IEC 60092-101:2018

IEC 60092-101 ®
Edition 5.0 2018-10
INTERNATIONAL
STANDARD
Electrical installations in ships –
Part 101: Definitions and general requirements

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IEC 60092-101 ®
Edition 5.0 2018-10
INTERNATIONAL
STANDARD
Electrical installations in ships –

Part 101: Definitions and general requirements

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 01.040.47; 47.020.60 ISBN 978-2-8322-6079-1

– 2 – IEC 60092-101:2018 © IEC 2018
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references. 7
3 Terms and definitions . 7
4 General requirements and conditions . 13
4.1 General . 13
4.2 Applicability of the IEC 60092 series to AC and DC . 13
4.3 Acceptance of substitutes or alternatives . 13
4.4 Provisions for maximum load . 13
4.5 Additions and alterations . 13
4.6 Environmental conditions . 13
4.6.1 General . 13
4.6.2 Mandatory condition limits . 14
4.6.3 Design parameters . 14
4.7 Materials . 15
4.8 Power supply system characteristics . 16
4.8.1 General . 16
4.8.2 AC distribution systems . 16
4.8.3 DC distribution systems . 17
4.9 Electrical equipment for hazardous areas . 17
4.10 Precautions necessary when electrical fittings, cables, etc., are attached to
structures of conductive materials with different galvanic potential . 18
4.11 Clearance and creepage distances . 18
4.12 Insulation . 18
4.13 Maintenance and inspection . 18
4.14 Degrees of protection of enclosures . 18
4.15 Cable entries . 18
4.16 Precautions against vibration and mechanical shock . 18
4.17 Position in ship . 19
4.18 Mechanical protection . 19
4.19 Protection from water, steam and oil . 19
4.20 Protection against electrical shock . 19
4.21 Axes of rotation . 19
4.22 Magnetic compasses . 20
4.23 Environmental impact . 20
Annex A (informative) Guidance on environmental conditions . 21
Bibliography . 31

Figure A.1 – Model shock response spectra (first-order maximum shock response
spectra) . 30

Table 1 – Condition limits . 14
Table 2 – Design parameters – Angular deviation and motion . 15
Table 3 – Design parameters – Vibration . 15

Table A.1 – Survey of environmental conditions related to locations . 22
Table A.2 – Environmental condition guidance – Climatic conditions . 23
Table A.3 – Environmental conditions guidance – Biological conditions . 27
Table A.4 – Environmental conditions guidance – Conditions dependent on chemically
and mechanically active substances . 28
Table A.5 – Environmental condition guidance – Mechanical conditions . 29

– 4 – IEC 60092-101:2018 © IEC 2018
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRICAL INSTALLATIONS IN SHIPS –

Part 101: Definitions and general requirements

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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2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
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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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patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60092-101 has been prepared by IEC technical committee 18:
Electrical installations of ships and of mobile and fixed offshore units.
This fifth edition cancels and replaces the fourth edition published in 1994 and Amendment
1:1995. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) the applicability of the standard has been changed to 1 000 V AC and 1 500 V DC:
b) the table for design temperature has been simplified;
c) the clause regarding power supply system characteristics has been rewritten;
d) information regarding pollution degree has been added in the clause regarding clearance
and creepage distances;
e) a clause regarding environmental impact has been added;

f) the clause regarding classification test for materials has been deleted;
g) the annex regarding flame-retardant test for cables has been deleted;
h) the annex regarding test on bunched wires or cables under fire conditions has been
deleted.
The text of this standard is based on the following documents:
FDIS Report on voting
18/1617/FDIS 18/1631/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 publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
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 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.
A bilingual version of this publication may be issued at a later date.

