all parts of the IEC 61439 series, under the general title Low-voltage switchgear and
controlgear assemblies, can be found on the IEC website.

– 10 – IEC 61439-4:2023 EXV © IEC 2023
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be:
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The "colour inside" logo on the cover page of this document indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
INTRODUCTION
The purpose of this document is to harmonize as far as practicable all rules and requirements
of a general nature applicable to low-voltage switchgear and controlgear assemblies, in order
to obtain uniformity of requirements and verification for assemblies and to avoid the need for
verification in other standards. All those requirements for the various assembly standards
which can be considered as general have therefore been gathered in this document together
with specific subjects of wide interest and application, e.g. temperature-rise, dielectric
properties, etc.
For each type of low-voltage switchgear and controlgear assembly, only two main standards
are necessary to determine all requirements and the corresponding methods of verification:
– the basic standard, (this document) referred to as “IEC 61439-1” in the specific standards,
covering the various types of low-voltage switchgear and controlgear assemblies;
– the specific assembly standard hereinafter also referred to as the relevant assembly
standard.
For a general rule to apply to a specific assembly standard, it should be explicitly referred to
by quoting this document followed by the relevant clause or subclause number e.g.
“IEC 61439-1:2020, 9.1.3”.
A specific assembly standard may not require, and hence need not call up, a general rule
where it is not applicable, or it can add requirements if the general rule is deemed inadequate
in the particular case, but it may not deviate from it unless there is substantial technical
justification detailed in the specific assembly standard.
Where, in this document, a cross-reference is made to another clause, the reference is to be
taken to apply to that clause as amended by the specific assembly standard, where applicable.
Requirements in this document that are subject to agreement between the assembly
manufacturer and the user are summarized in Annex C (informative). This schedule also
facilitates the supply of information on basic conditions and additional user specifications to
enable proper design, application and utilization of the assembly.
For the IEC 61439 series, the following parts are published:
a) IEC 61439-1: General rules
b) IEC 61439-2: Power switchgear and controlgear assemblies (PSC-assemblies)
c) IEC 61439-3: Distribution boards intended to be operated by ordinary persons (DBO)
d) IEC 61439-4: Particular requirements for assemblies for construction sites (ACS)
e) IEC 61439-5: Assemblies for power distribution in public networks
f) IEC 61439-6: Busbar trunking systems (busways)
g) IEC 61439-7: Assemblies for specific applications such as marinas, camping sites, market
squares, electric vehicle charging stations
h) IEC TR 61439-0: Guidance to specifying assemblies.
This list is not exhaustive; additional parts can be developed as the need arises.

___________
IEC 61439-2 includes requirements for assemblies for use in photovoltaic installations.

– 12 – IEC 61439-4:2023 EXV © IEC
...

IEC 61439-4 ®
Edition 2.0 2023-10
REDLINE VERSION
INTERNATIONAL
STANDARD
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Low-voltage switchgear and controlgear assemblies –
Part 4: Particular requirements for assemblies for construction sites (ACS)
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IEC 61439-4 ®
Edition 2.0 2023-10
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Low-voltage switchgear and controlgear assemblies –
Part 4: Particular requirements for assemblies for construction sites (ACS)
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.130.20 ISBN 978-2-8322-7708-9

– 2 – IEC 61439-4:2023 RLV © IEC 2023
CONTENTS
FOREWORD . 3
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 Symbols and abbreviations . 9
5 Interface characteristics. 9
6 Information . 10
7 Service conditions . 11
8 Constructional requirements . 12
9 Performance requirements. 14
10 Design verification . 15
11 Routine verification . 17
Annexes . 21
Annex C (informative) User information template . 22
Annex D (informative) Design verification . 26
Annex O L (informative) Guidance on verification of temperature-rise verification . 27
Annex P M (normative) Verification of the short-circuit withstand strength of BUSBAR
structures by comparison with a tested reference design by calculation . 28
Annex AA N (informative) List of notes concerning certain countries . 29
Annex BB (Void) .
Annex CC (informative) Items subject to agreement between the ASSEMBLY
manufacturer and the user .
Bibliography . 35

Figure 101 – Impact test using striking element . 16

Table 101 – Values of assumed loading . 20
Table C.1 – Items subject to agreement between the assembly manufacturer
and the user . 22
Table D.1 – List of design verifications to be performed . 26

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
LOW-VOLTAGE SWITCHGEAR AND
CONTROLGEAR ASSEMBLIES –
Part 4: Particular requirements for assemblies
for construction sites (ACS)
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their
preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
may participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for
Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence between
any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). IEC takes no position concerning the evidence, validity or applicability of any claimed patent rights in
respect thereof. As of the date of publication of this document, IEC had not received notice of (a) patent(s), which
may be required to implement this document. However, implementers are cautioned that this may not represent
the latest information, which may be obtained from the patent database available at https://patents.iec.ch. IEC
shall not be held responsible for identifying any or all such patent rights.
This redline version of the official IEC Standard allows the user to identify the changes
made to the previous edition IEC 61439-4:2012. A vertical bar appears in the margin
wherever a change has been made. Additions are in green text, deletions are in
strikethrough red text.
– 4 – IEC 61439-4:2023 RLV © IEC 2023
IEC 61439-4 has been prepared by subcommittee 121B: Low-voltage switchgear and
controlgear assemblies, of IEC technical committee 121: Switchgear and controlgear and their
assemblies for low voltage. It is an International Standard.
This second edition of IEC 61439-4 cancels and replaces the first edition published in 2012.
This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) alignment with IEC 61439-1:2020 regarding the structure and technical content, as
applicable.
The text of this document is based on the following documents:
Draft Report on voting
121B/183/FDIS 121B/188/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
This document is to be read in conjunction with IEC 61439-1:2020. The provisions of the general
rules dealt with in IEC 61439-1:2020 are only applicable to this document insofar as they are
specifically cited. When this document states “addition”, “modification” or “replacement”, the
relevant text in IEC 61439-1:2020 is to be adapted accordingly.
Subclauses that are numbered with a 101 (102, 103, etc.) suffix are additional to the same
subclause in IEC 61439-1:2020.
Tables and figures in this document that are new are numbered starting with 101.
New annexes in this document are lettered AA, BB, etc.
In this document, terms written in small capitals are defined in Clause 3.
The reader’s attention is drawn to the fact that Annex N lists all of the “in-some-country” clauses
on differing practices of a less permanent nature relating to the subject of this document.
A list of all parts of the IEC 61439 series, under the general title Low-voltage switchgear and
controlgear assemblies, can be found on the IEC website.

The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be:
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The "colour inside" logo on the cover page of this document indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this document using a colour printer.

