IEC 61439-1:2020

IEC 61439-1 ®
Edition 3.0 2020-05
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Low-voltage switchgear and controlgear assemblies –
Part 1: General rules
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IEC 61439-1 ®
Edition 3.0 2020-05
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Low-voltage switchgear and controlgear assemblies –

Part 1: General rules
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.130.20 ISBN 978-2-8322-8337-0

– 2 – IEC 61439-1:2020 RLV © IEC 2020
CONTENTS
FOREWORD . 8
INTRODUCTION . 10
1 Scope . 11
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 . 21
3.6 Insulation characteristics . 22
3.7 Protection against electric shock . 25
3.8 Characteristics . 29
3.9 Verification . 33
3.10 Manufacturer . 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) . 35
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 assembly (I ) . 36
nA
5.3.2 Rated current of a main outgoing circuit (I ) . 37
nc
5.3.3 Group rated current of a main circuit (I ) . 37
ng
5.3.4 Rated peak withstand current (I ) . 38
pk
5.3.5 Rated short-time withstand current (I ) (of a main circuit of an
cw
assembly) . 38
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 ) . 39
n
5.6 Other characteristics . 39
6 Information . 40
6.1 Assembly designation marking . 40
6.2 Documentation . 40
6.2.1 Information relating to the assembly . 40
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
Ambient air temperature .
Humidity conditions .

7.1.2 Pollution degree . 42
Altitude .
7.2 Special service conditions . 43
7.3 Conditions during transport, storage and installation . 43
8 Constructional requirements . 43
8.1 Strength of materials and parts . 43
8.1.1 General . 43
8.1.2 Protection against corrosion . 44
8.1.3 Properties of insulating materials . 44
8.1.4 Resistance to ultra-violet (UV) radiation . 45
8.1.5 Mechanical strength . 45
8.1.6 Lifting provision . 45
8.2 Degree of protection provided by an assembly enclosure . 45
8.2.1 Protection against mechanical impact (IK code) . 45
8.2.2 Protection against contact with live parts, ingress of solid foreign bodies

and water (IP code) . 46
8.2.3 Assembly with removable parts. 46
8.3 Clearances and creepage distances. 47
8.3.1 General . 47
8.3.2 Clearances . 47
8.3.3 Creepage distances . 48
8.4 Protection against electric shock . 48
8.4.1 General . 48
8.4.2 Basic protection . 48
8.4.3 Fault protection . 49
8.4.4 Protection by total insulation Additional requirements for class II
assemblies . 52
8.4.5 Limitation of steady-state touch currents and charge . 54
8.4.6 Operating and servicing conditions . 54
8.5 Incorporation of switching devices and components . 56
8.5.1 Fixed parts . 56
8.5.2 Removable parts . 56
8.5.3 Selection of switching devices and components . 56
8.5.4 Installation of switching devices and components . 57
8.5.5 Accessibility . 57
8.5.6 Barriers . 58
8.5.7 Direction of operation and indication of switching positions . 58
8.5.8 Indicator lights and push-buttons . 58
8.5.9 Power factor correction banks . 58
8.6 Internal electrical circuits and connections . 58
8.6.1 Main circuits . 58
8.6.2 Auxiliary circuits . 59
8.6.3 Bare and insulated conductors . 59
8.6.4 Selection and installation of non-protected live conductors to reduce the
possibility of short-circuits . 60
8.6.5 Identification of the conductors of main and auxiliary circuits . 60
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 . 60