– 6 – IEC 60092-101:2018 © IEC 2018
INTRODUCTION
The IEC 60092 series includes 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 be prepared and a statement of practice for use by ship-owners, shipbuilders and
appropriate organizations.
ELECTRICAL INSTALLATIONS IN SHIPS –

Part 101: Definitions and general requirements

1 Scope
This part of IEC 60092 is applicable to electrical installations for use in ships.
The definitions and general requirements given in this part are applicable, unless otherwise
indicated, to other parts of the IEC 60092 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 60034-30-1, Rotating electrical machines – Part 30-1: Efficiency classes of line operated
AC motors (IE code)
IEC 60079 (all parts), Explosive atmosphere
IEC 60092-201, Electrical installations in ships – Part 201: System design – General
IEC 60092-305, Electrical installations in ships – Part 305: Equipment – Accumulator
(storage) batteries
IEC 60092-504:2016, Electrical installations in ships – Part 504: Automation, control and
instrumentation
IEC 60529, Degrees of protection provided by enclosures (IP Code)
IEC 60533, Electrical and electronic installations in ships – Electromagnetic compatibility
(EMC) – Ships with a metallic hull
IEC 60664-1, Insulation coordination for equipment within low-voltage systems – Part 1:
Principles, requirements and tests
IEC 60695-11-5, Fire hazard testing – Part 11-5: Test flames – Needle-flame test method –
Apparatus, confirmatory test arrangement and guidance
IEC 61439-1:2011, Low-voltage switchgear and controlgear assemblies – Part 1: General
rules
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:
– 8 – IEC 60092-101:2018 © IEC 2018
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
NOTE Definitions included in this part are those having general application in IEC 60092. Definitions applying to
particular apparatus or equipment which are only included within a single part of IEC 60092 are separately defined
in that part only.
3.1
appropriate authority
governmental body and/or classification society whose rules a ship is required to comply with
3.2
ocean-going ship
ship not exclusively employed in the navigation of rivers or inland waters
3.3
essential services
services essential for the navigation, propulsion, steering or manoeuvring of the ship, or for
the safety of human life, or for special characteristics of the ship (for example special
services)
3.4
accessory
device, other than a luminaire (see IEC 60092-306), associated with the wiring and current-
using appliances of an installation
EXAMPLE Switch, fuse, plug, socket-outlet, lampholder or junction box.
3.5
bond
connection of non-current-carrying parts to ensure continuity of electrical connection, or to
equalize the potential between parts comprising, for example, the armour or lead sheath of
adjacent length of cable, the bulkhead, etc.
EXAMPLE Bulkhead and cables in a radio-receiving room.
3.6
earth
general mass of the metal hull of the ship
Note 1 to entry: In the USA, "ground" is used instead of "earth".
3.7
earthed
connected to the general mass of the hull of the ship in such a manner as will ensure at all
times an immediate discharge of electrical energy without danger
Note 1 to entry: A conductor is said to be "solidly earthed" when it is electrically connected to the hull without a
fuse-link, switch, circuit-breaker, resistor, or impedance, in the earth connection.
Note 2 to entry: In the USA. "grounded" is used instead of "earthed".
3.8
basic insulation
insulation of hazardous-live-parts which provides basic protection
Note 1 to entry: This concept does not apply to insulation used exclusively for functional purposes
[SOURCE: IEC 60050-195:1998, 195-06-06]

3.9
supplementary insulation
independent insulation applied in addition to basic insulation, for fault protection
[SOURCE: IEC 60050-195:1998, 195-06-07]
3.10
double insulation
insulation comprising both basic insulation and supplementary insulation
[SOURCE: IEC 60050-195:1998, 195-06-08]
3.11
reinforced insulation
insulation of hazardous-live-parts which provides a degree of protection against electric shock
equivalent to double insulation
Note 1 to entry: Reinforced insulation may comprise several layers which cannot be tested singly as basic
insulation or supplementary insulation
[SOURCE: IEC 60050-195:1998, 195-06-09]
3.12
live
qualifies a conductive part intended to be energized in normal operation
Note 1 to entry: A live part may be temporarily dead when it is not energized. A neutral conductor is considered
as live but earthing conductors are not.
[SOURCE: IEC 60050-151:2001, 151-15-60]
3.13
maritime distribution board
switchgear and controlgear 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 has been replaced by distribution board.
3.14
final subcircuit
that portion of a wiring system extending beyond the final overcurrent protective device of a
board
3.15
point
any termination of the fixed wiring intended for the attachment of a luminaire or for
connecting to the supply a current-using appliance
3.16
extra low voltage
voltage not exceeding the relevant voltage limit of extra low voltage (ELV)-band specified in
IEC 61140
Note 1 to entry: The voltage band for ELV in IEC 61140 is equal or less than 50 V AC and equal and less than
120 V DC.
[SOURCE: IEC 60050-826:2004, 826-12-30; modified]

