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

IEC 61439-3:2012 defines the specific requirements for distribution boards intended to be operated by ordinary persons (DBO). DBOs have the following criteria:
- intended to be operated by ordinary persons (e.g. switching operations and replacing fuse-links), e.g. in domestic (household) applications;
- outgoing circuits contain protective devices, intended to be operated by ordinary persons, complying e.g. with IEC 60898-1, IEC 61008, IEC 61009, IEC 62423 and IEC 60269-3;
- rated voltage to earth does not exceed 300 V a.c.;
- rated current (Inc) of the outgoing circuits does not exceed 125 A and the rated current (InA) of the DBO does not exceed 250 A;
- intended for the distribution of electrical energy;
- enclosed, stationary;
- for indoor or outdoor use.
This first edition cancels and replaces the first edition of IEC 60439-3 (1990), Amendment 1 (1993) and Amendment 2 (2001). It constitutes a technical revision. This edition includes the following significant technical changes with respect to IEC 60439-3 (including the amendments):
- alignment with IEC 61439-1:2011.
This publication is to be read in conjunction with IEC 61439-1:2011. The contents of the corrigenda of September 2013 and March 2019 have been included in this copy.

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

La CEI 61439-3:2012 définit les exigences spécifiques applicables aux tableaux de répartition destinés à être utilisés par des personnes ordinaires (DBO). Les DBO satisfont les critères suivants:
- destinés à être utilisés par des personnes ordinaires (par exemple, pour man uvrer des appareils de commande et remplacer des éléments de fusible), par exemple dans des applications domestiques;
- les circuits de départ contiennent des dispositifs de protection, destinés à être utilisés par des personnes ordinaires, satisfaisant par exemple à la CEI 60898-1, la CEI 61008, la CEI 61009, la CEI 62423 et la CEI 60269-3;
- la tension assignée par rapport à la terre ne dépasse pas 300 V en courant alternatif;
- le courant assigné (Inc) des circuits de départ ne dépasse pas 125 A, et le courant assigné (InA) du DBO ne dépasse pas 250 A;
- destinés à la distribution d'énergie électrique;
- sous enveloppe, fixes;
- pour utilisation intérieure ou extérieure.
Cette première édition annule et remplace la première édition de la CEI 60439-3 (1990), l'Amendement 1 (1993) et l'Amendement 2 (2001). Elle constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à la CEI 60439-3 (y compris les amendements):
- alignement avec la CEI 61439-1:2011.
Cette publication doit être lue conjointement avec la CEI 61439-1:2011. Le contenu du corrigendum de septembre 2013 et mars 2019 a été pris en considération dans cet exemplaire.

General Information

Status
Published
Publication Date
15-Feb-2012
Current Stage
PPUB - Publication issued
Start Date
16-Feb-2012
Completion Date
16-Feb-2012
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IEC 61439-3
Edition 1.0 2012-02
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)
IEC 61439-3:2012
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC 61439-3
Edition 1.0 2012-02
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
PRICE CODE
INTERNATIONALE
CODE PRIX R
ICS 29.130.20 ISBN 978-2-88912-922-5

Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 3 ----------------------
– 2 – 61439-3 © IEC:2012
CONTENTS

FOREWORD ........................................................................................................................... 3

1 Scope ............................................................................................................................... 5

2 Normative references ....................................................................................................... 5

3 Terms and definitions ....................................................................................................... 6

4 Symbols and abbreviations ............................................................................................... 6

5 Interface characteristics ................................................................................................... 6

6 Information ....................................................................................................................... 7

7 Service conditions ............................................................................................................ 7

8 Constructional requirements ............................................................................................. 8

9 Performance requirements ............................................................................................... 9

10 Design verification ............................................................................................................ 9

11 Routine verification ......................................................................................................... 12

Annexes ............................................................................................................................... 15

Annex AA (informative) Items subject to agreement between the ASSEMBLY

manufacturer and the user .................................................................................................... 16

Bibliography .......................................................................................................................... 20

Figure 101 – Example of temperature rise verification by test of a complete DBO

as in 10.10.2.3.6 .................................................................................................................... 14

Table 101 – Values of assumed loading ................................................................................ 12

Table 102 – Tightening torque values for the verification of mechanical strength .................. 13

Table AA.1 – Items subject to agreement between the ASSEMBLY manufacturer and the

user ...................................................................................................................................... 16

---------------------- Page: 4 ----------------------
61439-3 © IEC:2012 – 3 –
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

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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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

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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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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

indispensable for the correct application of this publication.

