IEC 61892-1:2015

IEC 61892-1 ®
Edition 3.0 2015-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Mobile and fixed offshore units – Electrical installations –
Part 1: General requirements and conditions

Unités mobiles et fixes en mer – Installations électriques –
Partie 1: Exigences générales et conditions

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IEC 61892-1 ®
Edition 3.0 2015-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Mobile and fixed offshore units – Electrical installations –

Part 1: General requirements and conditions

Unités mobiles et fixes en mer – Installations électriques –

Partie 1: Exigences générales et conditions

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 47.020.60 ISBN 978-2-8322-2784-8

– 2 – IEC 61892-1:2015  IEC 2015

CONTENTS
FOREWORD . 4

INTRODUCTION . 6

1 Scope . 7

2 Normative references . 7

3 Terms and definitions. 8

4 General requirements and conditions . 11

4.1 General . 11
4.2 Acceptance of substitutes or alternatives . 12
4.3 Additions and alterations . 12
4.4 Environmental conditions. 12
4.4.1 General . 12
4.4.2 Design parameters . 12
4.5 Materials . 13
4.6 Power supply system characteristics. 14
4.6.1 General . 14
4.6.2 AC distribution systems . 14
4.6.3 DC distribution systems . 16
4.7 Manual disconnection . 17
4.8 Electrical apparatus for explosive gas atmospheres . 17
4.9 Clearance and creepage distances . 17
4.10 Insulation . 17
4.11 Maintenance and inspection . 17
4.12 Cable entries . 18
4.13 Precautions against vibration and mechanical shock . 18
4.14 Location of electrical equipment in units . 18
4.15 Mechanical protection . 18
4.16 Protection from heat, water, steam and oil . 18
4.17 Protection against electrical shock . 19
4.18 Enclosures . 19
4.19 Environmental impact . 19
Annex A (informative) Degree of protection . 20
A.1 Definitions of numerals in the IP code . 20

Annex B (informative) Cold climate precautions . 22
Annex C (informative) Specification of surface treatment and protective painting system . 23
C.1 Objectives . 23
C.2 General and specification . 23
C.2.1 General . 23
C.2.2 Atmospheric corrosivity categories for protective painting systems . 23
C.2.3 Durability performance of a protective painting system . 24
Annex D (informative) DC distribution systems . 26
D.1 DC distribution systems . 26
Bibliography . 27

Figure D.1 – Typical configuration of DC distribution system . 26

Table 1 – Operational design parameters – Ambient temperature . 13

Table 2 – Design parameters – Relative humidity . 13

Table 3 – Voltage characteristics . 15

Table 4 –Frequency characteristics . 16

Table 5 –Tolerances for DC system . 16

Table 6 – Fast transients . 17

Table A.1 – Degrees of protection against foreign objects indicated by the first

characteristic numeral . 20

Table A.2 – Degrees of protection against water indicated by the second characteristic

numeral . 21
Table C.1 – Description of typical atmospheric environments related to the estimation of
corrosivity categories . 24

– 4 – IEC 61892-1:2015  IEC 2015

INTERNATIONAL ELECTROTECHNICAL COMMISSION

_____________
MOBILE AND FIXED OFFSHORE UNITS –

ELECTRICAL INSTALLATIONS –
Part 1: General requirements and conditions

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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6) All users should ensure that they have the latest edition of this publication.
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of

patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61892-1 has been prepared by IEC technical committee 18:
Electrical installations of ships and of mobile and fixed offshore units.
This third edition cancels and replaces the second edition published in 2010. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition.
a) The general requirement to harmonic distortion has been changed from IEC 61000-2-4
Class 2 to Class 1.
b) The voltage tolerance for a DC system has been changed from ±10 % to +10 %, −15 %.
c) Annex C (informative) regarding specification of surface treatment and protective painting
system has been added.
The text of this standard based on the following documents:

CDV Report on voting
18/1385/CDV 18/1449/RVC
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 of the IEC 61892 series can be found, under the general title Mobile and fixed
offshore units – Electrical installations, 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 website 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.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this document using a colour printer.