– 10 – IEC 60092-101:2018 © IEC 2018
3.17
materials
3.17.1
arc-resistant material
material is arc-resistant when it is not excessively damaged by the action of the repeated arcs
that may occur at its surface under actual duty conditions
3.17.2
flame retardant material
material whereby flaming combustion is slowed, terminated or prevented
3.17.3
fire resistant material
material able to withstand fire or give protection from it for a period of time
3.17.4
non-combustible material
material not capable of undergoing combustion under specified conditions
Note 1 to entry: A material is classified as being non-combustible even if it is capable of combustion, provided
that its heat of combustion is less than a defined amount.
3.18
spaces
3.18.1
accomodation spaces
spaces used for public spaces, corridors, lavatories, cabins, offices, crew quarters, barber
shops, isolated pantries and lockers, and similar spaces
3.18.2
cargo spaces
spaces used for cargo (including liquid cargo tanks) and trunks to such spaces
3.18.3
hazardous area
area in which an explosive atmosphere is present, or may be expected to be present, in
quantities such as to require special precautions for the construction, installation and use of
electrical equipment
Note 1 to entry: IEC 60079-10-1 specifies requirements to classification of hazardous areas in potential explosive
gas atmospheres (see also IEC 60050-426:2008, 426-03-03, 426-03-04 and 426-03-05).
Note 2 to entry: For tankers, see IEC 60092-502.
Note 3 to entry: Hazardous spaces are also referred to as dangerous spaces.
[SOURCE: IEC 60050-426:2008, 426-03-01; modified]
3.18.4
machinery spaces
all spaces containing propelling machinery, boilers, oil fuel units, steam and internal
combustion engines, generators and major electrical machinery, oil filling stations,
refrigerating, stabilizing, ventilation and air-conditioning machinery, and similar spaces; and
trunks to such spaces
3.18.5
public spaces
portions of the accommodation used for halls, dining-rooms, lounges, and similar permanently
enclosed spaces
3.18.6
service spaces
spaces used for galleys, main pantries, stores (except isolated pantries and lockers), mail and
specie rooms, workshops other than those forming part of machinery spaces, and similar
spaces and trunks to such spaces
3.18.7
main vertical zones
sections into which the hull, superstructure and deck houses are divided by fire-resisting
bulkheads and decks.
Note 1 to entry: The mean length of these on any deck does not in general exceed 40 m.
3.18.8
control stations
spaces in which the ship's radio or main navigating equipment or the emergency source of
power is located, or where the fire recording or fire control equipment is centralized
3.18.9
degree of protection of enclosure
IP (abbreviation)
classification according to IEC 60529 preceded by the symbol IP applied to the enclosure of
electrical apparatus to provide:
– protection of persons against contact with, or approach to, live parts and against contact
with moving parts inside the enclosure,
– protection of the electrical apparatus against ingress of solid foreign objects, and
– where indicated by the classification, protection of the electrical apparatus against harmful
ingress of water
[SOURCE: IEC 60050-426:2008, 426-04-02, modified]
3.19
voltage
3.19.1
voltage tolerance
maximum departure from nominal user voltage during normal operating conditions, excluding
transient and cyclic voltage variations
Note 1 to entry: Voltage tolerance is a steady state tolerance and includes voltage drop in cables and voltage
regulator characteristics. It also includes variations due to environmental conditions.
3.19.2
voltage unbalance tolerance
difference between the highest and lowest phase to phase voltage
3.19.3
voltage cyclic variation deviation
periodic voltage deviation (max. to min. RMS values) of the nominal voltage, such as might be
caused by regularly repeated loading
± (U −U )×100
max min
SEE Voltage cyclic variation = %
2U
nominal
3.19.4
voltage transient
sudden change in voltage (excluding spikes) which goes outside the nominal voltage
tolerance limits and returns to and remains inside these limits within a specified recovery time
after the initiation of the disturbance

