EN IEC 61439-4:2026

• Abstract:

  NOTE Throughout this standard, 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 part of 61439 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; - transportable (semi-fixed) or mobile ASSEMBLIES with enclosure. The manufacture and/or assembly may be carried out other than by the original manufacturer. This standard 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 standard does not apply to ASSEMBLIES for use in the administrative centres of construction sites (offices, cloakrooms, ASSEMBLY rooms, canteens, restaurants, dormitories, toilets, etc.). Requirements for electrical protection provided by equipment manufactured according to this International Standard are given in IEC 60364-7-704.

• Status: Published
• Publication Date: 29-Oct-2026
• ICS: 29.130.20 - Low voltage switchgear and controlgear
• Technical Committee: CLC/SR 121B - Low-voltage switchgear and controlgear assemblies
• Drafting Committee: IEC/SC 121B - Low-voltage switchgear and controlgear assemblies
• Current Stage: 6060 - Document made available - Publishing
• Start Date: 30-Oct-2026
• Due Date: 31-Mar-2023
• Completion Date: 30-Oct-2026
• Directive: 2014/30/EU - Directive 2014/30/EU of the European Parliament and of the Council of 26 February 2014 on the harmonisation of the laws of the Member States relating to electromagnetic compatibility (recast)
• Directive:

  ---

  2014/35/EU - Directive 2014/35/EU of the European Parliament and of the Council of 26 February 2014 on the harmonisation of the laws of the Member States relating to the making available on the market of electrical equipment designed for use within certain voltage limits
• Mandate: M/511 - Mandate to CEN, CENELEC and ETSI relating to harmonised standards in the field of the Low Voltage Directive
• Ref Project: SIST EN IEC 61439-4:2026 - Low-voltage switchgear and controlgear assemblies - Part 4: Particular requirements for assemblies for construction sites (ACS) (IEC 61439-4:2023)

• Replaces: EN 61439-4:2013 - Low-voltage switchgear and controlgear assemblies - Part 4: Particular requirements for assemblies for construction sites (ACS)
• Effective Date: 26-Jul-2021
• Refers: EN 60068-2-42:2003 - Environmental testing - Part 2-42: Tests - Test Kc: Sulphur dioxide test for contacts and connections
• Effective Date: 13-Oct-2026
• Refers: EN IEC 61558-2-23:2025 - 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
• Effective Date: 13-Oct-2026
• Refers: EN 60068-2-27:2009 - Environmental testing - Part 2-27: Tests - Test Ea and guidance: Shock
• Effective Date: 13-Oct-2026
• Referred By: HD 60364-7-712:2016 - Low-voltage electrical installations - Part 7-712: Requirements for special installations or locations - Photovoltaic (PV) systems
• Effective Date: 03-Nov-2026
• Referred By: EN IEC 60947-4-1:2025 - Low-voltage switchgear and controlgear - Part 4-1: Contactors and motor-starters - Electromechanical contactors and motor-starters
• Effective Date: 03-Nov-2026
• Referred By: EN IEC 60947-9-1:2019 - Low-voltage switchgear and controlgear - Part 9-1: Active arc-fault mitigation systems - Arc quenching devices
• Effective Date: 03-Nov-2026
• Referred By: EN IEC 61400-1:2019 - Wind energy generation systems - Part 1: Design requirements
• Effective Date: 03-Nov-2026
• Referred By: EN IEC 60947-1:2021 - Low-voltage switchgear and controlgear - Part 1: General rules
• Effective Date: 03-Nov-2026
• Referred By: EN 12111:2002+A1:2009 - Tunnelling machines - Road headers, continuous miners and impact rippers - Safety requirements
• Effective Date: 03-Nov-2026
• Referred By: HD 60364-7-710:2025 - Low-voltage electrical installations - Part 7-710: Requirements for special installations or locations - Medical locations
• Effective Date: 03-Nov-2026
• Referred By: EN IEC 60947-4-1:2019 - Low-voltage switchgear and controlgear - Part 4-1: Contactors and motor-starters - Electromechanical contactors and motor-starters
• Effective Date: 03-Nov-2026
• Referred By: EN IEC 62271-202:2022 - High-voltage switchgear and controlgear - Part 202: AC prefabricated substations for rated voltages above 1 kV and up to and including 52 kV
• Effective Date: 03-Nov-2026
• Referred By: EN IEC 62271-212:2022 - High-voltage switchgear and controlgear - Part 212: Compact Equipment Assembly for Distribution Substation (CEADS) for AC voltages up to 52 kV
• Effective Date: 03-Nov-2026
• Referred By: EN 50600-2-2:2014 - Information technology - Data centre facilities and infrastructures - Part 2-2: Power distribution
• Effective Date: 03-Nov-2026