– 6 – IEC 61892-1:2015  IEC 2015

INTRODUCTION
The IEC 61892 series of International Standards is intended to enable safety in the design,

selection, installation, maintenance and use of electrical equipment for the generation, storage,

distribution and utilization of electrical energy for all purposes in offshore units which are used

for the purpose of exploration or exploitation of petroleum resources.

This part of the IEC 61892 incorporates and co-ordinates, as far as possible, existing rules and

forms a code of interpretation, where applicable, of the requirements of the International

Maritime Organization, a guide for future regulations which may be prepared and a statement

of practice for offshore unit owners, constructors and appropriate organizations.

This standard is based on equipment and practices which are in current use, but it is not
intended in any way to impede development of new or improved techniques.
The ultimate aim has been to produce a set of International Standards exclusively for the
offshore petroleum industry.
MOBILE AND FIXED OFFSHORE UNITS –

ELECTRICAL INSTALLATIONS –
Part 1: General requirements and conditions

1 Scope
This part of IEC 61892 contains provisions for electrical installations in mobile and fixed
offshore units including pipeline, pumping or 'pigging' stations, compressor stations and
exposed location single buoy moorings, used in the offshore petroleum industry for drilling,
processing and storage purposes.
This International Standard applies to all installations, whether permanent, temporary,
transportable or hand-held, to AC installations up to and including 35 000 V and DC
installations up to and including 1 500 V (AC and DC voltages are nominal values).
This standard does not apply either to fixed equipment for medical purposes or to the electrical
installations of tankers.
NOTE For medical rooms, IEC 60364-7-710 provides more information.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments)
applies.
IEC 60034 (all parts), Rotating electrical machines
IEC 60034-1:2010, Rotating electrical machines – Part 1: Rating and performance
IEC 60079 (all parts), Explosive atmospheres
IEC 60529, Degrees of protection provided by enclosures (IP Code)

IEC 61000-2-4:2002, Electromagnetic compatibility (EMC) – Part 2-4: Environment –
Compatibility levels in industrial plants for low-frequency conducted disturbances
IEC 61140, Protection against electric shock – Common aspects for installation and equipment
IEC 61892-2:2012, Mobile and fixed offshore units – Electrical installations – Part 2: System
design
IEC 61892-5, Mobile and fixed offshore units – Electrical installations – Part 5: Mobile units
IEC 61892-6, Mobile and fixed offshore units – Electrical installations – Part 6: Installation
IEC 61892-7, Mobile and fixed offshore units – Electrical installations – Part 7: Hazardous
areas
International Convention for the Safety of Life at Sea (SOLAS):1974, Consolidated edition 2009

– 8 – IEC 61892-1:2015  IEC 2015

IMO MODU Code, Code for the construction and equipment of mobile offshore drilling units

3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

NOTE The terms and definitions included in this part are those having general application in the IEC 61892 series.
Terms and definitions applying to particular apparatus or equipment are included in the other parts of IEC 61892.

3.1
appropriate authority
governmental body and/or classification society with whose rules a unit is required to comply
3.2
equipment
single apparatus or set of devices or apparatuses, or the set of main devices of an installation,
or all devices necessary to perform a specific task
EXAMPLE Power transformer, measuring equipment.
[SOURCE IEC 60050-151:2001, 151-11-25, modified — The words “the equipment of a
substation” has been removed from the example.]
3.3
apparatus
device or assembly of devices which can be used as an independent unit for specific functions
[SOURCE IEC 60050-151:2001, 151-11-22, modified — The note has been deleted.]
3.4
rooms with a controlled atmosphere
rooms where the temperature and humidity can be controlled within specified limits
3.5
degree of protection of enclosure
IP
numerical 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 (other than smooth rotating shafts and the like) 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
Note 1 to entry: Explanation of the numerals used for classification of degree of protection is given in Tables A.1
and A.2.
[SOURCE IEC 60050-426:2008, 426-04-02, modified — Note 1 to entry has been added.]
3.6
distribution board
assembly containing different types of switchgear and controlgear associated with one or more
outgoing electric circuits fed from one or more incoming electric circuits, together with
terminals for the neutral and protective conductors, if required

