IEC 60092-302-2:2025

IEC 60092-302-2 ®
Edition 2.0 2025-10
INTERNATIONAL
STANDARD
REDLINE VERSION
Electrical installations in ships -
Part 302-2: Low voltage switchgear and controlgear assemblies - Marine power
ICS 47.020.60 ISBN 978-2-8327-0780-7
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.

IEC Secretariat Tel.: +41 22 919 02 11
3, rue de Varembé info@iec.ch
CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigendum or an amendment might have been published.

IEC publications search - IEC Products & Services Portal - products.iec.ch
webstore.iec.ch/advsearchform Discover our powerful search engine and read freely all the
The advanced search enables to find IEC publications by a publications previews, graphical symbols and the glossary.
variety of criteria (reference number, text, technical With a subscription you will always have access to up to date
committee, …). It also gives information on projects, content tailored to your needs.
replaced and withdrawn publications.
Electropedia - www.electropedia.org
The world's leading online dictionary on electrotechnology,
IEC Just Published - webstore.iec.ch/justpublished
Stay up to date on all new IEC publications. Just Published containing more than 22 500 terminological entries in English
details all new publications released. Available online and and French, with equivalent terms in 25 additional languages.
once a month by email. Also known as the International Electrotechnical Vocabulary
(IEV) online.
IEC Customer Service Centre - webstore.iec.ch/csc
If you wish to give us your feedback on this publication or
need further assistance, please contact the Customer
Service Centre: sales@iec.ch.
CONTENTS
FOREWORD . 2
INTRODUCTION . 1
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 8
4 Symbols and abbreviations . 8
5 Interface characteristics . 9
6 Information . 9
7 Service conditions . 10
8 Constructional requirements . 11
9 Performance requirements . 14
10 Design verification . 15
11 Routine verification . 17
Annexes . 18
Annex J – Electromagnetic compatibility (EMC) . 27
Annex AAA (informative) Items subject to agreement between the assembly
manufacturer and the user . 28
Bibliography . 33

Figure 201 – Relationship of standards . 6

Table 1 – Minimum clearances in air (8.3.2) . 22
Table 2 – Minimum creepage distances for marine applications main and emergency
switchboards (8.3.3) . 22
Table 201 – Earth continuity of doors, lids or similar . 23
Table 6 – Temperature-rise limits (9.2) . 24
Table 13 – Short-circuit verification by comparison with reference design: check list
(IEC 61439-1:2020, 10.5.3.3, 10.11.3 and 10.11.4) . 25
Table 15 – Climatic conditions . 25
Table AAA.1 – Items subject to agreement between the assembly manufacturer and
the user . 28
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Electrical installations in ships -
Part 302-2: Low voltage switchgear and controlgear assemblies -
Marine power
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 Publication(s)”). Their
preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
may participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. IEC collaborates closely 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
misinterpretation by any end user.
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.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
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) 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
respect thereof. As of the date of publication of this document, IEC had not received notice of (a) patent(s), which
may be required to implement this document. However, implementers are cautioned that this may not represent
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.
This redline version of the official IEC Standard allows the user to identify the changes made
to the previous edition IEC 60092-302-2:2019. A vertical bar appears in the margin wherever a
change has been made. Additions are in green text, deletions are in strikethrough red text.

IEC 60092-302-2 has been prepared by IEC technical committee 18: Electrical installations of
ships and of mobile and fixed offshore units. It is an International Standard.
This second edition cancels and replaces the first edition published in 2019. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) amended and updated in line with, and correctly referenced to the updated clauses of IEC
61439-1:2020 and IEC 61439-2:2020;
b) explanation of the need to special consideration for marine applications added;
c) Figure 201 updated;
d) adjustment has been made to the "safety factors" for creepage and clearance distances.
The text of this International Standard is based on the following documents:
Draft Report on voting
18/1994/FDIS 18/2007/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 International Standard is to be used in conjunction with IEC 61439-1:2020 and
IEC 61439-2:2020.
