IEC 61439-3:2024

Low-voltage switchgear and controlgear assemblies - Part 3: Distribution boards intended to be operated by ordinary persons (DBO)

IEC 61439-3:2024 defines the specific requirements for distribution boards intended to be operated by ordinary persons (abbreviated DBO throughout this document, see 3.1.101) as follows:
- assemblies intended to be operated by ordinary persons (e.g. switching operations and replacing fuse-links), e.g. in domestic (household) applications;
- assemblies containing outgoing circuits with protective devices intended to be operated by ordinary persons, complying e.g. with IEC 60898-1, the IEC 61008 series, the IEC 61009 series, IEC 62606, IEC 62423 and IEC 60269-3;
- assemblies for applications where the nominal voltage to earth does not exceed 300 V AC (see Table G.1 of IEC 61439-1:2020);
NOTE The voltage limits for DC applications are under consideration.
- assemblies with a rated current (Inc) of the outgoing circuits not exceeding 125 A and a rated current (InA) not exceeding 250 A;
- assemblies intended for use in connection with the generation, transmission, distribution and conversion of electrical energy, and for the control of equipment consuming electrical energy and for associated data processing;
- enclosed, stationary assemblies;
- assemblies for indoor or outdoor use.
This second edition 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 the structure of IEC 61439-1:2020;
b) inclusion in the scope of more examples of the type of protection and control devices;
c) deletion of type A and Type B DBOs;
d) addition of a new Annex BB related to DBOs used in a prosumer’s electrical installation (PEI);
e) addition of a new Annex CC related to rated current of a DBO with additional source of supply in parallel/simultaneously with another source that is connected to the DBO e.g. PV.

Ensembles d'appareillage à basse tension - Partie 3: Tableaux de répartition destinés à être utilisés par des personnes ordinaires (DBO)

L'IEC 61439-3:2024 définit les exigences spécifiques pour les tableaux de répartition destinés à être utilisés par des personnes ordinaires (abrégés DBO dans l'ensemble du présent document, voir 3.1.101) ci-après:
- ensembles destinés à être utilisés par des personnes ordinaires (par exemple, pour manœuvrer des appareils de commande et remplacer des éléments de fusible), par exemple dans des applications domestiques;
- ensembles qui contiennent des circuits de départ avec des dispositifs de protection, destinés à être utilisés par des personnes ordinaires, qui satisfont par exemple à l'IEC 60898-1, à la série IEC 61008, à la série IEC 61009, à l'IEC 62606, à l'IEC 62423 et à l'IEC 60269-3;
- ensembles destinés à des applications pour lesquelles la tension nominale à la terre ne dépasse pas 300 V en courant alternatif (voir Tableau G.1 de l'IEC 61439-1:2020);
NOTE Les limites de tension pour les applications en courant continu sont à l'étude.
- ensembles dans lesquels le courant assigné (Inc) des circuits de départ est inférieur ou égal à 125 A et dont le courant assigné (InA) est inférieur ou égal à 250 A;
- ensembles destinés à être utilisés avec des équipements conçus pour la production, le transport, la distribution et la conversion de l'énergie électrique, la commande des matériels qui consomment de l'énergie électrique et le traitement des données associées;
- ensembles fixes sous enveloppe;
- ensembles pour utilisation en intérieure ou en extérieur.
Cette seconde édition annule et remplace la première édition parue en 2012. Cette édition constitue une révision technique.
Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
a) alignement sur la structure de l'IEC 61439-1:2020;
b) inclusion dans le domaine d'application de plus d'exemples de types de dispositifs de protection et de commande;
c) suppression des DBO de type A et de type B;
d) ajout d'une nouvelle Annexe BB relative aux DBO utilisés dans une installation électrique de prosommateur (PEI);
e) ajout d'une nouvelle Annexe CC relative au courant assigné d'un DBO avec une source d'alimentation supplémentaire parallèlement/simultanément avec une autre source reliée au DBO, par exemple un panneau photovoltaïque (PV).

General Information

• Status: Published
• Publication Date: 25-Mar-2024
• ICS: 29.130.20 - Low voltage switchgear and controlgear
• Technical Committee: SC 121B - Low-voltage switchgear and controlgear assemblies
• Drafting Committee: MT 4 - TC 121/SC 121B/MT 4
• Current Stage: PPUB - Publication issued
• Start Date: 22-Mar-2024
• Completion Date: 26-Mar-2024

