IEC 61439-3:2012
(Main)Low-voltage switchgear and controlgear assemblies - Part 3: Distribution boards intended to be operated by ordinary persons (DBO)
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
Relations
Standards Content (Sample)
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)
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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)
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX R
ICS 29.130.20 ISBN 978-2-88912-922-5
– 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
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
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
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in the subject dealt with may participate in this preparatory work. International, governmental and non-
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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
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
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expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
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.
– 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.
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
nc
(I ) of the DBO does not exceed 250 A;
nA
– 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
– 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:
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.
– 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.
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.
– 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.
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
nA
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
nA
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 publication of the maximum rated current at a specified ambient air
temperature in the immediate vicinity of the device.
Example:
a) I = 200 A at 40 °C local ambient air temperature, therefore 0,8 × 200 A = 160 A.
th
– 12 – 61439-3 © IEC:2012
b) The calculated air temperature within the enclosure is 60 °C. The manufacturer’s information limits the device
I to 150 A at 60 °C local ambient air temperature.
th
Conclusion: the lower value from a) and b) is the continuous permissible load, in this case 150 A at the
calculated local air temperature.
10.10.4.3.2 Results to be obtained
Addition:
NOTE Guidance is in the form of a publication of the maximum rated current at a specified ambient air
temperature in the immediate vicinity of the device.
Example:
a) I = 200 A at 40 °C local ambient air temperature, therefore 0,8 × 200 A = 160 A.
th
b) The calculated air temperature within the enclosure is 60 °C. The manufacturer’s information limits the device
I to 150 A at 60 °C local ambient air temperature.
th
Conclusion: the lower value from a) and b) is the continuous permissible load, in this case 150 A at the
calculated local air temperature.
10.11.5.3.3 Incoming circuit and main busbars
Addition:
A rated conditional short-circuit current can be assigned where the distance of the main and
distribution busbar between the load terminals of the incoming device connected to the main
busbar and the supply terminals of the outgoing functional unit does not exceed 3 m. The
main busbar, distribution busbar and incoming device may be tested and rated on the basis of
the reduced short-circuit stresses occurring on the load side of the respective short-circuit
protective device within each unit. Provided that these conductors are arranged so that an
internal short-circuit between phases and/or between phases and earth is not to be expected
(see 8.6.4 of Part 1).
NOTE Examples of conductor types and installation requirements are given in Table 4 of Part 1.
10.13 Mechanical operation
Replacement of second paragraph:
For parts, which need verification by test, satisfactory mechanical operation shall be verified
after installation in the DBO. The number of operating cycles shall be 50.
11 Routine verification
This clause of Part 1 applies except as follows.
11.9 Dielectric properties
Addition after the first paragraph:
A dielectric test is not required on a DBO containing busbars and/or prefabricated main circuit
wiring only, nor on simple constructions where inspection of the conductors and cables,
including proper laying is sufficient.
61439-3 © IEC:2012 – 13 –
Additional tables and figure:
Table 101 – Values of assumed loading
Number of outgoing circuits Assumed loading factor
2 and 3 0,8
4 and 5 0,7
6 to 9 inclusive 0,6
10 and above 0,5
Table 102 – Tightening torque values for the verification of mechanical strength
Diameter of thread Tightening torque
a
mm Nm
Metric standard Range of diameters
values “d” b c d
I II III
mm mm
d ≤ 2,8
2,5 0,13 0,26 0,26
2,8 < d ≤ 3,0
3,0 0,16 0,33 0,33
3,0 < d ≤ 3,2
– 0,20 0,40 0,40
3,2 < d ≤ 3,6
3,5 0,26 0,53 0,53
4 3,6 < d ≤ 4,1 0,47 0,80 0,80
4,5 0,53 1,20 1,20
4,1 < d ≤ 4,7
5 0,53 1,33 1,33
4,7 < d ≤ 5,3
6 0,80 1,66 2,00
5,3 < d ≤ 6,0
8 1,66 2,33 4,00
6 < d ≤ 8
10 – 2,66 6,66
8 < d ≤ 10
10 < d ≤ 12
12 – – 9,33
12 < d ≤ 15
14 – – 12,6
16 15 < d ≤ 20 – – 16,6
20 – – 24
20 < d ≤ 24
24 – – 33
24 < d
a
For screws and fasteners made of plastic the tightening torque applied shall be the value
specified in the manufacturer’s instructions. 90 ° locking mechanisms not containing a thread
are not subjected to the tightening torques prescribed in the table, they are operated so as to
engage in normal use.
b
Column I applies to screws without heads which, when tightened, do not protrude from the hole
and to other screws which cannot be tightened by means of a screwdriver with a blade wider
than the root diameter of the screw.
c
Column II applies to nuts and screws, which are tightened by means of a screwdriver.
d
Column III applied to nuts and screws, which can be tightened by means other than a
screwdriver.