This document supplements or modifies the corresponding clauses in IEC 61439-1:2020 and
IEC 61439-2:2020. Where this document states "addition", "deletion", "replacement" or
“amendment”, the relevant text of IEC 61439-1:2020 and IEC 61439-2:2020 is adapted
accordingly. When no modification of the text of IEC 61439-1:2020 is in IEC 61439-2:2020, the
modification in this document is referred directly to the IEC 61439-1:2020.
Clauses and subclauses which are additional to those of IEC 61439-1:2020 and
IEC 61439-2:2020 are numbered starting from 201. Additional annexes are numbered starting
from AAA.
In this document, terms written in small capitals are defined in Clause 3.
Where the abbreviated term PSC-assembly is used in applicable clauses of IEC 61439-2:2020,
this refers to MPSC-assembly.
A list of all parts in the IEC 60092 series, published under the general title Electrical
installations in ships, 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, or
– revised.
INTRODUCTION
This part of IEC 60092 forms a series of International Standards for electrical installations in
sea-going ships, incorporating good practice and coordinating, as far as possible, existing rules.
These standards form a code of practical interpretation and amplification of the requirements
of the International Convention for the Safety of Life at Sea, a guide for future regulations which
may can be prepared and a statement of practice for use by ship owners, shipbuilders and
appropriate organizations.
The IEC 61439 series identifies specifies the requirements for land based low voltage
switchgear and controlgear assemblies. The IEC 60092-302 series has been developed in line
with Figure 201, which shows the future intention to develop appropriate marine standards for
final distribution boards to be operated by ordinary persons; and busbar trunking systems
illustrates opportunities to develop relevant marine standards.
The IEC 60092 series remains the principal series of standards for electrical installations in
ships, and the applicable standards are applied accordingly. Wherever there are differences
between the IEC 61439 series and the IEC 60092 series, the IEC 60092 series takes
precedence.
IEC 61439-1
IEC 61439-2 IEC 61439-3 IEC 61439-4 IEC 61439-5 IEC 61439-6
IEC IEC IEC
60092 302 2
IEC60092 60092
Si
IEC
Key
a
Under consideration.
NOTE At the time of publication, IEC 60092-302-3 and IEC 60092-302-6 are not developed. The figure shows that
these standards are potential future projects to align with the IEC 61439 series.

Figure 201 – Relationship of standards
1 Scope
This part of IEC 60092 defines the specific requirements of low voltage marine power
switchgear and controlgear assemblies (MPSC-assemblies) as follows:
– stationary assemblies with enclosure for which the rated voltage does not exceed
1 000 V AC or 1500 V DC;
– assemblies intended for use in conjunction with the power generation, distribution and
conversion of electric energy, and for the control of electric energy consuming equipment.
Due to the marine application and the risks associated with loss of power, additional safety
factors have been applied to minimise the risk of failure, such as applying an additional safety
factor on clearance distances.
This document applies to all assemblies whether they are designed, manufactured and verified
on a one-off basis or fully standardised and manufactured in quantity.
Either the manufacture and/or assembly, or both, of the MPSC assembly can be carried out by
others than by the original manufacturer.
This document does not apply to individual devices and self-contained components, such as
motor starters, fuse switches, electronic equipment, which comply with the relevant product
standards.
NOTE Individual devices and components include those that are covered by the IEC 60947 series.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60092 (all parts), Electrical installations in ships
IEC 60092-101:2018, Electrical installations in ships - Part 101: Definitions and general
requirements
IEC 60092-201:2019, Electrical installations in ships - Part 201: System design - General
IEC 60533, Electrical and electronic installations in ships - Electromagnetic compatibility (EMC)
- Ships with a metallic hull
IEC 61439-1:20112020, Low-voltage switchgear and controlgear assemblies - Part 1: General
rules
IEC 61439-2:20112020, Low-voltage switchgear and controlgear assemblies - Part 2: Power
switchgear and controlgear assemblies
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
– IEC Electropedia: available at http://www.electropedia.org/
– ISO Online browsing platform: available at http://www.iso.org/obp
Clause 3 of IEC 61439-2:20112020 is applicable except as follows.