9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of

patent rights. IEC shall not be held responsible for identifying any or all such patent rights.

International Standard IEC 61439-3 has been prepared by subcommittee 17D: Low-voltage

switchgear and controlgear assemblies, of IEC technical committee 17: Switchgear and

controlgear.

This first edition cancels and replaces the first edition of IEC 60439-3 (1990), Amendment 1

(1993) and Amendment 2 (2001). It constitutes a technical revision.

This edition includes the following significant technical changes with respect to IEC 60439-3

(including the amendments):
– alignment with IEC 61439-1:2011.
---------------------- Page: 5 ----------------------
– 4 – 61439-3 © IEC:2012
The text of this standard is based on the following documents:
FDIS Report on voting
17D/448/FDIS 17D/450/RVD

Full information on the voting for the approval of this standard can be found in the report on

voting indicated in the above table.

This standard is to be read in conjunction with IEC 61439-1. The provisions of the general

rules dealt with in IEC 61439-1 (hereinafter referred to as Part 1) are applicable to this

standard where they are specifically cited. When this standard states “addition” “modification”

or “replacement”, the relevant text in Part 1 is to be adapted accordingly.

Subclauses that are numbered with a 101 (102, 103, etc.) suffix are additional to the same

subclause in Part 1.
Tables and figures in this Part 3 that are new are numbered starting with 101.
New annexes in this Part 3 are lettered AA, BB, etc.

The “in some countries” notes regarding differing national practices are contained in the

following subclauses:
3.1.102
6.1
8.2.1
8.5.3
8.6.1
8.8

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.

This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

The committee has decided that the contents of this publication will remain unchanged until

the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data

related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.

The contents of the corrigenda of September 2013 and March 2019 have been included in

this copy.
---------------------- Page: 6 ----------------------
61439-3 © IEC:2012 – 5 –
LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR ASSEMBLIES –
Part 3: Distribution boards intended to be operated
by ordinary persons (DBO)
1 Scope

This part of IEC 61439 defines the specific requirements for distribution boards intended to be

operated by ordinary persons (DBO).
DBOs have the following criteria:

– intended to be operated by ordinary persons (e.g. switching operations and replacing

fuse-links), e.g. in domestic (household) applications;

– outgoing circuits contain protective devices, intended to be operated by ordinary

persons, complying e.g. with IEC 60898-1, IEC 61008, IEC 61009, IEC 62423 and
IEC 60269-3;
– rated voltage to earth does not exceed 300 V a.c.;

– rated current (I ) of the outgoing circuits does not exceed 125 A and the rated current

(I ) of the DBO does not exceed 250 A;
– intended for the distribution of electrical energy;
– enclosed, stationary;
– for indoor or outdoor use.

DBOs may also include control and/or signaling devices associated with the distribution of

electrical energy.

This standard applies to all DBOs whether they are designed, manufactured and verified on a

one-off basis or fully standardised and manufactured in quantity.
DBOs may be assembled outside the factory of the original manufacturer.

This standard does not apply to individual devices and self-contained components, such as

circuit breakers, fuse switches, electronic equipment, etc. which will comply with the relevant

product standards.