– 4 – IEC 61439-1:2020 RLV © IEC 2020
8.6.7 Conductors in AC circuits passing through ferromagnetic enclosures or
plates . 61
8.7 Cooling . 61
8.8 Terminals for external conductors cables . 61
9 Performance requirements . 63
9.1 Dielectric properties . 63
9.1.1 General . 63
9.1.2 Power-frequency withstand voltage . 63
9.1.3 Impulse withstand voltage . 63
9.1.4 Protection of surge protective devices . 64
9.2 Temperature-rise limits . 64
9.2.1 General . 64
9.2.2 Adjustment of rated currents for alternative ambient air temperatures . 64
9.3 Short-circuit protection and short-circuit withstand strength . 65
9.3.1 General . 65
9.3.2 Information concerning short-circuit withstand strength . 65
9.3.3 Relationship between peak current and short-time current . 66
9.3.4 Coordination of protective devices . 66
9.4 Electromagnetic compatibility (EMC) . 66
10 Design verification . 67
10.1 General . 67
10.2 Strength of materials and parts . 68
10.2.1 General . 68
10.2.2 Resistance to corrosion . 68
10.2.3 Properties of insulating materials . 70
10.2.4 Resistance to ultraviolet (UV) radiation . 72
10.2.5 Lifting . 73
10.2.6 Verification of protection against mechanical impact (IK code) . 74
10.2.7 Marking . 74
10.2.8 Mechanical operation . 74
10.3 Degree of protection of assemblies (IP Code) . 75
10.4 Clearances and creepage distances. 76
10.5 Protection against electric shock and integrity of protective circuits . 76
10.5.1 Effectiveness of the protective circuit General . 76
10.5.2 Effective earth continuity between the exposed-conductive-parts of the
class I assembly and the protective circuit . 76
10.5.3 Short-circuit withstand strength of the protective circuit . 76
10.6 Incorporation of switching devices and components . 77
10.6.1 General . 77
10.6.2 Electromagnetic compatibility . 77
10.7 Internal electrical circuits and connections . 77
10.8 Terminals for external conductors . 77
10.9 Dielectric properties . 78
10.9.1 General . 78
10.9.2 Power-frequency withstand voltage . 78
10.9.3 Impulse withstand voltage . 79
10.9.4 Testing of enclosures made of insulating material . 81
10.9.5 External door or cover mounted operating handles of insulating material . 81

10.9.6 Testing of conductors and hazardous live parts covered by insulating
material to provide protection against electric shock . 81
10.10 Verification of Temperature-rise . 82
10.10.1 General . 82
10.10.2 Verification by testing . 82
10.10.3 Derivation of ratings for similar variants Verification by comparison . 89
10.10.4 Verification assessment . 92
10.11 Short-circuit withstand strength . 96
10.11.1 General . 96
10.11.2 Circuits of assemblies which are exempted from the verification of the
short-circuit withstand strength . 97
10.11.3 Verification by comparison with a reference design – Using a checklist . 97
10.11.4 Verification by comparison with a reference design(s) – Using
calculation . 97
10.11.5 Verification by test . 98
10.12 Electromagnetic compatibility (EMC) . 104
Mechanical operation .
11 Routine verification . 105
11.1 General . 105
11.2 Degree of protection against contact with hazardous live parts, ingress of
solid foreign bodies and water of enclosures . 105
11.3 Clearances and creepage distances. 105
11.4 Protection against electric shock and integrity of protective circuits . 106
11.5 Incorporation of built-in components . 106
11.6 Internal electrical circuits and connections . 106
11.7 Terminals for external conductors . 106
11.8 Mechanical operation . 106
11.9 Dielectric properties . 106
11.10 Wiring, operational performance and function . 107
Annex A (normative) Minimum and maximum cross-section of copper conductors
cables suitable for connection to terminals for external conductors cables (see 8.8) . 117
Annex B (normative) Method of calculating the cross-sectional area of protective
conductors with regard to thermal stresses due to currents of short duration . 118
Annex C (informative) User information template . 119
Annex D (informative) Design verification . 123
Annex E (informative) Rated diversity factor . 125
Annex F (normative) Measurement of clearances and creepage distances . 138
Annex G (normative) Correlation between the nominal voltage of the supply system
and the rated impulse withstand voltage of the equipment . 143
Annex H (informative) Operating current and power loss of copper conductors cables . 145
Annex I (informative) Thermal equivalent of an intermittent current . 149
Annex K (normative) Protection by electrical separation.
Annex L (informative) Clearances and creepage distances for North American region .
Annex M (informative) North American temperature rise limits .
Annex J (normative) Electromagnetic compatibility (EMC). 150
Annex K (normative) Operating current and power loss of bare copper bars . 163
Annex L (informative) Guidance on verification of temperature-rise . 166