– 6 – IEC 61439-4:2023 RLV © IEC 2023
LOW-VOLTAGE SWITCHGEAR AND
CONTROLGEAR ASSEMBLIES –
Part 4: Particular requirements for assemblies
for construction sites (ACS)
1 Scope
NOTE Throughout this document, the abbreviation ACS (assembly for construction site, see 3.1.101) is used for a
low-voltage switchgear and controlgear assembly intended for use on construction and similar sites.
This document defines the specific requirements of ACS as follows:
– assemblies for which the rated voltage does not exceed 1 000 V in case of AC or 1 500 V
in case of DC;
– assemblies where the nominal primary voltage and the nominal secondary voltage of
transformers incorporated in ACS are within the limits specified above;
– assemblies intended for use on construction sites, both indoors and outdoors, i.e. temporary
places of work to which the public do not generally have access and where building
construction, installation, repairs, alteration or demolition of property (buildings) or civil
engineering (public works) or excavation or any other similar operations are carried out;
MOBILE assemblies with enclosure.
– transportable (semi-fixed) or
The manufacture and/or assembly may can be carried out by an entity other than by the original
manufacturer (see 3.10.1 of IEC 61439-1:2020).
This document does not apply to individual devices and self-contained components, such as
motor starters, fuse switches, electronic equipment, etc. which will comply with the relevant
product standards.
This document does not apply to assemblies for use in the administrative centres of construction
sites (offices, cloakrooms, ASSEMBLY meeting rooms, canteens, restaurants, dormitories, toilets,
etc.).
Requirements for electrical protection provided by equipment manufactured according to this
document are given in IEC 60364-7-704.
2 Normative references
This clause of IEC 61439-1:2020 is applicable except as follows:
Addition:
IEC 60068-2-27:2008, Environmental testing − Part 2-27: Tests – Test Ea and guidance: Shock
IEC 60068-2-42:2003, Environmental testing − Part 2-42: Tests – Test Kc: Sulphur dioxide test
for contacts and connections
IEC 60364-7-704:20052017, Low-voltage electrical installations − Part 7-704: Requirements for
special installations or locations – Construction and demolition site installations

IEC 61140:2001, Protection against electric shock – Common aspects for installation and
equipment
IEC 61439-1:20112020, Low-voltage switchgear and controlgear assemblies – Part 1: General
rules
IEC 61558-2-23, Safety of transformers, reactors, power supply units and combinations thereof
– Part 2-23: Particular requirements and tests for transformers and power supply units for
construction sites
3 Terms and definitions
This clause of IEC 61439-1:2020 applicable except as follows:
Additional terms and definitions:
3.1 General terms
3.1.101
low-voltage switchgear and controlgear assembly for construction sites
ACS
combination of one or several transforming or low voltage switching devices with associated
control, measuring, signalling, protective and regulating equipment complete with all their
internal electrical and mechanical connections and structural parts, designed and built for use
on all construction sites, indoors and outdoors
3.2 Constructional units of assemblies
3.2.101
metering unit
functional unit equipped with apparatus for metering electrical energy
3.2.102
transformer unit
functional unit consisting mainly of one or several transformers
Modifications:
3.3 External design of assemblies
3.3.1
open-type assembly
This term of IEC 61439-1:2020 does not apply.
3.3.2
dead-front assembly
This term of IEC 61439-1:2020 does not apply.
Replacement:
3.3.3
enclosed ACS
ACS which is enclosed on all sides with the possible exception of its mounting surface in such
a manner as to provide a defined degree of protection

– 8 – IEC 61439-4:2023 RLV © IEC 2023
3.3.7
box-type ACS
ENCLOSED ACS intended:
– either to be mounted on a vertical surface;
– or to stand on a horizontal surface supported by feet or legs (articulated or not) or by a
mounting not forming part of the ACS (see 3.4.2 of IEC 61439-1:2020)
Modification:
3.5 Conditions of installation of assemblies
3.5.1
assembly for indoor installation
This term of IEC 61439-1:2020 does not apply (see 3.1.101).
3.5.2
assembly for outdoor installation
This term of IEC 61439-1:2020 does not apply (see 3.1.101).
3.5.3
stationary assembly
This term of IEC 61439-1:2020 does not apply.
3.5.4
movable assembly
This term of IEC 61439-1:2020 does not apply.
Additional terms and definitions:
3.5.101
transportable ACS
semi-fixed ACS
ACS intended for use in a place where it is not permanently fixed
Note 1 to entry: The location of a TRANSPORTABLE ACS may can vary during work on the same site. When the
equipment is moved to another place, it is first disconnected from the supply.
3.5.102
mobile ACS
ACS capable of being moved as work advances on the site, without being disconnected from
the supply
Additional terms and definitions:
3.101 Function of the ACS
3.101.1
incoming supply function
suitability for connection of the ACS either to electricity public supply network or to the
transformer substation or to on site generator
3.101.2
metering function
suitability for the metering of electrical energy consumed on the site

3.101.3
distribution function
suitability to provide the distribution and protection of electrical supply on the construction site
by means of terminal connection or socket-outlets
3.101.4
transformer function
suitability to provide means for transformer voltages or to provide measures of electrical
protection
Note 1 to entry: Details for their requirements are given in 101.1.
4 Symbols and abbreviations
This clause of IEC 61439-1:2020 is applicable.
5 Interface characteristics
This clause of IEC 61439-1:2020 is applicable, except as follows.
5.3.1 Rated current of an assembly (I )
nA
Replacement of title and text:
5.3.1 Rated current of an ACS (I )
nA
The rated current of an ACS is that group rated current I of its incoming circuit.
ng
This current shall be carried without the temperature rise of the individual parts exceeding the
limits specified in 9.2 of IEC 61439-1:2020.
5.4 Rated diversity factor (RDF)
Addition:
The assumed loading of the outgoing circuits of the ACS or group of outgoing circuits shall be
declared by the assembly manufacturer and may can be based on the values in Table 101.
When the manufacturer does not declare any RDF, the values of Table 101 apply.
5.6 Other characteristics
Replacement:
The following characteristics shall be declared:
a) the function(s) assigned by the manufacturer (see 3.101);
b) the external design (see 3.3);
c) the mobility (see 3.5.101 and 3.5.102);
d) the degree of protection (see 8.2);
e) the method of mounting, for example fixed or removable parts (see 8.5.1 and 8.5.2);
f) protection against electric shock (see 8.4);
g) the resistance to corrosion (see 10.2.2.101);
h) special service conditions, if applicable (see 7.2);

– 10 – IEC 61439-4:2023 RLV © IEC 2023
i) electromagnetic compatibility (EMC) classification (see Annex J of IEC 61439-1:2020).
6 Information
This clause of IEC 61439-1:2020 is applicable except as follows.
6.1 Assembly designation marking
Replacement of title and text:
6.1 ACS designation marking
The assembly manufacturer shall provide each ACS with one or more labels, marked in a
durable manner and located in a place such that they are visible and legible when the ACS is
installed and in operation.
Compliance is checked according to the test of 10.2.7 and by inspection.
The following information regarding the ACS shall be provided on the label(s):
a) assembly manufacturer's name or trade mark (see 3.10.2);
b) type designation or identification number or any other means of identification, making it
possible to obtain relevant information from the assembly manufacturer;
c) means of identifying date of manufacture;
d) IEC 61439-4;
e) type of current (and the frequency in the case of AC);
f) rated voltage (U ) (of the ACS) (see 5.2.1);
n
g) rated current of the ACS (I ) (see 5.3.1);
nA
h) degree of protection (see 8.2);
i) the weight where this exceeds 30 kg.
If the indication of the name or trademark of the manufacturer appears on the ACS, it need shall
not be given on the nameplate.
6.2.1 Information relating to the assembly
Replacement of title and text:
6.2.1 Information relating to the ACS
The following additional information, where applicable, shall be provided in the assembly
manufacturer’s technical documentation supplied with the ACS:
a) rated operational voltage (U ) (of a circuit) (see 5.2.2);
e
b) rated impulse withstand voltage (U ) (see 5.2.4);
imp
c) rated insulation voltage (U ) (see 5.2.3);
i
) (see 5.3.2);
d) rated current of each circuit (I
nc
e) rated peak withstand current (I ) (see 5.3.4);
pk
f) rated short-time withstand current (I ) together with its duration (see 5.3.4);
cw
g) rated conditional short-circuit current (I ) (see 5.3.5);
cc
h) rated frequency (f ) (see 5.5);
n
i) rated diversity factor(s) (RDF) (see 5.4);
j) functions (see 3.101);
k) all necessary information relating to the other declared classifications and characteristics
(see 5.6);
l) the short-circuit withstand strength and characteristics of short-circuit protective device(s)
(see 9.3.2);
m) overall dimensions (including projections e.g handles, covers, doors).
6.2.2 Instructions for handling, installation, operation and maintenance
Addition:
The manufacturer of the ACS should specify in its technical documentation supplied with the
ACS the other types of assemblies which may can be connected to it. This information should
indicate whether the compatibility is based upon the type of system earthing employed and/or
on the need for co-ordination of the electrical protection within the complete installation.
The manufacturer should furnish the appropriate documentation for the purpose to maintain the
protective measures and the co-ordination of the protective devices within the complete
installation.
7 Service conditions
This clause of IEC 61439-1:2020 is applicable except as follows.
Modifications:
7.1.1 Ambient air temperature
This subclause of Part 1 is not applicable.
Replacement of title and text:
7.1.1 Ambient air temperature for ACS installations
The ambient air temperature does not exceed +40 °C and its average over a period of 24 h
does not exceed +35 °C.
The lower limit of the ambient air temperature is –25 °C.
7.1.2 Humidity conditions
This subclause of Part 1 is not applicable.
Replacement of title and text:
7.1.2 Humidity conditions for ACS installations
The relative humidity may temporarily be as high as 100 % at a maximum temperature of
+25 °C.
7.1.32 Pollution degree
Replacement of the last paragraph with:
Only pollution degrees 3 and 4 are applicable.