This standard does not apply to the specific types of ASSEMBLIES covered by other parts of

IEC 61439.
2 Normative references
This clause of Part 1 applies except as follows.
Addition:
IEC 60068-2-75, Environmental testing – Part 2:Tests – Test Eh: Hammer tests

IEC 60269-3, Low-voltage fuses – Part 3: Supplementary requirements for fuses for use by

unskilled persons (fuses mainly for household and similar applications) – Examples of

standardized systems of fuses A to F
---------------------- Page: 7 ----------------------
– 6 – 61439-3 © IEC:2012

IEC 60898-1:2010, Electrical accessories – Circuit-breakers for overcurrent protection for

household and similar installations – Part 1: Circuit-breakers for a.c. operation

IEC 61008 (all parts), Residual current operated circuit-breakers without integral overcurrent

protection for household and similar uses (RCCBs)

IEC 61009 (all parts), Residual current operated circuit-breakers with integral overcurrent

protection for household and similar uses (RCBOs)

IEC 61439-1:2011, Low-voltage switchgear and controlgear assemblies – Part 1: General

rules

IEC 62423:2009, Type F and type B residual current operated circuit-breakers with and

without integral overcurrent protection for household and similar uses
3 Terms and definitions
This clause of Part 1 applies except as follows.
3.1 General terms
Additional terms:
3.1.101
distribution board intended to be operated by ordinary persons
DBO

ASSEMBLY used to distribute electrical energy in domestic (household) applications and other

places where operation is intended by ordinary persons

Note 1 to entry Switching operations and replacing fuse-links are examples of operations intended to be carried

out by normal persons.
3.1.102
type A DBO
DBO designed to accept single pole devices

Note 1 to entry In the UK, a type A DBO used principally for domestic (household) installations and having a

maximum incoming unit rating of 100 A and a maximum outgoing circuit rating of 63 A, is known as a "consumer

unit" or "customer distribution board".
3.1.103
type B DBO
DBO designed to accept multi-pole and/or single pole devices
4 Symbols and abbreviations
This clause of Part 1 applies.
5 Interface characteristics
This clause of Part 1 applies except as follows.
5.1 General
Addition:
---------------------- Page: 8 ----------------------
61439-3 © IEC:2012 – 7 –

This objective can be achieved through one of two typical processes; the user will either

select a catalogue product, the characteristics of which meet the required user needs, or

make a specific agreement with the manufacturer.

In both cases, the specification schedule according to Annex AA is intended to help the user

to provide all data necessary to specify, and to help the manufacturer to characterize the

actual DBO. In some cases information declared by the DBO manufacturer may take the place

of an agreement.
5.2.4 Rated impulse withstand voltage (U ) (of the ASSEMBLY)
imp
Replacement:

The rated impulse withstand voltage shall be equal to or higher than the values stated for the

transient overvoltages occurring in the electrical system(s) to which the circuit is designed to

be connected.

DBO’s shall comply with a minimum overvoltage category III (see IEC 60364-4-44) according

to Table G.1 of Annex G of Part 1.
5.4 Rated diversity factor (RDF)
Addition:

In the absence of an agreement between the DBO manufacturer and user concerning the

actual load currents, the assumed loading of the outgoing circuits of the DBO or group of

outgoing circuits may be based on the values in Table 101.
5.6 Other characteristics
Addition:
q) type A or type B DBO (see 3.1.102 and 3.1.103).
6 Information
This clause of Part 1 applies except as follows.
6.1 ASSEMBLY designation marking
Addition to first paragraph:
The test of 10.2.7 only applies to DBOs intended for outdoor installation.

NOTE In Germany and Sweden, 10.2.7 applies to DBOs intended for indoor installation.

Addition of the following new items:
e) rated current of the DBO using the symbol I e.g. I 250 A;
nA nA
f) degree of protection if greater than IP 2XC.
7 Service conditions
This clause of Part 1 applies except as follows.
---------------------- Page: 9 ----------------------
– 8 – 61439-3 © IEC:2012
7.1.3 Pollution degree
Addition:
A minimum pollution degree 2 applies.
8 Constructional requirements
This clause of Part 1 applies except as follows.
8.2.1 Protection against mechanical impact
Replacement:
The DBO shall comply with the following IK codes according to IEC 62262
– IK 05 for a DBO for indoor use,
– IK 07 for a DBO for outdoor use.
Compliance shall be verified according to 10.2.6.