– 12 – IEC 60092-101:2018 © IEC 2018
Note 1 to entry: The recovery time is measured in seconds.
3.20
waveform
3.20.1
total harmonic distortion
THD
ratio of the RMS value of the sum of all the harmonic components up to a specified order
(recommended notation "H") to the RMS value of the fundamental component
h=H
(Q)
h
THD= ∑
h=2 (Q)
where
Q represents either current or voltage;
Q is the RMS value of the fundamental component;
h is the harmonic order;
Q is the RMS value of the harmonic component of order h;
h
H is 50 for the purpose of the compatibility levels in this document
Note 1 to entry: THD takes account of harmonics only. For any case where interharmonics are included, reference
is made to A.3.1 of IEC 61000-2-4:2002.
[SOURCE: IEC 61000-2-4:2002, 3.2.7, modified – The definition has been rephrased and the
expression "of IEC 61000-2-4:2002" has been added in the note to entry.]
3.20.2
single harmonic content
ratio of the effective RMS value of that harmonic to the RMS value of the fundamental
expressed in per cent
3.21
frequency
3.21.1
frequency tolerance
maximum deviation from nominal frequency during normal operation conditions excluding
transient and cyclic frequency variations
Note 1 to entry: Frequency tolerance is a steady state tolerance and includes variations caused by loads and
governor characteristics. It also includes variations due to environmental conditions.
3.21.2
frequency cyclic variation
periodic deviation in frequency during normal operation such as might be caused by regularly
repeated loading
± (f − f )×100
max min
Frequency cyclic variation = %
2 f
nominal
3.21.3
frequency transient
sudden change in frequency which goes outside the frequency tolerance limits and returns to
and remains inside these limits within a specified recovery time after the initiation of the
disturbance
Note 1 to entry: The recovery time is measured in seconds.