– 12 – IEC 61439-4:2023 RLV © IEC 2023
The microenvironment may can be reduced to pollution degree 2 if the degree of protection of
the enclosure is at least IP5X and care is taken to avoid condensation.
7.2 Special service conditions
Addition of the following new item:
mn) heavily polluted atmosphere.
8 Constructional requirements
This clause of IEC 61439-1:2020 is applicable except as follows.
8.1.1 General
Addition:
All the apparatus shall be placed inside the enclosure fitted with such removable panels, cover
plates or doors as may be required applicable for connection or maintenance with the possible
exception of the items mentioned in 8.101 provided that they withstand the service conditions
of Clause 7 and the requirements of 8.1.2 and 8.1.6.
8.1.2 Protection against corrosion
Replacement:
Protection against corrosion shall be ensured by the use of suitable materials or by protective
coatings to the exposed surface taking account of the normal service conditions (see 7.1) and/or
special service condition (see 7.2). Compliance to this requirement is checked by the test of
10.2.2.
8.1.4 Resistance to ultra-violet (UV) radiation
Replacement:
For enclosures and external parts made of insulating materials, resistance to ultra-violet
radiation shall be verified according to 10.2.4.
For external parts made of insulating material of components covered by other IEC standard
(for examples socket-outlets, handles of switch, push buttons, etc.), this test is not required.
8.1.5 Mechanical strength
Addition:
The ACS shall be constructed to withstand mechanical shocks having an acceleration of
500 m/s , a pulse shape of a half-sine wave of 11 ms duration (commensurate with equipment
being carried loose in normal road or rail vehicles for long periods).
Compliance is verified according to 10.2.6.
8.1.6 Lifting provision
Replacement:
Lifting rings and/or handles (or any other equivalent system) shall be provided on the ACS and
be firmly attached to the enclosure or supporting framework.

Compliance is checked according to the test of 10.2.5.
8.2.1 Protection against mechanical impact (IK code)
Additional paragraph:
The ACS shall also withstand impacts of 6 joules energy representing collisions with site
construction mechanical handling equipment (see IEC 60068-2-27).
For protection against mechanical impact refer to 10.2.6.
NOTE In addition to 8.2.1, It is possible to make reference also to the IK code in case the enclosure has been
tested according to other IEC 61439 parts.
8.2.2 Protection against contact with live parts, ingress of solid foreign bodies and
water (IP code)
Replacement:
The degree of protection provided by an ACS against contact with live parts, ingress of solid
foreign bodies and water is indicated by the IP code according to IEC 60529 and verified
according to 10.3.
The degree of protection of the ACS shall be at least IP 44, with all doors closed and all
removable panels and cover plates fitted.
Ventilation and drainage holes shall not reduce this degree of protection.
The degree of protection for an operating face inside a door shall be not less than IP 21 provided
that the door can be closed under all conditions of use. Where the door cannot be closed the
degree of protection for the operating face shall be at least IP 44.
Unless otherwise specified, the degree of protection indicated by the original manufacturer
applies to the complete ACS, when it is installed in accordance with the original manufacturer's
instructions.
Socket-outlets not protected by the enclosure of the ACS shall have a degree of protection at
least equivalent to IP 44, both when the plug is removed or fully inserted.
Where the ACS does not have the same IP rating throughout, the original manufacturer shall
declare in its technical documentation supplied with the ACS the IP rating for the separate parts.
Example: IP 44, operating face IP 21.
No IP codes may can be given unless the appropriate verifications have been made according
to 10.3.
8.4.3.1 Installation conditions
Replacement of the first two paragraphs:
The ACS shall include protective measures and be suitable for installations designed to be in
accordance with IEC 60364-7-704:2017.
8.4.4 Protection by total insulation Additional requirements for class II assemblies
e) This item of IEC 61439-1:2020 is not applicable.

– 14 – IEC 61439-4:2023 RLV © IEC 2023
8.4.6.2 Requirements related to accessibility in service by authorized persons
This subclause of IEC 61439-1:2020 is not applicable.
8.5.3 Selection of switching devices and components
Additional paragraphs:
Plugs of different rated currents or voltages shall not be interchangeable, so as to avoid errors
in connecting (see IEC 60309-1 and IEC 60309-2).
Connections for three-phase socket-outlets shall be made in such a way as to retain the same
order of phases.
Additional subclause:
8.5.101 Accessible parts of ACS
Only the socket-outlets, operating handles and control buttons may can be accessible without
the use of a key or tool. The actuator of the main switch shall be easily accessible (see
704.536.2.2 of IEC 60364-7-704:20052017).
8.8 Terminals for external conductors cables
Addition after the third paragraph:
All connections for external cables shall be re-wireable or shall be socket-outlets. Socket-outlets
shall conform with the relevant standards and have a current rating of at least 16 A.
Additional subclauses:
8.101 Supports and securing devices of ACS
Every ACS shall be fitted with supports enabling it to stand on a horizontal surface (e.g. feet or
legs, articulated or not) and/or a system for fixing it to a vertical wall, attached to the enclosure
or supporting framework.
These various supports or securing devices shall be external to the enclosure but firmly
attached to it. They shall be appropriate to the constructional features (weight, environment,
etc.) and service characteristics of the ACS and shall be tested together with the ACS
(Clause 10).
8.102 Cable outlet
The cable outlet shall be at a minimum distance from the ground compatible with the bending
radius of the largest cable that may can be connected to the ACS.
Compliance is checked by inspection.
9 Performance requirements
This clause of IEC 61439-1:2020 is applicable except as follows.
9.3.2 Information concerning short-circuit withstand strength
The last two paragraphs of this subclause of IEC 61439-1:2020 are not applicable.