3.1 General terms
Additional terms and definitions:
3.1.201
marine power switchgear and controlgear assembly
MPSC-assembly
low-voltage switchgear and controlgear assembly used to distribute and control energy for all
types of loads, intended specifically for marine applications specifically, in on ships, operated
by skilled or instructed persons only
Note 1 to entry: It is not excluded for a MPSC-assembly to be located in an area accessible to ordinary persons.
3.1.202
main switchboard
MPSC-assembly which is directly supplied by the main source of electrical power and is intended
to control and distribute electrical energy to the ship's services
3.1.203
motor control centre
MCC
MPSC-assembly which is supplied by main or emergency switchboards and is intended to control
and distribute electrical energy
Note 1 to entry: It is possible for the MCC to be a section or sections of the main switchboard.
3.1.204
emergency switchboard
MPSC-assembly which is normally supplied by the main switchboard but, in the event of failure
of the main electrical power system, is directly supplied by the emergency source of electrical
power and is intended to control and distribute electrical energy to the emergency services
3.1.205
distribution board
MPSC-assembly which is supplied by a main or emergency switchboard, or distribution boards
and is used to distribute and control energy to other distribution boards, final distribution boards
or final sub circuits
Note 1 to entry: The definition of "section board" as defined in previous versions of IEC 60092-302 has been
replaced by the one of "distribution board".
4 Symbols and abbreviations
Clause 4 of IEC 61439-2:20112020 is applicable.
5 Interface characteristics
IEC 61439-2:20112020, Clause 5, is applicable except as follows.
5.2 Voltage ratings
5.2.3 Rated insulation voltage (U ) (of a circuit of an assembly)
i
Replacement of IEC 61439-1:20112020, 5.2.3:
The rated insulation voltage of a circuit of an assembly is the voltage value to which dielectric
test voltages and creepage distances are referred.
Due to the potential effects of the marine environment on creepage distances, the rated
insulation voltage of a circuit shall be 1,5 times higher than the values stated for U and for U
n e
for the same circuit up to a final maximum of U 1 000 V AC or 1 250 V DC. Any DC application
i
requiring U exceeding 1 250 V DC shall need to have special consideration.
i
Due to the criticality of power availability for main and emergency switchboards, a multiplication
factor of 1,5 times has been applied for required creepage distances (see Table 2 where the
factor is applied). For single-phase circuits derived from IT systems (see IEC 60364-5-52), the
rated insulation voltage should be at least equal to the voltage between phases of the supply.
While it is advisable to use the above safety factor for all internal components and devices, it
is not a requirement for those that have been tested in accordance with their own product
standard need not to have this safety factor applied.
NOTE A safety factor has intentionally not been applied to the dielectric test voltage requirements to maintain
compatibility with product standards.
5.6 Other characteristics
Replacement of item g) of IEC 61439-1:2011:
g) operated by skilled and instructed persons only;
5.5 Rated frequency (f )
n
Replacement of the second paragraph of IEC 61439-1:2020, 5.5:
The frequency should be within the limits specified in IEC 60092-101 for the incorporated
components. The tolerance shall be within 95 % and 105 % of the rated frequency.
6 Information
IEC 61439-2:20112020, Clause 6, is applicable except as follows.
6.1 Assembly designation marking
Replacement of IEC 61439-1:2020, 6.1, item d):
d) IEC 60092-302-2;
Addition of item eh):
eh) ambient air temperature (see 7.1.1.1 and 7.1.1.2).