3.22
time
3.22.1
voltage transient recovery time
time elapsed from exceeding the normal tolerance until the voltage recovers and remains
within the normal tolerance limits
3.22.2
frequency transient recovery time
time elapsed from exceeding the normal tolerance until the frequency recovers and remains
within the frequency tolerance limits
4 General requirements and conditions
4.1 General
This clause contains conditions and requirements which are common to all apparatus and in-
stallations.
NOTE Attention is drawn to the requirements of the International convention for the safety of life at sea (SOLAS).
4.2 Applicability of the IEC 60092 series to AC and DC
Except where a specific statement is made to the contrary, all parts of the IEC 60092 series
are equally applicable to AC and DC installations. For voltages above 1 000 V AC and
1 500 V DC additional requirements will be found in IEC 60092-503.
4.3 Acceptance of substitutes or alternatives
Where, in the IEC 60092 series, any special type of apparatus, construction or arrangement is
specified, the use of any other apparatus, construction or arrangement is permissible,
provided it is demonstrated to give an equivalent level of safety, performance and reliability.
4.4 Provisions for maximum load
All conductors, switchgear and accessories shall be of such size as to be capable of carrying,
without their respective ratings being exceeded, the current which can normally flow through
them. They shall be capable of carrying anticipated overloads and transient currents, for
example the starting currents of motors, without damage or reaching abnormal temperatures.
4.5 Additions and alterations
An addition or alteration, temporary or permanent, shall not be made to an existing installation
until it has been definitely ascertained that the ratings and the condition of existing
accessories, conductors, switchgear, etc., affected are adequate for the new situation.
Special attention is drawn to those factors affecting the existing system design such as
current-carrying capacity, short-circuit level, voltage drop, harmonics, stability and proper
discrimination of the protective devices.
Any addition or alteration, temporary or permanent, made to an existing installation shall be
properly documented and the documentation retained for future reference.
4.6 Environmental conditions
4.6.1 General
Electrical equipment shall operate satisfactorily under various anticipated environmental
conditions.
– 14 – IEC 60092-101:2018 © IEC 2018
Environmental conditions are influenced by a number of variables such as climatic conditions,
biological conditions, conditions dependent upon chemically and mechanically active
substances, mechanical conditions, location in vessels, operational patterns and transient
conditions. These will generally be defined by the vessels owner or operator.
Further guidance may be found in Annex A, based on IEC 60721-3-6.
4.6.2 Mandatory condition limits
Certain environmental condition parameters and associated severity values are specified by
appropriate authorities and represent limits, consequently constituting a basis for design. The
requirements generally applicable are given in Tables 1 to 5.
Table 1 – Condition limits
Angular deviation and motion
Angular deviation about for-and-aft axis (list)
General conditions ± 15°
a
± 22° 30'
Emergency conditions
Static condition
Angular deviation about athwartship axis (trim)
a
± 10°
Emergency conditions
Rotation about fore-and-aft ± 22° 30'
b
axis (rolling)
Dynamic condition
Rotation about athwartship ± 7° 30'
b
axis (pitching)
Low air temperature
Emergency generator sets Min. 0 °C
a
The vessel in any combination of angles within these limits.
b
These motions may occur simultaneously.

4.6.3 Design parameters
4.6.3.1 General
Design parameters based on environmental conditions applicable to certain types of
equipment have been established in other parts of the IEC 60092 series, and are described in
4.6.3.2 to 4.6.3.5.
4.6.3.2 Temperature
In other parts of the IEC 60092 series, where no "high air temperature" has been specified as
a design parameter for equipment, an average value over a 24 h period of 40 °C with a
maximum value of 45 °C shall apply.
Where equipment is designed to operate with temperatures higher or lower than those stated,
permissible temperature rises may be reduced or increased accordingly. All stated unit values
are to be considered as the average ambient temperature over a 24 h period and a maximum
value is to be defined.
In other parts of the IEC 60092 series, where no "low air temperature" has been specified as
a design parameter for equipment, a minimum temperature of 5 °C in general and –25 °C for
open decks shall be applied.
4.6.3.3 Humidity
The design parameters for relative humidity are 95 % at 45 °C ambient temperature, unless
otherwise specified in other parts of the 60092 series.
NOTE Note the additional damp heat test in IEC 60092-504.
4.6.3.4 Angular deviation and motion
The design parameters for angular deviation and motion are given in Table 2.
Table 2 – Design parameters – Angular deviation and motion
Unit
Parameters Type of equipment
value
Standard
Static condition – all directions Angle
IEC 60092-305:1980 40° Accumulators (storage batteries)
IEC 60092-504 22,5° Control and instrumentation
Dynamic condition– all directions Angle Frequency
Hz
IEC 60092-504 22,5° 0,1 Control and instrumentation