NOTE In the USA, no IK code is required as the requirements applicable to a “type” designation (see Note 1 in

8.2.2 of IEC 61439-1:2011) cover this consideration.

8.2.2 Protection against contact with live parts, ingress of solid foreign bodies and

water
Replacement of the second paragraph:

The degree of protection of a DBO for indoor installation shall be at least IP 2XC after

installation in accordance with the DBO manufacturer’s instructions.
8.4.6.2.5 Obstacles
This subclause of Part 1 does not apply.
8.5.3 Selection of switching devices and components
Addition:

Outgoing circuits shall contain protective devices, intended to be operated by ordinary

persons, complying e.g. with IEC 60898-1, IEC 61008, IEC 61009, IEC 62423 and
IEC 60269-3.

Re-closing of the incoming protective device when incorporated within the DBO not complying

with the above standards, shall require a key or tool. Alternatively a label stating re-closing of

a tripped device shall only be carried out by an instructed or skilled person shall be located in

the vicinity of the incoming protective device.

Circuit-breakers shall be so designed or installed that it shall not be possible to modify their

settings or calibration without a deliberate act involving the use of a key or tool, and resulting

in a visible indication of their setting or calibration.

When an incoming protective device incorporated within the DBO contains fuses having fuse-

links not complying with IEC 60269-3, a key or tool shall be required for access to replace the

fuse-links.
---------------------- Page: 10 ----------------------
61439-3 © IEC:2012 – 9 –

NOTE In Norway, protective devices in outgoing circuits used for wiring protection in building shall comply with

IEC 60898-1, IEC 61008, IEC 61009, IEC 60269-3 or IEC 60947-2 as long as the requirements in IEC 60898-1 or

IEC 61009 are met for all tests except the test for time-current characteristic B, C and D as specified in

IEC 60898-1:2001, 9.10.1 or IEC 61009-1:2010, clause 9.9.2.1.
8.6.1 Main circuits
Replacement of second paragraph:

Each of the conductors between the incoming unit and outgoing unit as well as the

components included in these units may be rated on the basis of the reduced short-circuit

stresses occurring on the load side of the respective outgoing short-circuit protective device,

provided that these conductors are arranged so that under normal operation an internal short-

circuit between phases and/or between phases and earth is not to be expected (see 8.6.4 of

Part 1).
Addition:

NOTE UK Electricity, Safety and Quality Regulations S.I. 2002 No. 2965 require electricity suppliers to state the

maximum prospective short circuit current at the supply terminals. In the UK the maximum prospective short-circuit

current at the supply terminals of household and similar electrical installations declared by the supply authority in

accordance with the Electricity Association Publication P 25 is 16 kA for single-phase supplies up to and including

100 A.
8.8 Terminals for external conductors
Addition:

The number of neutral terminals of a DBO shall be not less than one outgoing terminal for

each outgoing circuit requiring a neutral terminal. These terminals shall be located or

identified in the same sequence as their respective phase conductor terminals.

DBOs shall have a minimum of two terminals for electrical installation protective bonding

conductors.

NOTE In the USA, the neutral conductor is identified by the colour white and the protective earth conductor may

be either green/yellow or solid green.
9 Performance requirements
This clause of Part 1 applies.
10 Design verification
This clause of Part 1 applies except as follows.
10.2.2.2 Severity test A
Addition:
The following is an alternative test.

All grease is removed from the parts or representative samples of the steel enclosures of the

DBO to be tested, by immersion in a cold chemical degreaser such as methylchloroform or

refined petrol for 10 min. The parts are then immersed for 10 min in a 10 % solution of

ammonium chloride in water at a temperature of (20 ± 5) °C.

Without drying but after shaking off any drops, the parts are placed for 10 min in a box

containing air saturated with moisture at a temperature of (20 ± 5) °C.
---------------------- Page: 11 ----------------------
– 10 – 61439-3 © IEC:2012

After the parts have dried for 10 min in a heating cabinet at a temperature of (100 ± 5) °C and

have been left at room temperature for 24 h, their surfaces shall show no signs of iron

oxidization.