6.3 Device and/or component identification
Addition to IEC 61439-1:2020, 6.3:
Individual circuits and their devices shall have the following durable and permanent markings
and meet the requirements of IEC 60092-201:2019, 5.3:
a) rated current of the circuit I and assigned settings of adjustable protective devices (see
nc
IEC 61439-1:20112020, 6.2.2, for documentation of settings requirements);
b) when, for fuse systems above 500 V, the fuseholders permit the insertion of fuse links for
lower rated voltage, special warning labels or symbols, for example "Caution 690 V fuse
links only".
c) arranging warning labels where polarized circuit-breakers are installed in DC systems to
guard against the possibility of incorrect connections during maintenance or replacement;
d) permanent markings on withdrawable and/or removable parts along with relevant fixed parts
of an assembly shall be provided with permanent markings in order to identify where the
parts can be correctly reassembled.
Compliance is checked according to the test of IEC 61439-1:20112020, 10.2.7, and by
inspection.
7 Service conditions
IEC 61439-1:20112020, Clause 7, is applicable except as follows.
7.1.1.1 Ambient air temperature for indoor installations
Replacement:
The ambient air temperature does not exceed +45 °C, and its average over a period of 24 h
does not exceed +40 °C.
The lower limit of the ambient air temperature is 5 °C.
NOTE Where the ambient air temperature of the assembly is different, details of calculation methods are given in
10.10.3.201.
7.1.1.2 Ambient air temperature for outdoor installations
Replacement:
The ambient air temperature does not exceed +45 °C, and its average over a period of 24 h
does not exceed +40 °C.
The lower limit of the ambient air temperature is –25 °C.
NOTE Where the ambient air temperature of the assembly is different, details of calculation methods are given in
10.10.3.201.
7.1.2.1 Humidity conditions for indoor installations
Replacement:
In other parts of the IEC 60092 series, where no "high air temperature" has been specified as
a design parameter for equipment, the relative humidity of the air does not exceed 95 % at a
maximum temperature of +45 °C.
Moderate condensation should be borne in mind which can occasionally occur due to variations
in temperature.
7.1 Normal service conditions
7.1.1 Climate conditions
Amendment, in the first paragraph:
Table 15 of this document applies.
7.1.2 Pollution degree
Addition to IEC 61439-1:2020, 7.1.2:
For ships, pollution degree 3 is applicable. If lower pollution degree is required, this has to be
proven by evidence.
Additional subclauses to IEC 61439-1:2020, 7.1:
7.1.201 Vibration
MPSC-assemblies shall be unaffected by vibration likely to occur under normal service. Design
parameters are detailed in 4.6.3.5 of IEC 60092-101:2018, 4.6.3.5, shall apply.
7.1.202 Angular deviation and motion
MPSC-assemblies shall be unaffected by movement of the ship likely to occur under normal
service. Design parameters are detailed in 4.6.3.4 of IEC 60092-101:2018, 4.6.3.4, shall apply.
8 Constructional requirements
IEC 61439-2:20112020, Clause 8, is applicable except as follows.
8.2.2 Protection against contact with live parts, ingress of solid foreign bodies and
water
Deletion of Note 1 in 8.2.2 of IEC 61439-1:2011.
8.3.2 Clearances
Deletion of the note in 8.3.2 of IEC 61439-1:2011.
8.3.3 Creepage distances
Replacement of the third paragraph in 8.3.3 of IEC 61439-1:2011:
Creepage distances shall correspond to a pollution degree as specified in 7.1.3 and to the
corresponding material group at the rated insulation voltage given in Table 2. Devices that have
been tested in accordance with their own product standard need not have this safety factor
applied.
Deletion of Note 2 in 8.3.3 of IEC 61439-1:2011.
8.4.2.3 Barriers or enclosures
Replacement of IEC 61439-1:2020, 8.4.2.3, item b):
After isolation of the supply to live parts, against which the barriers or enclosures afford basic
protection, restoration of the supply being possible only after replacement or reclosure of the
barriers or enclosures.
8.4.3 Fault protection
8.4.3 of IEC 61439-1:2011 is applicable except as follows.