Relations

• Revises: IEC 61439-3:2012/COR2:2019 - Corrigendum 2 - Low-voltage switchgear and controlgear assemblies - Part 3: Distribution boards intended to be operated by ordinary persons (DBO)
• Effective Date: 05-Sep-2023
• Revises: IEC 61439-3:2012/COR1:2013 - Corrigendum 1 - Low-voltage switchgear and controlgear assemblies - Part 3: Distribution boards intended to be operated by ordinary persons (DBO)
• Effective Date: 05-Sep-2023
• Revises: IEC 61439-3:2012 - Low-voltage switchgear and controlgear assemblies - Part 3: Distribution boards intended to be operated by ordinary persons (DBO)
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 61439-3 ®
Edition 2.0 2024-03
COMMENTED VERSION
INTERNATIONAL
STANDARD
colour
inside
Low-voltage switchgear and controlgear assemblies –
Part 3: Distribution boards intended to be operated by ordinary persons (DBO)
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
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IEC 61439-3 ®
Edition 2.0 2024-03
COMMENTED VERSION
INTERNATIONAL
STANDARD
colour
inside
Low-voltage switchgear and controlgear assemblies –
Part 3: Distribution boards intended to be operated by ordinary persons (DBO)
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.130.20 ISBN 978-2-8322-8659-3
– 2 – IEC 61439-3:2024 CMV © IEC 2024
CONTENTS
FOREWORD .3
1 Scope .6
2 Normative references .7
3 Terms and definitions .7
4 Symbols and abbreviations .8
5 Interface characteristics .8
6 Information .9
7 Service conditions . 10
8 Constructional requirements . 10
9 Performance requirements . 12
10 Design verification . 12
11 Routine verification . 18
Annexes . 21
Annex AA (informative) Items subject to agreement between the assembly DBO
manufacturer and the user . 22
Annex BB (informative) Effects upon a DBO design and related ratings, instructions,
etc. when used in a prosumer’s electrical installation (PEI) . 27
Annex CC (informative) Rated current of an assembly (I ) . 28
nA
Annex DD (informative) List of notes concerning certain countries . 30
Bibliography . 44
List of comments . 45

Figure CC.1 – Example of overloading where I + I is greater than I . 29
n gen(s) nA
Figure DD.1 – Example of temperature rise verification by test of a complete split‑load
DBO as in 10.10.2.3.6 . 36
Figure DD.2 – Calibration of the test circuit . 40
Figure DD.3 – Test circuit to prove coordination of characteristics . 43

Table 101 – Values of assumed loading . 19
Table 102 – Tightening torque values for the verification of mechanical strength . 19
Table AA.1 – Items subject to agreement between the ASSEMBLY DBO manufacturer
and the user. 22
Table DD.1 – Requirements for final circuit protective devices: Circuit-breakers
complying with BS EN 60898 and RCBOs complying with BS EN 61009. 37
Table DD.2 – Requirements for final circuit protective devices: Semi-enclosed fuses
complying with BS 3036 and cartridge fuses complying with BS 88.3 . 38
Table DD.3 – Cross-sections of copper conductors on load side of protective device
under test . 38
Table DD.4 – Preparation for Test B . 41

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR ASSEMBLIES –

Part 3: Distribution boards intended to be operated
by ordinary persons (DBO)
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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This commented version (CMV) of the official standard IEC 61439-3:2024 edition 2.0
allows the user to identify the changes made to the previous IEC 61439-3:2012
edition 1.0. Furthermore, comments from IEC TC SC 121B experts are provided to explain
the reasons of the most relevant changes, or to clarify any part of the content.
A vertical bar appears in the margin wherever a change has been made. Additions are in
green text, deletions are in strikethrough red text. Experts' comments are identified by a
blue-background number. Mouse over a number to display a pop-up note with the
comment.
This publication contains the CMV and the official standard. The full list of comments is
available at the end of the CMV.

– 4 – IEC 61439-3:2024 CMV © IEC 2024
IEC 61439-3 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 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 the structure of IEC 61439-1:2020;
b) inclusion in the scope of more examples of the type of protection and control devices;
c) deletion of type A and type B DBOs;
d) addition of a new Annex BB related to DBOs used in a prosumer’s electrical installation
(PEI);
e) addition of a new Annex CC related to rated current of a DBO with additional source of
supply in parallel/simultaneously with another source that is connected to the DBO e.g. PV.
The text of this International Standard is based on the following documents:
Draft Report on voting
121B/193/FDIS 121B/195/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 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.
The reader’s attention is drawn to the fact that Annex DD 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 in the IEC 61439 series, published under the general title Low-voltage
switchgear and controlgear assemblies, can be found on the IEC website.
...

IEC 61439-3 ®
Edition 2.0 2024-03
EXTENDED VERSION
INTERNATIONAL
STANDARD
colour
inside
This extended version of IEC 61439-3:2024 includes the content of the references made to
IEC 61439-1:2020
Low-voltage switchgear and controlgear assemblies –
Part 3: Distribution boards intended to be operated by ordinary persons (DBO)
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.

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About the IEC
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International Standards for all electrical, electronic and related technologies.