10 Design verification
This clause of IEC 61439-1:2020 is applicable except as follows.
10.2.1 General
Replacement of the second paragraph:
Where an empty enclosure in accordance with IEC 62208 is used, and it has not been modified
so as to degrade the performance of the enclosure, no repetition of the enclosure testing to
10.2, with the exception of 10.2.6, is required unless the ACS is declared for heavily polluted
atmosphere (see 7.2 item m).
Additional subclause:
10.2.2.101 Verification of the resistance to corrosion in a heavily polluted atmosphere
a) Principle
This test is intended to assess the corrosive effects of an industrial atmosphere, i.e. an
atmosphere polluted with sulphur dioxide.
The complete and fully equipped ACS shall be continuously exposed to this atmosphere for
ten days.
b) Method of test and test atmosphere
The complete and fully equipped ACS shall be tested in accordance with IEC 60068-2-42.
c) Results to be obtained
The ACS is declared satisfactory, if
– no trace of corrosion is found either inside or outside (except for the sharp edges) and;
– no damaging effect appears in the ACS, verified by applying the tests of 10.9.1 of
IEC 61439-1:2020, between 24 h and 36 h after the ACS has been removed from the
test chamber.
10.2.6 Verification of protection against mechanical impact (IK code)
Replacement of title and text:
10.2.6 Verification of mechanical strength
10.2.6.1 General
a) These tests shall be applied to the ACS, the test sample being in working order but
disconnected from the sample supply.
The test sample shall be completely unpackaged.
b) The tests include two distinct procedures:
– impact test;
– shock test.
Tests shall be carried out at an ambient air temperature of (20 ± 5) °C after the ACS has been
kept at this temperature for at least 12 h.
10.2.6.2 Impact test
a) Principle
The complete ACS (with all components mounted inside and fitted on suitable supports and
securing devices (see 8.101) if these form part of the ACS) shall be subjected to a series of
impacts of 6 J applied to the enclosure (not to the components inside it) (see 8.1.6).
b) Method of test
– 16 – IEC 61439-4:2023 RLV © IEC 2023
The equipment to be tested shall be fixed on a support of adequate rigidity to restrict
movement of the ACS to 0,1 mm under the effect of the prescribed impact. Three successive
impacts shall be applied to each face of the ACS under test by means of either:
1) a solid smooth steel sphere approximately 50 mm in diameter and with a mass of
(500 ± 25) g, which shall be allowed to fall freely from rest through a vertical height of
1,2 m onto the enclosure surface held in a horizontal plane. The hardness of the sphere
shall be not less than 50 HR and not more than 58 HR, or
2) a similar steel sphere, shall be suspended by a cord and swing as a pendulum in order
to apply a horizontal impact, falling through a vertical distance of 1,2 m.
See Figure 101 for the test setup.
Sloping surfaces may can be tested using the pendulum but if this is not convenient the
surface will be aligned in the horizontal plane by turning the unit on the support and the
test 1) is used. Before each test an inspection of the sphere shall be made to ensure that it
is free of from burrs and defects.
The test shall be so arranged that the impacts are applied at positions where weaknesses
are most likely to be revealed. A total of 18 impacts shall be applied to the ACS.
The test is not applicable to components such as socket-outlets, operating handles,
illuminating lights, pushbuttons, actuators, etc., when these components are mounted in
recesses with respect to the main surfaces, so that the distance between the most exposed
parts of these components and the said surfaces is at least 1 cm.

Figure 101 – Impact test using striking element
10.2.6.3 Shock test
a) Principle
The ACS shall be subjected to a single pulse half-sine wave, the shock test having a severity
of 500 m/s (50 g) peak acceleration and a duration of 11 ms.
b) Method of test
The ACS in working order shall be tested according to IEC 60068-2-27. Subject to
agreement between manufacturer and user, the test may can be carried out at separate
SECTIONS of the ACS.
10.2.6.4 Results to be obtained
After the test, the enclosure shall continue to provide the degrees of protection specified in
8.2.2; any distortions or deformations of the enclosure and components shall neither be

detrimental to the proper functioning of the ACS nor decrease creepage distances and
clearances to below the required values; actuators, handles, etc., shall still be operable.
Distortion or deformation of plastic parts that can return in correct position by simple action
(such as opening and reclosing of the cover) are not considered to be detrimental to the proper
functioning of the ACS.
Superficial damage, paint removals, small indentations, cracks not visible with normal or
corrected vision without further magnification, or surface cracks shall not constitute failure of
the test.
10.9.3.1 General
Replacement of the first paragraph:
Verification shall be made by test.
10.10.1 General
Modification:
Item c) of this subclause of IEC 61439-1:2020 is not applicable.
10.10.4 Verification assessment
This subclause of IEC 61439-1:2020 is not applicable.
11 Routine verification
This clause of IEC 61439-1:2020 is applicable.
Additional clause:
101 Particular features of ACS
101.1 General requirements and functions
An ACS consists of one incoming unit and one or more outgoing units and may can incorporate
METERING UNIT(s) and TRANSFORMER UNIT(s).
Outgoing unit(s) may can provide different functions such as: supply other ACS, lighting,
machines or electric tools or other construction site equipment.
An ACS may can be intended to be interconnected to form an installation or part of an
installation in the form of a series of ACS. Apart from all their characteristics, they are covered
by the same rules for protection against electric shock and provide, if possible, selective
protection by a suitable choice, for example of breaking capacity, current setting and operating
time.
These various characteristics are laid down by the manufacturer or are the subject of an
agreement between manufacturer and user taking into account the nature of supply and/or
distribution network and relevant installation requirements.
According to the relevant installation standards IEC 60364 series SPDs should be considered
to protect against overvoltages.

– 18 – IEC 61439-4:2023 RLV © IEC 2023
101.2 Incoming unit
The cable connection facilities (terminals, connecting devices, connectors or plug and socket-
outlet accessory) shall be compatible with the current rating of the ACS.
An isolating device and an over-current protective device shall be provided.
There shall be means for securing the isolating device in the open position.
However, the over-current protective device may can be omitted if the ACS is adequately
protected by an over-current protective device located in an upstream (supplying) ACS. In this
case the assembly manufacturer shall provide the relevant information to the user for the correct
choice of the upstream device.
According to IEC 60364-5-53, plug and socket-outlet arrangements may can be used as
isolating devices.
101.3 Metering unit
The METERING UNIT is to shall be designed by or in agreement with the energy suppliers if it is
intended to accept metering device(s) to measure the energy consumed for the purpose of
payment of energy to the said suppliers.
METERING UNITS not intended for the purpose of payment of energy to the suppliers need are
not be necessarily designed by or in agreement with those suppliers.
101.4 Transformer unit
101.4.1 General
This unit may can include a low-voltage/extra low-voltage (LV/ELV) transformer and/or low-
voltage/low-voltage TRANSFORMER UNITS (LV/LV).
101.4.2 LV/ELV unit
This unit may can be either of the LV/SELV or of the LV/PELV type.
The requirements of IEC 61140, IEC 60364-4-41:2005, Clause 441 414 and IEC/TS 61201
apply.
NOTE IEC/TR 61200-704 recommends the use of PELV only for heating concrete.
This type of unit essentially consists of:
a) the protective and control devices in the primary circuit;
b) the transformer, which shall be in accordance with IEC 61558-2-23;
c) the protective and control devices for the output circuit(s).
101.4.3 LV/LV units
The requirements of IEC 60364-4-41:2005, Clause 413 apply.
Each LV/LV unit consists essentially of:
a) the protective and control devices on the primary circuit;
b) the LV/LV transformer, which shall be an isolating transformer in accordance with
IEC 61558-2-23;
c) the protective and control devices for the output circuit(s);