– 14 – 61439-3 © IEC:2012
Rated current of the DBO: InA 100 A
Outgoing
Outgoing unit 1 Inc 80 A
unit 1
Outgoing unit 2 Inc 80 A
Inc 80 A
TEST
Outgoing functional units Inc 63 A maximum
current
Total outgoing circuits in DBO = 8
80 A
From Table 101 assumed loading factor for 8
outgoing circuits = 0,6
Test currents:
Main incoming unit = 100 A
Outgoing unit 1 = test current 80 A
1 1 1 1
a b c d
Test current 1a = 63 A × 0,6 = 37,8 A
Main incoming unit
Test current 1b = 63 A × 0,6 = 37,8 A
Rated current of the
Test current 1c = 6 A = 4,4 A
DBO (InA) 100 A
Total 80 A
TEST current 100 A
Circuit 1c is the balance current to load the
outgoing unit 1 to its rated circuit current (Inc), so as
to achieve the highest temperature rise.
Outgoing unit 2 = test current 20 A, which is the
Outgoing
balance to obtain incoming circuit InA so as to
unit 2
achieve the highest temperature rise. Therefore
Inc 80 A
outgoing circuit 2a = 32 A × 0,6 = 19,2 A
TEST
and 2b = 2 A loaded to 0,8 A (balance)
current 20 A
NOTE 1
This is one example where the DBO is loaded to its
rated current (InA). More tests in different
configurations may be required.
2 2 2 2 NOTE 2
Outgoing
a b c d
In DBOs, where the total of the rated currents of the
functional unit
outgoing circuits operating at rated diversity factor,
exceeds the capacity of the incoming circuit, the
diversity factor applies to any combination of
outgoing circuits used to distribute the incoming
current.
In Figure 101, 1a to 1d each
Outgoing
63 A = (63 × 4) × 0,6 = 151,2 A, which exceeds the
circuit
capacity of the 100 A incoming circuit.
Therefore, in this example, outgoing circuits are
loaded to the Inc of outgoing unit 1(80 A), with
outgoing unit 2 loaded to the balance of the
incoming circuit (20 A).
NOTE 3
The rated current of a functional unit (the circuit) is the
value of current, declared by the ASSEMBLY
manufacturer, which may be lower than the rated current
of the device according to the respective device
standard.
IEC 177/02
Figure 101 – Example of temperature rise verification
by test of a complete DBO as in 10.10.2.3.6
61439-3 © IEC:2012 – 15 –
Annexes
Annexes of Part 1 apply except as follows.
Annex D
(informative)
Design verification
Annex D of Part 1 does not apply.
Additional annex:
– 16 – 61439-3 © IEC:2012
Annex AA
(informative)
Items subject to agreement between
the ASSEMBLY manufacturer and the user
The information given in Table AA.1 is subject to an agreement between the ASSEMBLY
manufacturer and the user. In some cases information declared by the ASSEMBLY
manufacturer may take the place of an agreement.
Table AA.1 – Items subject to agreement between
the ASSEMBLY manufacturer and the user
Reference
Default Options listed in User
Characteristics clause or
b a
arrangement standard requirement
subclause
Electrical system
Earthing system 5.6, 8.4.3.1, Manufacturer’s TT / TN-C / TN-C-
8.4.3.2.3, 8.6.2, standard, S / IT, TN-S
10.5, 11.4 selected to suit
local
requirements
Nominal voltage of the power supply (V) 3.8.9.1, 5.2.1, Local, according Rated voltage to
8.5.3 to installation
earth ≤ 300 V a.c.
conditions
Transient overvoltages 5.2.4, 8.5.3, 9.1, Determined by Overvoltage
the electrical
Annex G category III
system
Temporary overvoltages 9.1 Nominal system None
voltage + 1 200 V
Rated frequency f (Hz) 3.8.11, 5.4, According to local 50 Hz/60 Hz
n
8.5.3, 10.10.2.3, installation
10.11.5.4 conditions
Additional on site testing requirements: 11.10 Manufacturer’s None
wiring, operational performance and standard,
function according to
application
Short-circuit withstand capability
Prospective short-circuit current at 3.8.7 Determined by None
supply terminals I (kA) the electrical
cp
system
Prospective short-circuit current in the 10.11.5.3.5 Min. 60 % of None
neutral phase values
Prospective short-circuit current in the 10.11.5.6 Min. 60 % of None
protective circuit phase values
SCPD in the incoming functional unit 9.3.2 According to local Yes / No
requirement installation
conditions
Co-ordination of short-circuit protective 9.3.4 According to local None
devices including external short-circuit installation
protective device details conditions
Data associated with loads likely to No loads likely to
9.3.2 None
contribute to the short-circuit current make a
significant
contribution
allowed for
61439-3 © IEC:2012 – 17 –
Reference
Default Options listed in User
Characteristics clause or
b a
arrangement standard requirement
subclause
Protection of persons against electric
shock in accordance with
IEC 60364-4-41
8.4.2 Basic protection According to local
Type of protection against electric shock
installation
– Basic protection (protection against
regulations
direct contact)
Type of protection against electric shock 8.4.3 According to local Automatic
– Fault protection (protection against installation disconnection of
indirect contact) conditions supply / Electrical