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IEC 61439-3 ®
Edition 2.0 2024-03
EXTENDED VERSION
INTERNATIONAL
STANDARD
colour
inside
This extended version of IEC 61439-3:2024 includes the content of the references made to
IEC 61439-1:2020
Low-voltage switchgear and controlgear assemblies –
Part 3: Distribution boards intended to be operated by ordinary persons (DBO)
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.130.20 ISBN 978-2-8322-8671-5

– 2 – IEC 61439-3:2024 EXV © IEC 2024

CONTENTS
FOREWORD . 9
1 Scope . 12
2 Normative references . 12
3 Terms and definitions . 16
3.1 General terms . 16
3.2 Constructional units of assemblies . 19
3.3 External design of assemblies . 20
3.4 Structural parts of assemblies . 21
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 . 34
4 Symbols and abbreviations . 34
5 Interface characteristics . 35
5.1 General . 35
5.2 Voltage ratings . 36
5.2.1 Rated voltage (U ) (of the assembly) . 36
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 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 . 39
6.1 Assembly designation marking . 39
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
7.1.2 Pollution degree . 41
7.2 Special service conditions . 42
7.3 Conditions during transport, storage and installation . 42
8 Constructional requirements . 43

8.1 Strength of materials and parts . 43
8.1.1 General . 43
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. 46
8.3.1 General . 46
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 . 53
8.5.1 Fixed parts . 53
8.5.2 Removable parts . 53
8.5.3 Selection of switching devices and components . 54
8.5.4 Installation of switching devices and components . 54
8.5.5 Accessibility . 55
8.5.6 Barriers . 55
8.5.7 Direction of operation and indication of switching positions . 55
8.5.8 Indicator lights and push-buttons . 55
8.5.9 Power factor correction banks . 55
8.6 Internal electrical circuits and connections . 56
8.6.1 Main circuits . 56
8.6.2 Auxiliary circuits . 56
8.6.3 Bare and insulated conductors . 57
8.6.4 Selection and installation of non-protected live conductors to reduce the
possibility of short-circuits . 58
8.6.5 Identification of the conductors of main and auxiliary circuits . 58
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 . 58
8.6.7 Conductors in AC circuits passing through ferromagnetic enclosures or
plates . 58
8.7 Cooling . 58
8.8 Terminals for external cables . 58
9 Performance requirements . 60
9.1 Dielectric properties . 60
9.1.1 General . 60

– 4 – IEC 61439-3:2024 EXV © IEC 2024

9.1.2 Power-frequency withstand voltage .
...

IEC 61439-3 ®
Edition 2.0 2024-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Low-voltage switchgear and controlgear assemblies –
Part 3: Distribution boards intended to be operated by ordinary persons (DBO)

Ensembles d'appareillage à basse tension –
Partie 3: Tableaux de répartition destinés à être utilisés par des personnes
ordinaires (DBO)
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
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International Standards for all electrical, electronic and related technologies.

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IEC 61439-3 ®
Edition 2.0 2024-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Low-voltage switchgear and controlgear assemblies –

Part 3: Distribution boards intended to be operated by ordinary persons (DBO)

Ensembles d'appareillage à basse tension –

Partie 3: Tableaux de répartition destinés à être utilisés par des personnes

ordinaires (DBO)
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.130.20  ISBN 978-2-8322-8364-6

– 2 – IEC 61439-3:2024 © IEC 2024
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 6
4 Symbols and abbreviations . 7
5 Interface characteristics. 7
6 Information . 8
7 Service conditions . 9
8 Constructional requirements . 9
9 Performance requirements. 11
10 Design verification . 11
11 Routine verification . 15
Annexes . 18
Annex AA (informative) Items subject to agreement between the DBO manufacturer
and the user . 19
Annex BB (informative) Effects upon a DBO design and related ratings, instructions,
etc. when used in a prosumer’s electrical installation (PEI) . 23
Annex CC (informative) Rated current of an assembly (I ) . 24
nA
Annex DD (informative) List of notes concerning certain countries . 26
Bibliography . 40

Figure CC.1 – Example of overloading where I + I is greater than I . 25
n gen(s) nA
Figure DD.1 – Example of temperature rise verification by test of a complete split‑load
DBO as in 10.10.2.3.6 . 32
Figure DD.2 – Calibration of the test circuit . 36
Figure DD.3 – Test circuit to prove coordination of characteristics . 39

Table 101 – Values of assumed loading . 16
Table 102 – Tightening torque values for the verification of mechanical strength . 17
Table AA.1 – Items subject to agreement between the DBO manufacturer and the user . 19
Table DD.1 – Requirements for final circuit protective devices: Circuit-breakers
complying with BS EN 60898 and RCBOs complying with BS EN 61009 . 33
Table DD.2 – Requirements for final circuit protective devices: Semi-enclosed fuses

complying with BS 3036 and cartridge fuses complying with BS 88.3 . 34
Table DD.3 – Cross-sections of copper conductors on load side of protective device
under test . 34
Table DD.4 – Preparation for Test B . 37

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR ASSEMBLIES –

Part 3: Distribution boards intended to be operated
by ordinary persons (DBO)
FOREWORD
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IEC 61439-3 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 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 the structure of IEC 61439-1:2020;
b) inclusion in the scope of more examples of the type of protection and control devices;
...