NOTE IEC 60092-305 applies to accumulator batteries in general. However, it does not address other types than
lead-acid and nickel-alkaline. Other battery technologies are under consideration.
4.6.3.5 Vibration
The design parameters for vibration are given in Table 3.
Table 3 – Design parameters – Vibration
Parameters Unit Type of equipment
value
Standard Table
a a
Vibration Frequency
Displacement Acceleration
Hz
mm g
IEC 60092-504:2016 Table 1, 10 1,0 2-13,2
Control and
instrumentation
0,7 13,2-100
IEC 60092-504:2016 Table 1,10 1,6 2-25 Control and
instrumentation, special
4 25-100
location
a
Amplitude values.
4.7 Materials
In general, all electrical equipment shall be constructed of durable, flame-retardant material,
which is not detrimentally affected due to moisture, the atmosphere and the temperatures to
which they are likely to be exposed.
The flame-retardant material shall comply with the needle flame test of IEC 60695-11-5
according to the following specifications.
The flame shall be applied:
– 16 – IEC 60092-101:2018 © IEC 2018
– 5 times for 15 s each time. The interval between each application shall be 15 s, or
– 1 time for 30 s;
The layer surrounding or situated below the test specimen shall be of wrapped tissue paper.
The dripping height shall be 200 mm ± 5 mm.
Additional acceptance criteria to those specified in IEC 60695-11-5: the burnt out or damaged
part of the specimen shall not be more than 60 mm long.
NOTE 1 The additional test specifications and test criteria are given to align with IACS requirements.
NOTE 2 For further information regarding environmental conditions, refer to IEC 60721-3-6.
4.8 Power supply system characteristics
4.8.1 General
Unless otherwise stated in other parts of the IEC 60092 series, equipment shall function when
supplied from general distribution systems with due regard to voltage and frequency
variations, harmonic distortion and conducted disturbances, measured at the terminals of the
equipment. The characteristics of general distribution systems are given in 4.8.2 and 4.8.3.
For systems where semiconductors are connected having a total system rating which is a
significant portion of the total system rating, it may not be feasible to suppress the harmonics.
Consideration should be given to take appropriate measures to attenuate these effects of the
distribution system so that safe operation is assured. Care should be taken in selecting
consumers supplied from an electric power supply system with a higher harmonic content
than specified in this clause and it should be ensured that the equipment is appropriate for the
harmonic content that will be encountered.
Electrical equipment which requires a higher quality power supply may need additional
provisions to be made locally. Where additional equipment is fitted to achieve this higher
quality power supply it may be required to be duplicated and segregated to the same degree
as the electrical equipment it supplies.
Special attention should be paid to the installation of electrical equipment which may
influence the quality of power supply on local basis or react with any harmonics present on
the general distribution system.
Variable frequency/voltage systems may be admissible provided safe operation of the system
is assured and that equipment is suitably rated for the expected variations.
4.8.2 AC distribution systems
4.8.2.1 Voltage characteristics
Tolerances are expressed in a percentage of the nominal voltage.
Voltage are root mean square (RMS) unless otherwise stated.
Voltage tolerance (continuous) . +6 % –10 %
Voltage unbalance tolerance including phase voltage unbalance
as a result of unbalance of load according to IEC 60092-201 . 7 %
Phase to phase voltage unbalance (continuous) . 3 %
Cyclic voltage variation (continuous) . 2 %
Voltage transients:
– transients (slow) e.g. due to load variations tolerance
(deviation from nominal voltage) . +20 % ‒20 %