d) the outlets, either terminals or socket-outlets. Socket-outlets shall be protected as required
in 101.5 de).
Notwithstanding item b), the transformer need shall not to be an isolating transformer if the
neutral point is connected by a cable to an earthing terminal outside the enclosure. This cable
shall be identified by a label placed inside the enclosure as close as possible to the terminal.
Also in this case requirements a), c) and d) apply.
101.5 Outgoing units
Each unit consists of one or several outgoing circuits:
a) There shall be means for isolation, load switching, over-current protection and for fault
protection against indirect contact. These functions may can be provided by one or more
devices.
b) The load switching device shall be easily accessible without the use of a key or tool in
normal use.
NOTE 1 This means that an ACS may can have doors closed by key or tools for other purposes (e.g. closing
at the end of working time) and they are opened during the normal use.
c) The switching device shall operate simultaneously on all poles and involve all the phase
conductors. For switching the neutral conductor, see IEC 60364-5-53:20012019,
Clause 536.
d) The connection of the outgoing circuits may can made with socket outlets or by terminals
for direct connection.
e) socket-outlets shall be protected:
– against direct contact or indirect contact according to IEC 60364-7-704:2005,
Clause 704-4;
Where RCD’s are used as means of protection, one RCD may protect several socket-
outlets. However, consideration should be given to the effects of unintended tripping e.g.
when the RCD protects more than 6 socket outlet.
Where RCD are used consideration should be given to the nature of the load e.g. the
presence of high frequency and/or d.c. components.
– against overcurrent with protective devices with a rated current not exceeding the rated
current of the socket-outlet. A protective device may protect more than one socket-outlet
(not applicable to IT systems).
Consideration should be given to effects of unintended tripping e.g. when an overcurrent
protective device protects more than one socket outlet.
Circuits supplying socket-outlets shall be provided with provisions to ensure:
– basic protection or fault protection according to IEC 60364-7-704:2017.
Where RCD’s are used, the same RCD can protect several socket-outlets. However,
consideration should be given to the effects of unintended tripping e.g. when the RCD
protects more than 6 socket outlet;
– the protection against overcurrent with protective devices with a rated current not
exceeding the rated current of the socket-outlet. A protective device can protect more
than one socket-outlet (not applicable to IT systems).
Consideration should be given to effects of unintended tripping e.g. when an overcurrent
protective device protects more than one socket outlet.
NOTE 2 Measures for unwanted tripping are given in Clause 531 of IEC 60364-5-53:2019 and IEC 60364-5-
53:2019/AMD1:2020
Addition:
– 20 – IEC 61439-4:2023 RLV © IEC 2023
Table 101 – Values of assumed loading
Type of load Assumed loading factor
Distribution – 2 and 3 circuits 0,9
Distribution – 4 and 5 circuits 0,8
Distribution – 6 to 9 circuits 0,7
Distribution – 10 or more circuits 0,6

---------
...

IEC 61439-4 ®
Edition 2.0 2023-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Low-voltage switchgear and controlgear assemblies –
Part 4: Particular requirements for assemblies for construction sites (ACS)
Ensembles d'appareillage à basse tension –
Partie 4: Exigences particulières pour ensembles de chantiers (EC)
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IEC 61439-4 ®
Edition 2.0 2023-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Low-voltage switchgear and controlgear assemblies –
Part 4: Particular requirements for assemblies for construction sites (ACS)
Ensembles d'appareillage à basse tension –
Partie 4: Exigences particulières pour ensembles de chantiers (EC)
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.130.20 ISBN 978-2-8322-7538-2
– 2 – IEC 61439-4:2023 © IEC 2023
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 6
4 Symbols and abbreviations . 8
5 Interface characteristics. 8
6 Information . 9
7 Service conditions . 10
8 Constructional requirements . 10
9 Performance requirements. 13
10 Design verification . 13
11 Routine verification . 16
Annexes . 19
Annex C (informative) User information template . 20
Annex D (informative) Design verification . 24
Annex L (informative) Guidance on verification of temperature-rise . 25
Annex M (normative) Verification of the short-circuit withstand strength of BUSBAR
structures by comparison with a reference design by calculation . 26
Annex N (informative) List of notes concerning certain countries . 27
Bibliography . 28

Figure 101 – Impact test using striking element . 15

Table 101 – Values of assumed loading . 18
Table C.1 – Items subject to agreement between the assembly manufacturer
and the user . 20
Table D.1 – List of design verifications to be performed . 24

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
LOW-VOLTAGE SWITCHGEAR AND
CONTROLGEAR ASSEMBLIES –
Part 4: Particular requirements for assemblies
for construction sites (ACS)
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
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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
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any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). IEC takes no position concerning the evidence, validity or applicability of any claimed patent rights in
respect thereof. As of the date of publication of this document, IEC had not received notice of (a) patent(s), which
may be required to implement this document. However, implementers are cautioned that this may not represent
the latest information, which may be obtained from the patent database available at https://patents.iec.ch. IEC
shall not be held responsible for identifying any or all such patent rights.
IEC 61439-4 has been prepared by subcommittee 121B: Low-voltage switchgear and
controlgear assemblies, of IEC technical committee 121: Switchgear and controlgear and their
assemblies for low voltage. It is an International Standard.
This second edition of IEC 61439-4 cancels and replaces the first edition published in 2012.
This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) alignment with IEC 61439-1:2020 regarding the structure and technical content, as
applicable.
– 4 – IEC 61439-4:2023 © IEC 2023
The text of this document is based on the following documents:
Draft Report on voting
121B/183/FDIS 121B/188/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
This document is to be read in conjunction with IEC 61439-1:2020. The provisions of the general
rules dealt with in IEC 61439-1:2020 are only applicable to this document insofar as they are
specifically cited. When this document states “addition”, “modification” or “replacement”, the
relevant text in IEC 61439-1:2020 is to be adapted accordingly.
Subclauses that are numbered with a 101 (102, 103, etc.) suffix are additional to the same
subclause in IEC 61439-1:2020.
Tables and figures in this document that are new are numbered starting with 101.
New annexes in this document are lettered AA, BB, etc.
In this document, terms written in small capitals are defined in Clause 3.
The reader’s attention is drawn to the fact that Annex N lists all of the “in-some-country” clauses
on differing practices of a less permanent nature relating to the subject of this document.
A list of all parts of the IEC 61439 series, under the general title Low-voltage switchgear and
controlgear assemblies, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be:
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
LOW-VOLTAGE SWITCHGEAR AND
CONTROLGEAR ASSEMBLIES –
Part 4: Particular requirements for assemblies
for construction sites (ACS)
1 Scope
NOTE Throughout this document, the abbreviation ACS (assembly for construction site, see 3.1.101) is used for a
low-voltage switchgear and controlgear assembly intended for use on construction and similar sites.
This document defines the specific requirements of ACS as follows:
– assemblies for which the rated voltage does not exceed 1 000 V in case of AC or 1 500 V
in case of DC;
– assemblies where the nominal primary voltage and the nominal secondary voltage of
transformers incorporated in ACS are within the limits specified above;
– assemblies intended for use on construction sites, both indoors and outdoors, i.e. temporary
places of work to which the public do not generally have access and where building
construction, installation, repairs, alteration or demolition of property (buildings) or civil
engineering (public works) or excavation or any other similar operations are carried out;
MOBILE assemblies with enclosure.
– transportable (semi-fixed) or
The manufacture and/or assembly can be carried out by an entity other than by the original
manufacturer (see 3.10.1 of IEC 61439-1:2020).
This document does not apply to individual devices and self-contained components, such as
motor starters, fuse switches, electronic equipment, etc. which will comply with the relevant
product standards.
This document does not apply to assemblies for use in the administrative centres of construction
sites (offices, cloakrooms, meeting rooms, canteens, restaurants, dormitories, toilets, etc.).
Requirements for electrical protection provided by equipment manufactured according to this
document are given in IEC 60364-7-704.
2 Normative references
This clause of IEC 61439-1:2020 is applicable except as follows:
Addition:
IEC 60068-2-27, Environmental testing − Part 2-27: Tests – Test Ea and guidance: Shock
IEC 60068-2-42, Environmental testing − Part 2-42: Tests – Test Kc: Sulphur dioxide test for
contacts and connections
IEC 60364-7-704:2017, Low-voltage electrical installations − Part 7-704: Requirements for
special installations or locations – Construction and demolition site installations
IEC 61439-1:2020, Low-voltage switchgear and controlgear assemblies – Part 1: General rules