– 6 – IEC 61439-1:2020 RLV © IEC 2020
Annex M (normative) Verification of the short-circuit withstand strength of busbar
structures by comparison with a tested reference design by calculation . 173
Annex N (informative) List of notes concerning certain countries . 178

Bibliography . 184
Figure E.1 – Typical assembly . 134
Figure E.2 – Example 1: Table E.1 – Functional unit loading for an assembly
with a rated diversity factor of 0,68 . 136
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 . 137
Figure F.1 – Measurement of ribs clearance and creepage distances . 142
Figure I.1 – Example of average heating effect calculation . 149
Figure J.1 – Examples of ports . 150
Figure L.1 – Verification of temperature-rise . 172
Figure M.1 – Tested busbar structure (TS) . 174
Figure M.2 – Non tested busbar structure (NTS) . 175
Figure M.3 – Angular busbar configuration with supports at the corners . 176

Table 1 – Minimum clearances in air (8.3.2) . 107
Table 2 – Minimum creepage distances (8.3.3) . 108
Table 3 – Cross-sectional area of a copper protective conductor (8.4.3.2.2) . 109
Table 4 – Conductor selection and installation requirements (8.6.4) . 109
Table 5 – Minimum terminal capacity for copper protective conductors (PE, PEN (8.8) . 110
Table 6 – Temperature-rise limits (9.2) . 110
a
Table 7 – Values for the factor n (9.3.3) . 111
Table 8 – Power-frequency withstand voltage for main circuits (10.9.2) . 112
Table 9 – Power-frequency withstand voltage for auxiliary and control circuits (10.9.2) . 112
Table 10 – Impulse withstand test voltages (10.9.3) . 112
Table 11 – Copper test conductors for rated currents up to 400 A inclusive
(10.10.2.3.2) . 113
Table 12 – Copper test conductors for rated currents from 400 A to 4 000 7 000 A
(10.10.2.3.2) . 114
Table 13 – Short-circuit verification by comparison with reference designs: checklist
(10.5.3.3, 10.11.3 and 10.11.4) . 115
Table 14 – Relationship between prospective fault current and diameter of copper wire . 116
Table 15 – Climatic conditions . 116
Table A.1 – Cross-section of copper conductors cables suitable for connection
to terminals for external conductors cables . 117
Table B.1 – Values of k for insulated protective conductors not incorporated in cables
or bare protective conductors in contact with cable covering . 118
Table C.1 – User information template . 119
Table D.1 – List of design verifications to be performed . 123
Table E.1 – Examples of loading for an assembly . 135
Table F.1 – Minimum width of grooves . 138
Table G.1 – Correspondence between the nominal voltage of the supply system and
the equipment rated impulse withstand voltage . 144

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) . 145
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). 146
Table J.1 – Tests for EMC immunity for environment A (see J.10.12.2) . 154
Table J.2 – Tests for EMC immunity for environment B (see J.10.12.2) . 155
Table J.3 – Acceptance criteria when electromagnetic disturbances are present . 157
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) . 163
Table K.2 – Factor k for different temperatures of the air inside the assembly and/or
for the conductors . 164

– 8 – IEC 61439-1:2020 RLV © IEC 2020
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
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5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
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6) All users should ensure that they have the latest edition of this publication.
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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
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This redline version of the official IEC Standard allows the user to identify the changes
made to the previous edition. A vertical bar appears in the margin wherever a change
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International Standard IEC 61439-1 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.
This third edition cancels and replaces the second edition published in 2011. It constitutes a
technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) clarification that power electric converter systems, switch mode power supplies,
uninterruptable power supplies and adjustable speed power drive systems are tested to
their particular products standard, but when they are incorporated in assemblies the
incorporation is in accordance with the IEC 61439 series of standards;
b) introduction of a group rated current for circuits within a loaded assembly and the
refocusing of temperature-rise verification on this new characteristic;
c) addition of requirements in respect of DC;
d) introduction of the concept of class I and class II assemblies regarding protection against
electric shock.
The text of this International Standard is based on the following documents:
FDIS Report on voting
121B/99/FDIS 121B/103/RVD
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
The reader’s attention is drawn to the fact that Annex N lists all the “in-some-countries”
clauses on differing practices of a less permanent nature regarding this document.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
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 "http://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 publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
The contents of the corrigendum of December 2021 have been included in this copy.
The contents of the corrigendum 2 of September 2023 only applies to the French version.