EN IEC 61439-4:2026 is the CLC/CENELEC standard for low-voltage switchgear and controlgear assemblies for construction sites (ACS). It specifies the particular requirements for ACS used on indoor and outdoor construction and similar sites, including transportable (semi-fixed) and mobile enclosed assemblies. Manufacturers, assemblers, designers, and users use it to define ratings, construction, documentation, and verification for these assemblies.

What does EN IEC 61439-4:2026 specify?

EN IEC 61439-4:2026 covers ACS with rated voltage up to 1 000 V AC or 1 500 V DC, including assemblies with incorporated transformers whose primary and secondary voltages stay within those limits. It applies to construction-site use, not to administrative centres on a site, and it excludes individual devices and self-contained components that are covered by their own product standards.

The standard is organized into Clauses 1 to 11, with Clause 101 adding ACS-specific features. It is read together with IEC 61439-1, so the general rules in Part 1 apply unless this part modifies or replaces them.

Annex	What it covers
C	User information template and items to agree between the manufacturer and the user
D	Design verification list and the verification method for each characteristic
L	Guidance on temperature-rise verification
M	Verification of short-circuit withstand strength of busbar structures by comparison with a tested reference design by calculation; this part states that the Part 1 annex is not applicable here
N	Notes on certain country practices
AA	Void

What are the key requirements of EN IEC 61439-4:2026?

EN IEC 61439-4:2026 focuses on the ratings, enclosure, protection, and verification needed for site use. In practice, it tells the manufacturer what to declare, how to build the ACS, and what to prove by test or assessment before the assembly is supplied.

Ratings, declared characteristics, and marking

Clause 5.3.1 ties the ACS rated current to the incoming circuit, so the incoming side must carry the declared current without exceeding the temperature-rise limits of Part 1. Clause 5.4 requires the manufacturer to declare the rated diversity factor (RDF) or use the table values, which matters when the outgoing circuits are not expected to run at full load all at once.

Clause 5.6 requires the manufacturer to declare the function(s), external design, mobility, degree of protection, mounting method, protection against electric shock, corrosion resistance, special service conditions, and EMC classification. Clause 6 then requires durable marking on the ACS and supporting technical documentation. For a buyer or site designer, this is the basic information needed to match the assembly to the job, the network, and the site conditions.

Clause 6.2.2 also expects the documentation to state which other assemblies may be connected, and whether the compatibility depends on the earthing system or on co-ordination of protective devices. That helps avoid mismatched equipment in a chain of site distribution assemblies.

Service conditions and construction

Clause 7 limits the normal pollution degree to 3 or 4. A microenvironment may be reduced to pollution degree 2 only if the enclosure is at least IP5X and condensation is avoided. Clause 7 also adds heavily polluted atmosphere as a special service condition, which matters for outdoor and industrial construction sites.

Clause 8 places all apparatus inside the enclosure, except for the items allowed by 8.101, and requires protection against corrosion, ultraviolet radiation for insulating external parts, lifting provision, and mechanical strength. It also requires the ACS to withstand the site-related shock and impact conditions defined in the clause. In practice, this is what drives the choice of enclosure material, coating, handles, feet, and wall-fixing arrangements.

Clause 8.2.2 sets the minimum degree of protection at IP44 for the ACS with doors closed and removable parts fitted. It also sets minimum protection for operating faces, doors, and socket-outlets, and requires the declared IP rating to match verified test results. Clause 8.5.3 prevents plugs with different current or voltage ratings from being interchangeable, and requires three-phase connections to keep the same phase order. Clause 8.5.101 limits freely accessible parts to socket-outlets, operating handles, and control buttons, while the main switch actuator must be easily accessible.

Clause 8.8 requires external cable connections to be re-wireable or socket-outlets, and the socket-outlets must have at least 16 A rating. Clause 8.101 requires supports or a wall-fixing system, and Clause 8.102 places the cable outlet high enough for the bending radius of the largest connected cable. These points are practical site-use rules: the ACS must stand safely, be easy to connect, and avoid cable damage.