[SOURCE IEC 60050-826:2004, 826-16-08, modified — The words “if required” have been

added.]
3.7
earth
ground, US, CA
general mass of the metal structure or hull of the unit

3.8
earthed
connected to the general mass of the metal structure or hull of the unit in such a manner as will

ensure at all times an immediate discharge of electrical energy without danger
3.9
essential services
services essential for the navigation, steering or manoeuvring of the mobile unit, or for the
safety of human life, or for special characteristics of the unit (for example special services)
3.10
frequency
3.10.1
cyclic frequency variation
periodic deviation in frequency during normal operation such as might be caused by regularly
repeated loading
±( f - f ) × 100
max min
%
2 f
nominal
3.10.2
frequency tolerance
maximum departure 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.
3.10.3
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 initiation of the
disturbance (time range: seconds)

3.11
live part
conductor or conductive part intended to be energized in normal operation, including a neutral
conductor, but by convention not a PEN conductor or PEM conductor or PEL conductor
Note 1 to entry: This concept does not necessarily imply a risk of electric shock.
[SOURCE IEC 60050-195:1998, 195-02-19]
3.12
PEN conductor
conductor combining the functions of both a protective earthing conductor and a neutral
conductor
[SOURCE IEC 60050-195:1998, 195-02-12]

– 10 – IEC 61892-1:2015  IEC 2015

3.13
PEM conductor
conductor combining the functions of both a protective earthing conductor and a mid-point

conductor
[SOURCE IEC 60050-195:1998, 195-02-13]

3.14
PEL conductor
conductor combining the functions of both a protective earthing conductor and a line conductor

[SOURCE IEC 60050-195:1998, 195-02-14]
3.15
petroleum
complex mixture of hydrocarbons that occurs in the earth in liquid or gaseous forms
3.16
point
any termination of the fixed wiring intended for the attachment of a luminaire or for connecting
to the supply of a current-using appliance
3.17
voltages
3.17.1
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.
3.17.2
voltage unbalance tolerance
difference between the highest and lowest phase to phase voltage
3.17.3
cyclic voltage variation
periodic voltage deviation (max. to min. r.m.s. values) of the nominal voltage, such as might be
caused by regularly repeated loading

±(U − U )× 100
max min
%
2 U
nominal
3.17.4
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 (time range: seconds)
3.18
recovery time
3.18.1
voltage transient recovery time
time elapsed from exceeding the normal voltage tolerance until the voltage recovers and
remains within the normal tolerance limits

3.18.2
frequency transient recovery time

time elapsed from exceeding the normal frequency tolerance until the frequency recovers and

remains within the frequency tolerance limits

3.19
waveform
3.19.1
total harmonic distortion
THD
ratio of the r.m.s. value of the sum of all the harmonic components up to a specified order

(recommended notation “H”) to the r.m.s. value of the fundamental component
h=H
(Q)
h
THD= ∑
h=2
(Q)
where
Q represents either current or voltage;
Q is the r.m.s. value of the fundamental component;
h is the harmonic order;
Q is the r.m.s. value of the harmonic component of order h;
h
H is 50 for the purpose of the compatibility levels in this standard
Note 1 to entry: THD takes account of harmonics only. For the case where interharmonics are to be included,
reference is made to A.3.1 of IEC 61000-2-4:2002.
Note 2 to entry: This note applies to the French language only.
[SOURCE IEC 61000-2-4:2002, 3.2.7, modified — Note 1 to entry is modified.]
3.19.2
single harmonic content
ratio of the effective r.m.s. value of the harmonic to the r.m.s. value of the fundamental
expressed in per cent
4 General requirements and conditions
4.1 General
This clause contains conditions and requirements which are common to all equipment and
installations in the IEC 61892 series.
Electrical installations in units shall be such that:
– essential services will be maintained under various emergency conditions;
– the safety of crew, contractors, visitors and unit will be ensured;
– the requirements with respect to safety in this standard are considered;
– the requirements of the International Convention for the Safety of Life at Sea (SOLAS) are
met as far as applicable;
– the requirements of the IMO MODU Code are met as far as applicable.
For floating and mobile units, all machinery and equipment shall operate satisfactorily under
the static and dynamic inclination limits according to IEC 61892-5.