– 6 – IEC 61439-4:2023 © IEC 2023
IEC 61558-2-23, Safety of transformers, reactors, power supply units and combinations thereof
– Part 2-23: Particular requirements and tests for transformers and power supply units for
construction sites
3 Terms and definitions
This clause of IEC 61439-1:2020 applicable except as follows:
Additional terms and definitions:
3.1 General terms
3.1.101
low-voltage switchgear and controlgear assembly for construction sites
ACS
combination of one or several transforming or low voltage switching devices with associated
control, measuring, signalling, protective and regulating equipment complete with all their
internal electrical and mechanical connections and structural parts, designed and built for use
on all construction sites, indoors and outdoors
3.2 Constructional units of assemblies
3.2.101
metering unit
functional unit equipped with apparatus for metering electrical energy
3.2.102
transformer unit
functional unit consisting mainly of one or several transformers
Modifications:
3.3 External design of assemblies
3.3.1
open-type assembly
This term of IEC 61439-1:2020 does not apply.
3.3.2
dead-front assembly
This term of IEC 61439-1:2020 does not apply.
Replacement:
3.3.3
enclosed ACS
ACS which is enclosed on all sides with the possible exception of its mounting surface in such
a manner as to provide a defined degree of protection
3.3.7
box-type ACS
ENCLOSED ACS intended:
– either to be mounted on a vertical surface;
– or to stand on a horizontal surface supported by feet or legs (articulated or not) or by a
mounting not forming part of the ACS (see 3.4.2 of IEC 61439-1:2020)

Modification:
3.5 Conditions of installation of assemblies
3.5.1
assembly for indoor installation
This term of IEC 61439-1:2020 does not apply (see 3.1.101).
3.5.2
assembly for outdoor installation
This term of IEC 61439-1:2020 does not apply (see 3.1.101).
3.5.3
stationary assembly
This term of IEC 61439-1:2020 does not apply.
3.5.4
movable assembly
This term of IEC 61439-1:2020 does not apply.
Additional terms and definitions:
3.5.101
transportable ACS
semi-fixed ACS
ACS intended for use in a place where it is not permanently fixed
Note 1 to entry: The location of a TRANSPORTABLE ACS can vary during work on the same site. When the equipment
is moved to another place, it is first disconnected from the supply.
3.5.102
mobile ACS
ACS capable of being moved as work advances on the site, without being disconnected from
the supply
Additional terms and definitions:
3.101 Function of the ACS
3.101.1
incoming supply function
suitability for connection of the ACS either to electricity public supply network or to the
transformer substation or to on site generator
3.101.2
metering function
suitability for the metering of electrical energy consumed on the site
3.101.3
distribution function
suitability to provide the distribution and protection of electrical supply on the construction site
by means of terminal connection or socket-outlets

– 8 – IEC 61439-4:2023 © IEC 2023
3.101.4
transformer function
suitability to provide means for transformer voltages or to provide measures of electrical
protection
Note 1 to entry: Details for their requirements are given in 101.1.
4 Symbols and abbreviations
This clause of IEC 61439-1:2020 is applicable.
5 Interface characteristics
This clause of IEC 61439-1:2020 is applicable, except as follows.
)
5.3.1 Rated current of an assembly (I
nA
Replacement of title and text:
5.3.1 Rated current of an ACS (I )
nA
The rated current of an ACS is group rated current I of its incoming circuit.
ng
This current shall be carried without the temperature rise of the individual parts exceeding the
limits specified in 9.2 of IEC 61439-1:2020.
5.4 Rated diversity factor (RDF)
Addition:
The assumed loading of the outgoing circuits of the ACS or group of outgoing circuits shall be
declared by the assembly manufacturer and can be based on the values in Table 101.
When the manufacturer does not declare any RDF, the values of Table 101 apply.
5.6 Other characteristics
Replacement:
The following characteristics shall be declared:
a) the function(s) assigned by the manufacturer (see 3.101);
b) the external design (see 3.3);
c) the mobility (see 3.5.101 and 3.5.102);
d) the degree of protection (see 8.2);
e) the method of mounting, for example fixed or removable parts (see 8.5.1 and 8.5.2);
f) protection against electric shock (see 8.4);
g) the resistance to corrosion (see 10.2.2.101);
h) special service conditions, if applicable (see 7.2);
i) electromagnetic compatibility (EMC) classification (see Annex J of IEC 61439-1:2020).

6 Information
This clause of IEC 61439-1:2020 is applicable except as follows.
6.1 Assembly designation marking
Replacement of title and text:
6.1 ACS designation marking
The assembly manufacturer shall provide each ACS with one or more labels, marked in a
durable manner and located in a place such that they are visible and legible when the ACS is
installed and in operation.
Compliance is checked according to the test of 10.2.7 and by inspection.
The following information regarding the ACS shall be provided on the label(s):
a) assembly manufacturer's name or trade mark (see 3.10.2);
b) type designation or identification number or any other means of identification, making it
possible to obtain relevant information from the assembly manufacturer;
c) means of identifying date of manufacture;
d) IEC 61439-4;
e) type of current (and the frequency in the case of AC);
f) rated voltage (U ) (of the ACS) (see 5.2.1);
n
g) rated current of the ACS (I ) (see 5.3.1);
nA
h) degree of protection (see 8.2);
i) the weight where this exceeds 30 kg.
If the indication of the name or trademark of the manufacturer appears on the ACS, it shall not
be given on the nameplate.
6.2.1 Information relating to the assembly
Replacement of title and text:
6.2.1 Information relating to the ACS
The following additional information, where applicable, shall be provided in the assembly
manufacturer’s technical documentation supplied with the ACS:
a) rated operational voltage (U ) (of a circuit) (see 5.2.2);
e
b) rated impulse withstand voltage (U ) (see 5.2.4);
imp
c) rated insulation voltage (U ) (see 5.2.3);
i
d) rated current of each circuit (I ) (see 5.3.2);
nc
e) rated peak withstand current (I ) (see 5.3.4);
pk
f) rated short-time withstand current (I ) together with its duration (see 5.3.4);
cw
g) rated conditional short-circuit current (I ) (see 5.3.5);
cc
h) rated frequency (f ) (see 5.5);
n
i) rated diversity factor(s) (RDF) (see 5.4);
j) functions (see 3.101);
– 10 – IEC 61439-4:2023 © IEC 2023
k) all necessary information relating to the other declared classifications and characteristics
(see 5.6);
l) the short-circuit withstand strength and characteristics of short-circuit protective device(s)
(see 9.3.2);
m) overall dimensions (including projections e.g handles, covers, doors).
6.2.2 Instructions for handling, installation, operation and maintenance
Addition:
The manufacturer of the ACS should specify in its technical documentation supplied with the
ACS the other types of assemblies which can be connected to it. This information should
indicate whether the compatibility is based upon the type of system earthing employed and/or
on the need for co-ordination of the electrical protection within the complete installation.
The manufacturer should furnish the appropriate documentation for the purpose to maintain the
protective measures and the co-ordination of the protective devices within the complete
installation.
7 Service conditions
This clause of IEC 61439-1:2020 is applicable except as follows.
Modifications:
7.1.2 Pollution degree
Replacement of the last paragraph with:
Only pollution degrees 3 and 4 are applicable.
The microenvironment can be reduced to pollution degree 2 if the degree of protection of the
enclosure is at least IP5X and care is taken to avoid condensation.
7.2 Special service conditions
Addition of the following new item:
n) heavily polluted atmosphere.
8 Constructional requirements
This clause of IEC 61439-1:2020 is applicable except as follows.
8.1.1 General
Addition:
All the apparatus shall be placed inside the enclosure fitted with such removable panels, cover
plates or doors as applicable for connection or maintenance with the possible exception of the
items mentioned in 8.101 provided that they withstand the service conditions of Clause 7 and
the requirements of 8.1.2 and 8.1.6.