– voltage transients recovery time . maximum 1,5 s
The sum of voltage excursions at any point on the system (tolerances and transient) from
nominal voltage should not exceed 20 %.
– fast transients and surges e.g. spikes caused by switching shall not exceed the levels
given in IEC 61439-1:2011, Table G.1, and the levels specified in IEC 60533 for AC power
ports
– Overvoltage category . III
For voltage values, see IEC 61439-1:2011, Table G.1.
NOTE Values for AC systems with rated voltage above 1 000 V are not given in IEC 61439-1.
For voltage harmonic distortion, acceptance limits shall correspond to IEC 61000-2-4,
Class 2. In addition, no single harmonic shall exceed 5 % and the THD shall not exceed 8 %.
Other values may be considered subject to approval of the appropriate authority.
Some equipment may require IEC 61000-2-4, Class 1, i.e. no single harmonic shall exceed
3 % and the THD shall not exceed 5 %.
4.8.2.2 Frequency characteristics
Tolerances are expressed in a percentage of the nominal frequency.
Frequency tolerance (continuous) . +5 % –5 %
Frequency cyclic variation tolerance (continuous) . 0,5 %
Frequency transients tolerance . +10 % –10 %
Frequency transients recovery time . maximum 5 s
The sum of frequency excursions at any point on the system (tolerances and transient) from
nominal frequency should not exceed 12,5 %.
4.8.3 DC distribution systems
Tolerances are expressed in a percentage of the nominal voltage.
Voltage tolerance (continuous) . +30 % –25 %
Voltage cyclic variation deviation. 5 %
Voltage ripple (AC RMS over steady DC voltage) . 10 %
Overvoltage ,category . III
Lower variations may be agreed by owners and builders where the technology permits
DC Converters may permit closer control of voltages.
NOTE 1 For voltage values, See IEC 61439-1:2011, Table G.1.
NOTE 2 Values for DC systems with rated voltage above 1 000 V are not given in IEC 61439-1.
4.9 Electrical equipment for hazardous areas
When an equipment is required to be suitable for use in hazardous areas, it shall comply with
the requirements of the IEC 60079 series.

– 18 – IEC 60092-101:2018 © IEC 2018
Such equipment shall be constructed and tested in accordance with the requirements of the
IEC 60079 series and be certified as fit for purpose for the actual ambient temperature and
other environmental conditions, to the satisfaction of the appropriate authority.
NOTE Certification is done by a nationally accredited testing Institution.
Unless otherwise indicated in the IEC 60092 series, all such apparatus may be installed in
accordance with the relevant clauses contained in IEC 60079-14.
4.10 Precautions necessary when electrical fittings, cables, etc., are attached to
structures of conductive materials with different galvanic potential
4.10.1 If electrical fittings, not of aluminium, are attached to aluminium, suitable means shall
be taken to prevent galvanic corrosion.
4.10.2 During both the selection and installation of electrical equipment special
considerations shall be given to avoid galvanic corrosion.
4.11 Clearance and creepage distances
The distances between live parts of different potential and between live parts and the cases of
other earthed metal, whether across surfaces or in air, shall be adequate for the working
voltage, having regard to the nature of the insulating material and the conditions of service.
Unless otherwise specified a pollution degree 3 according to IEC 60664-1 shall be assumed.
4.12 Insulation
Insulating materials and insulated windings shall be resistant to moisture, sea air and oil
vapour, unless special precautions are taken to protect insulants against such agents.
Insulating materials in direct contact with conductors, such as busbar supports, should have
sufficient resistance against tracking. It is recommended that the comparative tracking index
of such materials be not less than 175 V when determined according to IEC 60112.
4.13 Maintenance and inspection
Equipment shall be so designed and installed as to permit its being maintained and inspected
in accordance with the manufacturer’s recommendations.
4.14 Degrees of protection of enclosures
Enclosures referred to in the various parts of the IEC 60092 series are those as defined in
IEC 60529 and shall have the appropriate degree of protection for their designated location on
the vessel as specified in the relevant part of the IEC 60092 series. The designation to
indicate the degrees of protection consists of the characteristic letters IP followed by two
numerals (the "characteristic numerals") indicating conformity with the conditions stated in
IEC 60529.
4.15 Cable entries
Cable glands or bushings, or fittings for screwed conduits, shall be suitable for the intended
cables and shall facilitate the cable entrance into the equipment. All entries shall maintain the
degree of protection provided by the enclosure of the associated equipment.
4.16 Precautions against vibration and mechanical shock
Machines and apparatus shall be unaffected by vibration and shock likely to arise under
normal service. Connections shall be secured against becoming loose due to vibration.

4.17 Position in ship
4.17.1 Electrical equipment is to be located in compartments which are suitably constructed
and, if necessary, ventilated.
4.17.2 Electrical equipment shall not be installed where flammab
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