ACS functional arrangement

Clause 101 defines the ACS as one incoming unit with one or more outgoing units, and it may also include metering units and transformer units. The incoming unit needs a means of isolation and overcurrent protection, plus a way to secure the isolating device in the open position. If upstream protection is used instead, the manufacturer has to give the user the information needed to select it correctly.

Metering units intended for billing purposes need agreement with the energy supplier. Transformer units may be LV/ELV or LV/LV, and the transformers are required to follow IEC 61558-2-23. Outgoing units must provide isolation, load switching, overcurrent protection, and fault protection, and socket-outlet circuits need protection against electric shock and overcurrent. Table 101 gives assumed loading factors for groups of outgoing circuits, which helps the manufacturer declare realistic loading for site distribution.

Design verification and routine checks

Clause 10 and Annex D organize the design verification of the ACS. Table D.1 shows which characteristics are verified by testing, comparison with a reference design, or assessment. The standard includes corrosion testing for heavily polluted atmosphere, mechanical impact and shock testing, verification of enclosure protection, dielectric tests, temperature-rise checks, short-circuit withstand verification, EMC, and mechanical operation.

Where an empty IEC 62208 enclosure is used without performance-degrading changes, the enclosure tests do not need to be repeated except for mechanical strength, unless the ACS is declared for heavily polluted atmosphere. Clause 11 covers routine verification, so each manufactured ACS still needs the checks required before delivery.

What terms does EN IEC 61439-4:2026 define?

EN IEC 61439-4:2026 defines ACS as a low-voltage switchgear and controlgear assembly for construction sites, with the internal electrical and mechanical connections needed for site use indoors and outdoors.

A metering unit is a functional unit equipped with apparatus for metering electrical energy. It is the part used when site energy consumption has to be measured.

A transformer unit is a functional unit consisting mainly of one or more transformers. The standard uses this for ACS that need LV/ELV or LV/LV conversion.

An enclosed ACS is enclosed on all sides, except possibly the mounting surface, so that it provides a defined degree of protection. This is the normal form for site use.

A box-type ACS is an enclosed ACS intended either for mounting on a vertical surface or for standing on a horizontal surface with feet, legs, or a separate mounting arrangement. This affects installation and handling on site.

A transportable ACS is a semi-fixed ACS that is not permanently fixed and may be moved on the same site after disconnection from the supply. A mobile ACS can be moved as work advances without being disconnected from the supply.

The rated diversity factor (RDF) is the declared assumed loading of outgoing circuits or groups of outgoing circuits. It matters because it is part of the current-sizing and load-assumption basis for the assembly.

Who uses EN IEC 61439-4:2026?

EN IEC 61439-4:2026 is used by ACS manufacturers, panel builders, and assemblers who design and build site distribution assemblies. It is also used by electrical designers, temporary power contractors, construction-site operators, energy suppliers involved with metering units, test laboratories, and quality or procurement teams that need to check ratings, protection, IP level, and documentation.

What changed in EN IEC 61439-4:2026 from the previous edition?

The text states that this edition cancels and replaces IEC 60439-4:2004 and is a technical revision. The significant changes listed are:

• the title was changed to “Part 4: Particular requirements for assemblies for construction sites (ACS)”
• the structure and technical content were aligned with IEC 61439-1 where applicable
• the standard was adapted to allow comparison with tested ACS

Which standards are used with EN IEC 61439-4:2026?

Standard	What it contributes
IEC 61439-1	General rules for low-voltage switchgear and controlgear assemblies
IEC 60364-7-704	Installation requirements for construction and demolition site installations
IEC 61140	Common aspects of protection against electric shock
IEC 60068-2-27	Shock test used for mechanical impact and shock verification
IEC 60068-2-42	Sulphur dioxide corrosion test for heavily polluted atmosphere
IEC 61558-2-23	Requirements and tests for transformers and power supply units for construction sites

What does the EN IEC 61439-4:2026 document contain?

EN IEC 61439-4:2026 contains the declaration information, construction rules, service-condition limits, and verification methods needed for ACS. It includes a user information template in Annex C, a design-verification list in Annex D, a table of assumed loading values, and a test figure for impact verification.

The document also gives the ACS-specific functional structure in Clause 101, covering incoming units, outgoing units, metering units, and transformer units. For design and test work, it provides the practical checks for marking, IP rating, corrosion, mechanical strength, short-circuit withstand, EMC, and routine verification.