8.1.2 Protection against corrosion
Replacement:
Protection against corrosion shall be ensured by the use of suitable materials or by protective
coatings to the exposed surface taking account of the normal service conditions (see 7.1) and/or
special service condition (see 7.2). Compliance to this requirement is checked by the test of
10.2.2.
8.1.4 Resistance to ultra-violet (UV) radiation
Replacement:
For enclosures and external parts made of insulating materials, resistance to ultra-violet
radiation shall be verified according to 10.2.4.
For external parts made of insulating material of components covered by other IEC standard
(for examples socket-outlets, handles of switch, push buttons, etc.), this test is not required.
8.1.5 Mechanical strength
Addition:
The ACS shall be constructed to withstand mechanical shocks having an acceleration of
500 m/s , a pulse shape of a half-sine wave of 11 ms duration (commensurate with equipment
being carried loose in normal road or rail vehicles for long periods).
Compliance is verified according to 10.2.6.
8.1.6 Lifting provision
Replacement:
Lifting rings and/or handles (or any other equivalent system) shall be provided on the ACS and
be firmly attached to the enclosure or supporting framework.
Compliance is checked according to the test of 10.2.5.
8.2.1 Protection against mechanical impact (IK code)
Additional paragraph:
The ACS shall also withstand impacts of 6 joules energy representing collisions with site
construction mechanical handling equipment (see IEC 60068-2-27).
For protection against mechanical impact refer to 10.2.6.
NOTE In addition to 8.2.1, It is possible to make reference also to the IK code in case the enclosure has been
tested according to other IEC 61439 parts.
8.2.2 Protection against contact with live parts, ingress of solid foreign bodies and
water (IP code)
Replacement:
The degree of protection provided by an ACS against contact with live parts, ingress of solid
foreign bodies and water is indicated by the IP code according to IEC 60529 and verified
according to 10.3.
– 12 – IEC 61439-4:2023 © IEC 2023
The degree of protection of the ACS shall be at least IP 44, with all doors closed and all
removable panels and cover plates fitted.
Ventilation and drainage holes shall not reduce this degree of protection.
The degree of protection for an operating face inside a door shall be not less than IP 21 provided
that the door can be closed under all conditions of use. Where the door cannot be closed the
degree of protection for the operating face shall be at least IP 44.
Unless otherwise specified, the degree of protection indicated by the original manufacturer
applies to the complete ACS, when it is installed in accordance with the original manufacturer's
instructions.
Socket-outlets not protected by the enclosure of the ACS shall have a degree of protection at
least equivalent to IP 44, both when the plug is removed or fully inserted.
Where the ACS does not have the same IP rating throughout, the original manufacturer shall
declare in its technical documentation supplied with the ACS the IP rating for the separate parts.
Example: IP 44, operating face IP 21.
No IP codes can be given unless the appropriate verifications have been made according to
10.3.
8.4.3.1 Installation conditions
Replacement of the first two paragraphs:
The ACS shall include protective measures and be suitable for installations designed to be in
accordance with IEC 60364-7-704:2017.
8.4.4 Additional requirements for class II assemblies
e) This item of IEC 61439-1:2020 is not applicable.
8.4.6.2 Requirements related to accessibility in service by authorized persons
This subclause of IEC 61439-1:2020 is not applicable.
8.5.3 Selection of switching devices and components
Additional paragraphs:
Plugs of different rated currents or voltages shall not be interchangeable, so as to avoid errors
in connecting (see IEC 60309-1 and IEC 60309-2).
Connections for three-phase socket-outlets shall be made in such a way as to retain the same
order of phases.
Additional subclause:
8.5.101 Accessible parts of ACS
Only the socket-outlets, operating handles and control buttons can be accessible without the
use of a key or tool. The actuator of the main switch shall be easily accessible (see 704.536.2.2
of IEC 60364-7-704:2017).
8.8 Terminals for external cables
Addition after the third paragraph:
All connections for external cables shall be re-wireable or shall be socket-outlets. Socket-outlets
shall conform with the relevant standards and have a current rating of at least 16 A.
Additional subclauses:
8.101 Supports and securing devices of ACS
Every ACS shall be fitted with supports enabling it to stand on a horizontal surface (e.g. feet or
legs, articulated or not) and/or a system for fixing it to a vertical wall, attached to the enclosure
or supporting framework.
These various supports or securing devices shall be external to the enclosure but firmly
attached to it. They shall be appropriate to the constructional features (weight, environment,
etc.) and service characteristics of the ACS and shall be tested together with the ACS
(Clause 10).
8.102 Cable outlet
The cable outlet shall be at a minimum distance from the ground compatible with the bending
radius of the largest cable that can be connected to the ACS.
Compliance is checked by inspection.
9 Performance requirements
This clause of IEC 61439-1:2020 is applicable except as follows.
9.3.2 Information concerning short-circuit withstand strength
The last two paragraphs of this subclause of IEC 61439-1:2020 are not applicable.
10 Design verification
This clause of IEC 61439-1:2020 is applicable except as follows.
10.2.1 General
Replacement of the second paragraph:
Where an empty enclosure in accordance with IEC 62208 is used, and it has not been modified
so as to degrade the performance of the enclosure, no repetition of the enclosure testing to
10.2, with the exception of 10.2.6, is required unless the ACS is declared for heavily polluted
atmosphere (see 7.2 item m).
Additional subclause:
– 14 – IEC 61439-4:2023 © IEC 2023
10.2.2.101 Verification of the resistance to corrosion in a heavily polluted atmosphere
a) Principle
This test is intended to assess the corrosive effects of an industrial atmosphere, i.e. an
atmosphere polluted with sulphur dioxide.
The complete and fully equipped ACS shall be continuously exposed to this atmosphere for
ten days.
b) Method of test and test atmosphere
The complete and fully equipped ACS shall be tested in accordance with IEC 60068-2-42.
c) Results to be obtained
The ACS is declared satisfactory, if
– no trace of corrosion is found either inside or outside (except for the sharp edges) and;
– no damaging effect appears in the ACS, verified by applying the tests of 10.9.1 of
IEC 61439-1:2020, between 24 h and 36 h after the ACS has been removed from the
test chamber.
10.2.6 Verification of protection against mechanical impact (IK code)
Replacement of title and text:
10.2.6 Verification of mechanical strength
10.2.6.1 General
a) These tests shall be applied to the ACS, the test sample being in working order but
disconnected from the sample supply.
The test sample shall be completely unpackaged.
b) The tests include two distinct procedures:
– impact test;
– shock test.
Tests shall be carried out at an ambient air temperature of (20 ± 5) °C after the ACS has been
kept at this temperature for at least 12 h.
10.2.6.2 Impact test
a) Principle
The complete ACS (with all components mounted inside and fitted on suitable supports and
securing devices (see 8.101) if these form part of the ACS) shall be subjected to a series of
impacts of 6 J applied to the enclosure (not to the components inside it) (see 8.1.6).
b) Method of test
The equipment to be tested shall be fixed on a support of adequate rigidity to restrict
movement of the ACS to 0,1 mm under the effect of the prescribed impact. Three successive
impacts shall be applied to each face of the ACS under test by means of either:
1) a solid smooth steel sphere approximately 50 mm in diameter and with a mass of
(500 ± 25) g, which shall be allowed to fall freely from rest through a vertical height of
1,2 m onto the enclosure surface held in a horizontal plane. The hardness of the sphere
shall be not less than 50 HR and not more than 58 HR, or
2) a similar steel sphere, shall be suspended by a cord and swing as a pendulum in order
to apply a horizontal impact, falling through a vertical distance of 1,2 m.
See Figure 101 for the test setup.
Sloping surfaces can be tested using the pendulum but if this is not convenient the surface
will be aligned in the horizontal plane by turning the unit on the support and the test 1) is
used. Before each test an inspection of the sphere shall be made to ensure that it is free
from burrs and defects.
The test shall be so arranged that the impacts are applied at positions where weaknesses
are most likely to be revealed. A total of 18 impacts shall be applied to the ACS.
The test is not applicable to components such as socket-outlets, operating handles,
illuminating lights, pushbuttons, actuators, etc., when these components are mounted in
recesses with respect to the main surfaces, so that the distance between the most exposed
parts of these components and the said surfaces is at least 1 cm.