Traces of iron oxide on sharp edges and any yellowish film removable by rubbing are ignored.

For small helical springs and the like, and for inaccessible parts exposed to abrasion, a layer

of grease may provide sufficient protection against iron oxidization. Such parts are subjected

to the test only if there is doubt about the effectiveness of the grease film, and the test is then

made without previous removal of the grease.
10.2.2.4 Results to be obtained

The first paragraph of Part 1 does not apply to the alternative test of this standard.

10.2.3.2 Verification of resistance of insulating materials to abnormal heat and fire due

to internal electric effects
The last paragraph of Part 1 does not apply.
Addition:

NOTE 850 °C does not apply to accessible parts of the enclosure after mounting in hollow walls e.g. covers,

doors.
10.2.6 Mechanical impact
Replacement:

Verification of the degree of protection against mechanical impacts shall be carried out in

accordance with IEC 62262.

The test shall be carried out by means of a hammer test apparatus as described in

IEC 60068-2-75, e.g. impact spring hammer. The test is made after the sample(s) has been

for 2 h at a temperature of –5 °C ± 1 K for indoor use and -25 °C ± 1 K for outdoor use.

Compliance is checked on those exposed parts of the DBO which may be subjected to

mechanical impact when mounted as in normal use.

The sample with cover, or the enclosure, if any, shall be fixed as in normal use or placed

against a rigid support.

Three blows shall be applied on separate places of each of the accessible faces and door (if

provided). The impacts shall be evenly distributed on the faces of the enclosure(s) under test.

In no case shall the impacts be applied in the surroundings of the same point of the

enclosure. A new sample for each accessible face is used, unless the previous test has not

influenced the results of the subsequent test(s), then the sample may be reused. They shall

not be applied to knock-outs, built-in components complying with other standards, or other

fastening means which are recessed below the surface so as not to be subject to impact.

Cable entries which are not provided with knock-outs shall be left open. If they are provided

with knock-outs, two of them shall be opened.

Before applying the blows, fixing screws of bases, covers and the like shall be tightened with

a torque equal to that specified in Table 102.
---------------------- Page: 12 ----------------------
61439-3 © IEC:2012 – 11 –

After the test, visual inspection shall verify that the specified IP code and dielectric properties

have be maintained. Removable covers can still be removed and reinstalled, doors opened

and closed.
10.2.7 Marking
Addition of new first paragraph:
This test only applies to DBO’s intended for outdoor installation.
10.10.2.3.1 General
Addition after the third paragraph:

In the absence of manufacturer’s instructions, the tightening torque applied to terminals shall

be in accordance with those specified for the temperature rise test in the relevant device

product standard.

10.10.2.3.6 Verification considering individual functional units separately and the

complete ASSEMBLY
Addition to fourth paragraph:

One method to determine the most onerous group, is for the rated current of the DBO (I ), to

be distributed amongst the smallest possible number of outgoing circuits, so that each of

these circuits is loaded with its rated current multiplied by the assumed loading factor shown

in Table 101 of this standard or a diversity factor stated by the manufacturer. For an example

considering a complete DBO, see Figure 101.

10.10.2.3.7 Verification considering individual functional units and the main and

distribution busbars separately as well as the complete ASSEMBLY
Addition to item d):

One method to determine the most onerous group, is for the rated current of the DBO (I ), to

be distributed amongst the smallest possible number of outgoing circuits, so that each of

these circuits is loaded with its rated current multiplied by the rated diversity factor shown in

Table 101 of this standard or a diversity factor stated by the manufacturer.
10.10.3.2 ASSEMBLIES
Addition:

DBOs with synthetic enclosures are considered representative of DBOs with metallic

enclosures, if the highest air temperature rise on the inside surfaces of the synthetic

enclosure does not exceed the maximum surface temperature rise for the accessible external

metal surfaces according to Table 6 of Part 1.
10.10.4.2.3 Results to be obtained
Addition:
NOTE Guidance is in the form of a pub
...

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