IEC 61439-2:2020, 8.4.3, is applicable except as follows.
8.4.3.2.2 Requirements for earth continuity providing protection against the
consequences of faults within the class I assembly
Addition, under item b):
NOTE The requirements for doors, lids and similar have been organized in Table 201.
Additional paragraph subclause:
8.4.3.201 Protection against electric shock for maintenance accessibility maintenance
If earth bars (protective conductor) are installed in main and or emergency switchboards, MCCs
and distribution boards, the earth bar shall be installed and located to ensure their easy access
and access to their terminations, during and after installation. When switchgear or controlgear
are located behind the doors of the assemblies, live parts shall be protected against inadvertent
touching by means of barriers or enclosure having at least IP2X.
8.4.6 Operating and servicing conditions
8.4.6 of IEC 61439-1:2011 is applicable except as follows.
8.4.6.2.3 Requirements related to accessibility for maintenance
Addition to IEC 61439-1:2020, 8.4.6.2.3:
It shall be possible to replace or maintain all devices a device used for isolation of the its main
source of electrical power without complete blackout of the main source of electrical power ship.
NOTE See IEC 60092-201:2019, Clause 8.
Where polarized circuit breakers are installed in DC systems, and in all other similar cases,
warning labels shall be arranged to guard against the possibility of incorrect connection during
maintenance.
8.5 Incorporation of switching devices and components
8.5 of IEC 61439-1:2011 is applicable except as follows.
8.5.4 Installation of switching devices and components
Addition to IEC 61439-1:2020, 8.5.4:
Wherever possible, components of main circuits with different nominal voltages shall be
installed separate from each other separately with internal separation provided for each level
of voltage.
8.6 Internal electrical circuits and connections
8.6 of IEC 61439-1:2011 is applicable except as follows.
8.6.2 Auxiliary circuits
Addition to IEC 61439-1:2020, 8.6.2:
Wiring shall comply with the relevant requirements given in the cable standards within the
IEC 60092 series. Other types of cable or wire may be used if the IEC 60092 series does not
cover this type of cable or wire, provided these meet the applicable IEC product Standards and
are suitable for marine application.
8.6.3 Bare and insulated conductors
Addition to IEC 61439-1:2020, 8.6.3:
Cables shall comply with the relevant requirements given in the cable standards within the
IEC 60092 series. Other types of cable or wire may be used if the IEC 60092 series does not
cover this type of cable or wire, provided these meet the applicable IEC product Standards and
are suitable for marine application.
Additional subclauses to IEC 61439-1:2020, 8.6.3:
8.6.3.201 Busbars
8.6.3.201.1 General
Busbars shall be of a composition suited for operation in a salt-laden atmosphere.
EXAMPLE Electrolytic copper or copper-clad aluminium.
8.6.3.201.2 Sub-division of main switchboard main busbar
The MPSC-assembly shall meet the specific requirement of the system as detailed in
IEC 60092-201:2019, Clause 8.
Where there is a functional requirement for more than one incoming device within the assembly,
the main busbars of the assembly shall be subdivided into at least two isolated parts; this is to
be done by an appropriate isolation device such as a multipole switch disconnector or circuit
breaker.
8.6.3.201.3 Busbar phase or polarity arrangements
Where practicable, a the following standard pattern of busbar phase and polarity arrangements
shall be used. Examples for such a pattern as viewed from the front of the assembly are as
follows:
a) For AC MPSC-assemblies, busbar L1, L2, L3. counting shall be counted from front to rear,
top to bottom or left to right (when viewed from the front of the switchgear assembly).
b) Polarities on DC switchgear and controlgear busbars and connections to shall be positive,
neutral and negative, counting from front to rear, top to bottom or left to right.
8.8 Terminals for external conductors
Deletion of Note 1 of IEC 61439-1:2011.
8.101 Internal separation of PSC-assemblies
8.101 of IEC 61439-2:2011 is applicable except as follows.