Figure 101 – Impact test using striking element
10.2.6.3 Shock test
a) Principle
The ACS shall be subjected to a single pulse half-sine wave, the shock test having a severity
of 500 m/s (50 g) peak acceleration and a duration of 11 ms.
b) Method of test
The ACS in working order shall be tested according to IEC 60068-2-27. Subject to
agreement between manufacturer and user, the test can be carried out at separate SECTIONS
of the ACS.
10.2.6.4 Results to be obtained
After the test, the enclosure shall continue to provide the degrees of protection specified in
8.2.2; any distortions or deformations of the enclosure and components shall neither be
detrimental to the proper functioning of the ACS nor decrease creepage distances and
clearances to below the required values; actuators, handles, etc., shall still be operable.
Distortion or deformation of plastic parts that can return in correct position by simple action
(such as opening and reclosing of the cover) are not considered to be detrimental to the proper
functioning of the ACS.
Superficial damage, paint removals, small indentations, cracks not visible with normal or
corrected vision without further magnification, or surface cracks shall not constitute failure of
the test.
10.9.3.1 General
Replacement of the first paragraph:
Verification shall be made by test.

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10.10.1 General
Modification:
Item c) of this subclause of IEC 61439-1:2020 is not applicable.
10.10.4 Verification assessment
This subclause of IEC 61439-1:2020 is not applicable.
11 Routine verification
This clause of IEC 61439-1:2020 is applicable.
Additional clause:
101 Particular features of ACS
101.1 General requirements and functions
An ACS consists of one incoming unit and one or more outgoing units and can incorporate
METERING UNIT(s) and TRANSFORMER UNIT(s).
Outgoing unit(s) can provide different functions such as: supply other ACS, lighting, machines
or electric tools or other construction site equipment.
An ACS can be intended to be interconnected to form an installation or part of an installation in
the form of a series of ACS. Apart from all their characteristics, they are covered by the same
rules for protection against electric shock and provide, if possible, selective protection by a
suitable choice, for example of breaking capacity, current setting and operating time.
These various characteristics are laid down by the manufacturer or are the subject of an
agreement between manufacturer and user taking into account the nature of supply and/or
distribution network and relevant installation requirements.
According to the relevant installation standards IEC 60364 series SPDs should be considered
to protect against overvoltages.
101.2 Incoming unit
The cable connection facilities (terminals, connecting devices, connectors or plug and socket-
outlet accessory) shall be compatible with the current rating of the ACS.
An isolating device and an over-current protective device shall be provided.
There shall be means for securing the isolating device in the open position.
However, the over-current protective device can be omitted if the ACS is adequately protected
by an over-current protective device located in an upstream (supplying) ACS. In this case the
assembly manufacturer shall provide the relevant information to the user for the correct choice
of the upstream device.
According to IEC 60364-5-53, plug and socket-outlet arrangements can be used as isolating
devices.
101.3 Metering unit
The METERING UNIT shall be designed by or in agreement with the energy suppliers if it is
intended to accept metering device(s) to measure the energy consumed for the purpose of
payment of energy to the said suppliers.
METERING UNITS not intended for the purpose of payment of energy to the suppliers are not
necessarily designed by or in agreement with those suppliers.
101.4 Transformer unit
101.4.1 General
This unit can include a low-voltage/extra low-voltage (LV/ELV) transformer and/or low-
voltage/low-voltage TRANSFORMER UNITS (LV/LV).
101.4.2 LV/ELV unit
This unit can be either of the LV/SELV or of the LV/PELV type.
The requirements of IEC 60364-4-41:2005, Clause 414 apply.
This type of unit essentially consists of:
a) the protective and control devices in the primary circuit;
b) the transformer, which shall be in accordance with IEC 61558-2-23;
c) the protective and control devices for the output circuit(s).
101.4.3 LV/LV units
The requirements of IEC 60364-4-41:2005, Clause 413 apply.
Each LV/LV unit consists essentially of:
a) the protective and control devices on the primary circuit;
b) the LV/LV transformer, which shall be an isolating transformer in accordance with
IEC 61558-2-23;
c) the protective and control devices for the output circuit(s);
d) the outlets, either terminals or socket-outlets. Socket-outlets shall be protected as required
in 101.5 e).
Notwithstanding item b), the transformer shall not be an isolating transformer if the neutral point
is connected by a cable to an earthing terminal outside the enclosure. This cable shall be
identified by a label placed inside the enclosure as close as possible to the terminal. Also in
this case requirements a), c) and d) apply.
101.5 Outgoing units
Each unit consists of one or several outgoing circuits:
a) There shall be means for isolation, load switching, over-current protection and for fault
protection. These functions can be provided by one or more devices.
b) The load switching device shall be easily accessible without the use of a key or tool in
normal use.
NOTE 1 This means that an ACS can have doors closed by key or tools for other purposes (e.g. closing at the
end of working time) and they are opened during the normal use.

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c) The switching device shall operate simultaneously on all poles and involve all the phase
conductors. For switching the neutral conductor, see IEC 60364-5-53:2019, Clause 536.
d) The connection of the outgoing circuits can made with socket outlets or by terminals for
direct connection.
e) Circuits supplying socket-outlets shall be provided with provisions to ensure:
– basic protection or fault protection according to IEC 60364-7-704:2017.
Where RCD’s are used, the same RCD can protect several socket-outlets. However,
consideration should be given to the effects of unintended tripping e.g. when the RCD
protects more than 6 socket outlet;
– the protection against overcurrent with protective devices with a rated current not
exceeding the rated current of the socket-outlet. A protective device can protect more
than one socket-outlet (not applicable to IT systems).
Consideration should be given to effects of unintended tripping e.g. when an overcurrent
protective device protects more than one socket outlet.
NOTE 2 Measures for unwanted tripping are given in Clause 531 of IEC 60364-5-53:2019 and IEC 60364-5-
53:2019/AMD1:2020
Addition:
Table 101 – Values of assumed loading
Type of load Assumed loading factor
Distribution – 2 and 3 circuits 0,9
Distribution – 4 and 5 circuits 0,8
Distribution – 6 to 9 circuits 0,7
Distribution – 10 or more circuits 0,6

Annexes
The annexes of IEC 61439-1:2020 are applicable except as follows:

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Annex C
(informative)
User information templat
...