– 10 – IEC 61439-1:2020 RLV © IEC 2020
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
(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 may 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 new re-structured IEC 61439 series, the following parts are envisaged published:
a) IEC 61439-1: General rules
b) IEC 61439-2: Power switchgear and controlgear assemblies (PSC-assemblies)
c) IEC 61439-3: Distribution boards (to supersede IEC 60439-3) intended to be operated by
ordinary persons (DBO)
d) IEC 61439-4: ASSEMBLIES for construction sites (to supersede IEC 60439-4) Particular
requirements for assemblies for construction sites (ACS)
e) IEC 61439-5: Assemblies for power distribution (to supersede IEC 60439-5) in public
networks
f) IEC 61439-6: Busbar trunking systems (to supersede IEC 60439-2) (busways)
f) IEC 61439-7: Assemblies for specific applications such as marinas, camping sites, market
squares, electric vehicle charging stations
g) IEC TR 61439-0: Guidance to specifying assemblies.
This list is not exhaustive; additional parts may can be developed as the need arises.
___________
IEC 61439-2 includes requirements for assemblies for use in photovoltaic installations.

LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR ASSEMBLIES –

Part 1: General rules
1 Scope
NOTE 1 Throughout this standard, the term ASSEMBLY (see 3.1.1) is used for a low-voltage switchgear and
controlgear assembly.
This part of IEC 61439 lays down the general definitions and states the service conditions,
construction requirements, technical characteristics and verification requirements for low-
voltage switchgear and controlgear assemblies.
This standard cannot be used alone to specify an ASSEMBLY or used for a purpose of
determining conformity. ASSEMBLIES shall comply with the relevant part of the IEC 61439
series; Parts 2 onwards.
NOTE Throughout this document, the term assembly(s) (see 3.1.1) is used for a low-voltage switchgear and
controlgear assembly(s).
For the purpose of determining assembly conformity, the requirements of the relevant part of
the IEC 61439 series, Part 2 onwards, apply together with the cited requirements of this
document. For assemblies not covered by Part 3 onward, Part 2 applies.
This document applies to low-voltage switchgear and controlgear assemblies (ASSEMBLIES)
only when required by the relevant assembly standard 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 designed for a nominal frequency of the incoming supply or supplies not
exceeding 1 000 Hz;
– assemblies intended for indoor and outdoor applications;
– stationary or movable assemblies with or without an enclosure;
– assemblies intended for use in connection with the generation, transmission, distribution
and conversion of electric energy, and for the control of electrical energy consuming
equipment.
– ASSEMBLIES designed for use under special service conditions, for example in ships
and in rail vehicles provided that the other relevant specific requirements are complied
with;
NOTE 2 Supplementary requirements for ASSEMBLIES in ships are covered by IEC 60092-302.
– ASSEMBLIES designed for electrical equipment of machines provided that the other
relevant specific requirements are complied with.
NOTE 3 Supplementary requirements for ASSEMBLIES forming part of a machine are covered by the
IEC 60204 series.
This standard applies to all ASSEMBLIES whether they are designed, manufactured and verified
on a one-off basis or fully standardised and manufactured in quantity.
The manufacture and/or assembly may be carried out other than by the original manufacturer
(see 3.10.1).
This document does not apply to individual devices and self-contained components such as
motor starters, fuse switches, power electronic converter systems and equipment (PECS),
switch mode power supplies (SMPS), uninterruptable power supplies (UPS), basic drive

– 12 – IEC 61439-1:2020 RLV © IEC 2020
modules (BDM), complete drive modules (CDM), adjustable speed power drives systems
(PDS), and other electronic equipment, etc. which will comply with their relevant product
standards. This document describes the integration of devices and self-contained components
into an assembly or into an empty enclosure forming an assembly.
For some applications involving, for example, explosive atmospheres, functional safety, there
can be a need to comply with the requirements of other standards or legislation in addition to
those specified in the IEC 61439 series.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements of this document. For dated references, only the edition
cited applies. For undate
...