SLOVENSKI STANDARD
01-december-2026
Nadomešča:
SIST EN 61439-4:2013
Sestavi nizkonapetostnih stikalnih in krmilnih naprav - 4. del: Posebne zahteve za
sestave na gradbiščih (ACS) (IEC 61439-4:2023)
Low-voltage switchgear and controlgear assemblies - Part 4: Particular requirements for
assemblies for construction sites (ACS) (IEC 61439-4:2023)
Niederspannungs-Schaltgerätekombinationen - Teil 4: Besondere Anforderungen für
Baustromverteiler (BV) (IEC 61439-4:2023)
Ensembles d'appareillage à basse tension - Partie 4: Exigences particulières pour
ensembles de chantiers (EC) (IEC 61439-4:2023)
Ta slovenski standard je istoveten z: EN IEC 61439-4:2026
ICS:
29.130.20 Nizkonapetostne stikalne in Low voltage switchgear and
krmilne naprave controlgear
91.200 Gradbena tehnologija Construction technology
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN IEC 61439-4

NORME EUROPÉENNE
EUROPÄISCHE NORM October 2026
ICS 29.130.20 Supersedes EN 61439-4:2013
English Version
Low-voltage switchgear and controlgear assemblies - Part 4:
Particular requirements for assemblies for construction sites
(ACS)
(IEC 61439-4:2023)
Ensembles d'appareillage à basse tension - Partie 4 : Niederspannungs-Schaltgerätekombinationen - Teil 4:
Exigences particulières pour ensembles de chantiers (EC) Besondere Anforderungen für Baustromverteiler (BV)
(IEC 61439-4:2023) (IEC 61439-4:2023)
This European Standard was approved by CENELEC on 2024-10-16. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Türkiye and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 61439-4:2026 E

European foreword
The text of document 121B/183/FDIS, future edition 2 of IEC 61439-4, prepared by SC 121B "Low-
voltage switchgear and controlgear assemblies" of IEC/TC 121 "Switchgear and controlgear and their
assemblies for low voltage" was submitted to the IEC-CENELEC parallel vote and approved by
CENELEC as EN IEC 61439-4:2026.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2027-10-31
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2029-10-31
document have to be withdrawn
This document supersedes EN 61439-4:2013 and all of its amendments and corrigenda (if any).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
This document is read in conjunction with EN IEC 61439-1:2021 .
Any feedback and questions on this document should be directed to the users’ national committee. A
complete listing of these bodies can be found on the CENELEC website.
Endorsement notice
The text of the International Standard IEC 61439-4:2023 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standard indicated:
IEC 60309-1 NOTE Approved as EN IEC 60309-1
IEC 60309-2 NOTE Approved as EN IEC 60309-2
IEC 60364 series NOTE Approved as HD 60364 series

As impacted by EN IEC 61439-1:2021/AC:2022-01 and EN IEC 61439-1:2021/AC:2023-11.
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
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
undated references, the latest edition of the referenced document (including any amendments)
applies.
NOTE 1  Where an International Publication has been modified by common modifications, indicated by (mod),
the relevant EN/HD applies.
NOTE 2  Up-to-date information on the latest versions of the European Standards listed in this annex is available
here: www.cencenelec.eu.
Annex ZA of EN IEC 61439-1:2021 applies, except as follows:
Publication Year Title EN/HD Year
IEC 60068-2-27 - Environmental testing - Part 2-27: Tests - EN 60068-2-27 -
Test Ea and guidance: Shock
IEC 60068-2-42 - Environmental testing - Part 2-42: Tests - EN 60068-2-42 -
Test Kc: Sulphur dioxide test for contacts
and connections
IEC 60364-7-704 2017 Low-voltage electrical installations - Part 7- HD 60364-7-704 2018
(mod) 704: Requirements for special installations
or locations - Construction and demolition
site installations
IEC 61439-1 2020 Low-voltage switchgear and controlgear EN IEC 61439-1 2021
assemblies - Part 1: General rules
IEC 61558-2-23 - Safety of transformers, reactors, power EN IEC 61558-2-23 -
supply units and combinations thereof -
Part 2-23: Particular requirements and
tests for transformers and power supply
units for construction sites
As impacted by EN IEC 61439-1:2021/AC:2022-01 and EN IEC 61439-1:2021/AC:2023-11.
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

IEC 61439-4:2023 © IEC 2023 – 3 –
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
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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) 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
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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.
IEC 61439-4:2023 © IEC 2023 – 5 –
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

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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)

IEC 61439-4:2023 © IEC 2023 – 7 –
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

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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).

IEC 61439-4:2023 © IEC 2023 – 9 –
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);
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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.

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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 shap
...