separation / Total
insulation
Installation environment
Location type 3.5, 8.1.4, 8.2 Manufacturer’s Indoor / outdoor
standard,
according to
application
8.2.2, 8.2.3 Indoor 2XC, 3X, 4X, 5X,
Protection against live parts, ingress of
(enclosed): 6X
solid foreign bodies and water
IP 2XC
After removal of
Outdoor (min.): removable parts:
IP 23
As for connected
position / Reduced
protection
to manufacturer’s
standard
External mechanical impact (IK) 8.2.1, 10.2.6 Indoor IK 05 None
Outdoor IK 07
Resistance to UV radiation (applies for 10.2.4 Indoor: Not
outdoor assemblies only unless applicable
specified otherwise)
Outdoor:Tempera
te climate
Resistance to corrosion 10.2.2 Normal
Indoor/Outdoor
arrangements
Ambient air temperature – Lower limit 7.1.1 Indoor: –5 °C None
Outdoor: –25 °C
Ambient air temperature – Upper limit 7.1.1 40 °C None
Ambient air temperature – Daily 7.1.1, 9.2 35 °C None
average maximum
Maximum relative humidity 7.1.2 Indoor: 50 % None
at 40 °C
Outdoor: 100 %
at 25 °C
Pollution degree (of the installation 7.1.3 2
environment)
Altitude 7.1.4 ≤ 2 000 m
EMC environment (A or B) 9.4, 10.12, A/B A/B
Annex J
Special service conditions (e.g. 7.2, 8.5.4, 9.3.3 No special
vibration, exceptional condensation, Table 7 service conditions
heavy pollution, corrosive environment,
strong electric or magnetic fields,
fungus, small creatures, explosion
hazards, heavy vibration and shocks,
earthquakes)
– 18 – 61439-3 © IEC:2012
Reference
Default Options listed in User
Characteristics clause or
b a
arrangement standard requirement
subclause
Installation method
Type 3.3, 5.6 Manufacturer’s Various e.g. floor
standard standing / wall
mounted
Stationary/Movable 3.5 Stationary
Maximum overall dimensions and weight 5.6, 6.2.1 Manufacturer’s
standard,
according to
application
Manufacturer’s Cable / Busbar
External conductor type(s) 8.8
standard Trunking System
Direction(s) of external conductors 8.8 Manufacturer’s
standard
External conductor material 8.8 Copper Copper /
Aluminium
External phase conductor, cross 8.8 As defined within
sections, and terminations the standard,
External PE, N, PEN conductors cross 8.8 As defined within
sections, and terminations the standard,
Special terminal identification 8.8 Manufacturer’s
requirements standard
Storage and handling
Maximum dimensions and weight of 6.2.2, 10.2.5 Manufacturer’s
transport units standard
Methods of transport (e.g. forklift, 6.2.2, 8.1.6 Manufacturer’s
crane) standard
Environmental conditions different from 7.3 As service
the service conditions conditions
Packing details 6.2.2 Manufacturer’s
standard
Operating arrangements
Access to manually operated devices 8.4, 8.5.3 Ordinary persons
Location of manually operated devices 8.5.5 Easily accessible
61439-3 © IEC:2012 – 19 –
Reference
Default Options listed in User
Characteristics clause or
b a
arrangement standard requirement
subclause
Maintenance and upgrade capabilities
Requirements related to accessibility in 8.4.6.1 Basic protection
service by ordinary persons;
requirement to operate devices or
change components while the ASSEMBLY
is energised
Requirements related to accessibility for 8.4.6.2.2 No requirements
inspection and similar operations for accessibility
Requirements related to accessibility for 8.4.6.2.3 No requirements
maintenance in service by authorized for accessibility
persons
Requirements related to accessibility for 8.4.6.2.4 No requirements
extension in service by authorized for accessibility
persons
8.5.1, 8.5.2 Manufacturer’s
Method of functional units connection
standard
Protection against direct contact with 8.4 No requirements
hazardous live internal parts during for protection
maintenance or upgrade (e.g. functional during
units, main busbars, distribution maintenance or
busbars) upgrade
Current carrying capability
Rated current of the ASSEMBLY I 3.8.9.1, 5.3,
≤ 250 A
nA
(amperes) 8.4.3.2.3, 8.5.3,
8.8, 10.10.2,
10.10.3,
10.11.5,
Annex E
Rated current of circuits I (amperes) 5.3.2 ≤ 125 A
nc
Rated diversity factor 5.4, 10.10.2.3, As defined within RDF for groups of
Annex E the standard circuits / RDF for
whole ASSEMBLY
8.6.1 100 %
Ratio of cross section of the neutral
conductor to phase conductors: phase
conductors up to and including 16 mm
8.6.1 50 %
Ratio of cross section of the neutral
(min. 16 mm )
conductor to phase conductors: phase
conductors above 16 mm
a
For exceptionally onerous applications, the user may need to specify more stringent requirements to those in the
standard.
b In some cases information declared by the ASSEMBLY manufacturer may take the place of an agreement.
– 20 – 61439-3 © IEC:2012
Bibliography
The bibliography of Part 1 applies except as follows.
Addition:
IEC 60947-2, Low-voltage switchgear and controlgear – Part 2: Circuit-breakers
IEC 61009-1:2010, Residual current operat
...
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