Addition after the second first paragraph:
Incoming and section interconnection devices and any circuit with I above 600 A used within
nc
main and emergency switchboards shall be contained in their own compartment providing at
least a degree of protection of IP XXB.
Replacement of Note 1:
NOTE 1 The degree of protection IP 2X covers the degree of protection IP XXB.
Deletion of Note 2.
Additional subclauses:
8.201 Constructional requirements for marine applications
8.201.1 Structural parts of aluminium alloy
If aluminium alloy is used in construction, the material shall be suitable for the use in the marine
environment, and precautions. Measures shall be taken to avoid galvanic corrosion, especially
where in contact with other materials.
8.201.2 Handrails or handles
Every main or emergency switchboard, MCC and distribution board required for essential and
emergency services shall be provided with an insulated handrail or insulated handles to enable
these assemblies to be operated safely during the vessels possible motion. These should be
suitably located on a fixed part on the front of the assemblies. Where access to the rear of the
above-mentioned switchboards is necessary for operational, maintenance, or similar purposes,
an insulated handrail or insulated handles should be suitably located on a fixed part of the
assembly.
8.201.3 Door latching
Hinged doors which may require to be opened for operation, maintenance or similar purposes
shall be provided with a latching or locking facility to keep the door open during normal
movement of the ship.
9 Performance requirements
IEC 61439-2:20112020, Clause 9, is applicable except as follows.
9.1.3.1 Impulse withstand voltages of main circuits
Addition at the end of IEC 61439-1:20112020, 9.1.3.1:
The rated impulse withstand voltage for a given rated operational voltage shall not be less than
that corresponding in IEC 61439-1:2020, Annex G, to the nominal voltage of the supply system
of the circuit at the point where the assembly is to be used and with the overvoltage category III.
9.2 Temperature-rise limits
Delete Note 2 of IEC 61439-1:2011.
Addition at the end of IEC 61439-1:20112020, 9.2:
The temperature-rise limits given in Table 6 of this document apply for a mean ambient daily
average air temperature up to 40 °C. MPSC-assemblies are required to operate in a higher
ambient temperature under service conditions (see 7.1) (see Table 15 of this document). A
reduction of the permissible rises shown to reflect the raised ambient should be made. During
verification, a different ambient air temperature is permissible (see IEC 61439-1:2020,
10.10.2.3.4).
NOTE For environments exceeding 40 °C, additional cooling devices such as fans or air conditioning can be
considered to ensure safe operation of the equipment.
10 Design verification
Clause 10 of IEC 61439-1:2011 is applicable with the following additions.
10.10.2.3.1 General
Addition:
To reduce the testing required to determine the rated current of a circuit I at the maximum
permissible temperature rise ∆T , the current rating may be calculated from the actual test
current I if the measured temperature rise ∆T of the current carrying parts (e.g. busbars and
2 2
terminals) deviates from the permissible value by not more than ±5 K, using the following
formula :
0.61
 
I ∆T
1 1
 
=
 
I ∆T
2  2 
where
I is the current at which the temperature rise test is carried out;
I is the current rating to be determined at the specific ambient air temperature between
20 °C and 55 °C;
∆T is the temperature rise measured by test with a current of I ;
1 1
∆T is the maximum permissible temperature rise at the specific ambient air temperature
between 20 °C and 55 °C.
NOTE The formula can only be applied if the power loss of the devices and conductors is substantially proportional
to I .
Care shall be taken to ensure that all other measurement points will not reach their maximum
temperature at this higher current. The most critical location of highest temperature point shall
be identified either by test or thermal simulation.
Care is required when determining the number of points where this calculation is applied so as
to ensure the effects of changing several currents having an influence on other measuring
points (including internal air temperature) due to the changed power loss.
___________
Formula reproduced from Copper Development Association, Publication No. 22:1996, with the permission of
Copper Development Association Inc.
10.10.3.5 Functional units – Device substitution
Replacement of 10.10.3.5 of IEC 61439-1:2011, including its title
10.10.3.5 Functional units – Temperature-rise considerations for device substitution
A device within a circuit may be substituted with a similar device from another series from the
same or a different device manufacturer to that used in the original verification, provided that
the power loss and terminal temperature rise of the substituting device is the same or lower
than the device used in the original verification, when both are tested in accordance with the
devices' product standard.
Alternatively, the substitution is possible if the following conditions are met.
a) The temperature rise at the terminals of the original device, when tested in the assembly,
is at least 10 K below the limit permitted by the assembly standard.
a) The substituting device has a temperature rise limit on the terminals declared by the
manufacturer of the substituting device, no less than the temperature rise limit on the
terminals declared by the manufacturer of the original device. If there is no declared
temperature rise limit, the default temperature rise limit is that permitted by the device
standard.
b) The power loss of the substituting device does not exceed that of the original device.
Alternatively, when the original device and the substituted device are from the same device
manufacturer, the device manufacturer may issue a declaration of temperature rise
performance. The declaration shall confirm that the substituting device can replace the original
device with no further need for verification in respect of temperature rise.
In addition, for each of the above options, the physical arrangement within the functional unit
shall be maintained. The rating of a functional unit shall not be increased. The physical
arrangements shall include terminal shields, conductor type, material, and connection sizes,
mounting orientation, clearances to other parts, ventilation arrangements and terminal
arrangement.
The performance data on terminal temperatures and power loss may be obtained from the
device manufacturer or from comparison tests undertaken by those responsible for the
substitution. Any test shall be conducted on new samples.
Refer to Table D.1 for other design characteristics, including short-circuit withstand, that require
consideration when substituting devices.
10.1 General
Replacement of the eleventh paragraph, beginning with "The performance of the assembly" of
IEC 61439-1:2020, 10.1:
It is possible that the assembly is affected by the verification tests (e.g. short-circuit test). In
normal circumstances, these tests should not be performed on an assembly that is intended to
be placed in service. However, if the assembly is intended to be put in service, extensive checks
shall be conducted to determine if no detrimental consequences have occurred due to the test.
If these have occurred, the affected part shall be replaced.
NOTE For small series, it is not feasible to build an additional switchboard only for testing purposes.
10.9.3.5 Verification assessment
Replacement of IEC 61439-1:2020, 10.9.3.5:
Clearances shall be verified by measurement, or verification of measurements on design
drawings, employing the measurement methods stated in IEC 61439-1:2020, Annex F. The
clearances shall be at least the values specified in Table 1.
It shall be verified by assessment of the device manufacturer's data that all incorporated devices
are suitable for the specified rated impulse withstand voltage (U ).
imp
10.10.3.20110.10.3.6 Calculation of currents based on adjustment of ambient air
temperature
Replacement of IEC 61439-1:2020, 10.10.3.6:
To facilitate the probable variation of locations of an assembly in the vessel, the following
methodology may can be used the to adjust the rated current of the assembly. Once a
temperature rise test has been carried out applying the temperature rise limits for a daily
average ambient air temperature of 40 °C, then up to a daily average ambient air temperature
of 55 °C, the rated currents verified by testing can be adjusted by calculation, assuming that
the over-temperature of each component or device is proportional to the power loss generated
in this component.
Caution should be taken to ensure the devices being assessed have a power loss substantially
proportional to I and which is not applied to devices that have substantially fixed losses. By
agreement between the user and the manufacturer, in assemblies where the power loss of
conductors and devices is substantially proportional to I , the rated current of the circuits at
ambient air temperatures (outside the enclosure) between 20 °C and 55 °C may can be
calculated using the following formula :
0,61

IT∆
=

IT∆
22
where
I is the current at which the temperature rise test is carried out;
I is the current rating to be determined at the specific ambient air temperature between
20 °C and 55 °C;
∆T is the temperature rise measured by test with a current of I ;
1 1
∆T is the maximum permissible temperature rise at the specific ambient air temperature
between 20 °C and 55 °C.
I cannot exceed 95 % of the rated current of any device within the circuit being considered; for
example, a circuit including a 1 600 A circuit-breaker cannot be assigned a current rating
greater than 1 520 A.
11 Routine verification
IEC 61439-2:20112020, Clause 11, is applicable except as follows.
___________
Formula Reproduced from Copper Development Association, Publication no. 22:1996, Formula (8), with the
permission of Copper Development Association Inc.
Table 1 – Minimum clearances in air (8.3.2)
Replace Table 1 of IEC 61439-1:2011 with the following
Table 1 – Minimum clearances in air (8.3.2)
a
Rated impulse withstand voltage,
Minimum clearance
U
imp
kV mm
≤ 2,5 4
4,0 8
6,0 14
8,0 20
12,0 35
a
Based on inhomogeneous field conditions and pollution degree 3.
NOTE This table reflects a safety multiplication factor to take into account the

marine environment.
Table 2 – Minimum creepage distances (8.3.3)
Replace Table 2 of IEC 61439-1:2011 with the following
Table 2 – Minimum creepage distances (8.3.3)
Rated Minimum creepage distance
insulation mm
voltage U
i
Pollution degree
1 2 3
b b b
Material group Material group Material group

All material I II IIIa and I II IIIa IIIb
c
groups IIIb
V
32 2,25 2,25 2,25 2,25 2,25 2,25 2,25 2,25
40 2,25 2,25 2,25 2,25 2,25 2,4 2,7 2,7
50 2,25 2,25 2,25 2,25 2,25 2,55 2,85 2,85
63 2,25 2,25 2,25 2,25 2,4 2,7 3 3
80 2,25 2,25 2,25 2,25 2,55 2,85 3,15 3,15
100 2,25 2,25 2,25 2,25 2,7 3 3,3 3,3
125 2,25 2,25 2,25 2,25 2,85 3,15 3,6 3,6
160 2,25 2,25 2,25 2,4 3 3,3 3,75 3,75
200 2,25 2,25 2,25 3 3,75 4,2 4,8 4,8
250 2,25 2,25 2,7 3,75 4,8 5,4 6 6
320 2,25 2,4 3,3 4,8 6 6,75 7,5 7,5
400 2,25 3 4,2 6 7,5 8,4 9,45 9,45
500 2,25 3,75 5,4 7,5 9,45 10,65 12 12
630 2,4 4,8 6,75 9,45 12 13,5 15 15
800 3,6 6 8,4 12 15 16,5 18,75
a
1 000 4,8 7,5 10,65 15 18,75 21 24
1 250 6,3 9,45 13,5 18,75 24 27 30
1 600 8,4 12 16,5 24 30 33 37,5
NOTE 1 The CTI values in footnote c refer to the values obtained in accordance with IEC 60112:2003, method A,
for the insulating material used.
NOTE 2 Values taken from IEC 60664-1, but maintaining a minimum value of 2,25 mm.
NOTE 3 This table reflects a safety multiplication factor to take into account the marine environment.
a
Insulation of material group IIIb is not recommended for use in pollution degree 3 above 630 V.
b
Material groups are classified as follows, according to the range of values of the comparative tracking index
(CTI) (see 3.6.16):
− Material group I 600 ≤ CTI
− Material group II 400 ≤ CTI < 600
− Material group IIIa 175 ≤ CTI < 400
− Material group IIIb 100 ≤ CTI < 175
c
The U to be used in this table is the increased figure as detailed in 5.2.3
i
Table 6 – Temperature rise limits (9.2)
Replace Table 6 of IEC 61439-1:2011 with the following
Table 6 – Temperature rise limits (9.2)
Parts of ASSEMBLIES Temperature-rise
K
a
In accordance with the relevant product standard requirements for the
Built-in components
individual components or, in accordance with the component
f
manufacturer's instructions , taking into consideration the temperature in
the AS
...