– 12 – IEC 61892-1:2015  IEC 2015

The appropriate authority may have additional requirements which have to be complied with.

NOTE Emergency conditions are normally defined in the safety assessment of the installation.

4.2 Acceptance of substitutes or alternatives

Where in the IEC 61892 series any special type of equipment, construction, or arrangement is
specified, the use of any other equipment, construction or arrangement is admissible, provided

it is not less effective and reliable.

4.3 Additions and alterations
An addition or alteration, temporary or permanent, shall not be made to an existing installation
until it has been 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 discri-
mination of the protective devices.
4.4 Environmental conditions
4.4.1 General
Electrical equipment shall operate satisfactorily under various environmental conditions.
Environmental conditions are characterised by a number of variables:
– one set including mainly climatic conditions, biological conditions, conditions dependent
upon chemically and mechanically active substances and mechanical conditions;
– another set dependent mainly upon locations in unit, operational patterns and transient
conditions.
NOTE For further information regarding environmental conditions in conjunction with some selected locations,
operational patterns and transient conditions which are considered to be generally representative,
see IEC 60721-3-6.
4.4.2 Design parameters
4.4.2.1 General
Design parameters based on environmental conditions applicable to certain types of equipment
may be determined according to location. Where no data is available, Table 1 and Table 2 give
recommended values.
In certain areas, e.g. arctic areas, lower temperatures than those given in the tables have to be
taken into consideration. In certain areas, also a higher temperature than given in the tables
has to be taken into consideration.
4.4.2.2 Temperature
For a specific project, the project documentation may give specific information regarding
ambient temperature. In absence of such information, the following may be used:
In other parts of the IEC 61892 series, where no "high air temperature" has been specified as a
design parameter for equipment, a value of 45 ºC shall apply.
Where equipment is designed to operate with temperatures higher or lower than those stated in
Table 1, permissible temperature rises may be reduced or increased accordingly.

Table 1 – Operational design parameters – Ambient temperature

Type of equipment Value
º
C
High air temperature
Cables 45
Generators and motors 50
Switchgear 45
Transformers 45
Control and instrumentation 55
Other electrical equipment 45
Low air temperature
Control and instrumentation 5 (general)
Control and instrumentation −25 (open deck)
High water temperature
Generators and motors 35
NOTE The lower design temperature will normally be specified in the product
standard.
For batteries, see IEC 61892-6.
Sea water temperature is max 32 °C.
4.4.2.3 Relative humidity
Design values for relative humidity are given in Table 2.
Table 2 – Design parameters – Relative humidity
Value
o
% C
95 Up to 45
70 Above 45
4.5 Materials
In general, all electrical equipment shall be constructed of durable, flame-retardant, moisture-
resistant materials, which are not subject to deterioration in the atmosphere and at the
temperatures to which they are likely to be exposed.
Equipment enclosures located outdoor, in naturally ventilated and wash down areas shall be
made of proven seawater resistant materials.
NOTE 1 Examples of such material are seawater resistant aluminium, stainless steel or UV resistant plastic
material.
Suitable means shall be taken to prevent galvanic corrosion when securing dissimilar metals,
for example aluminium to the steel structure or hull of a unit.
NOTE 2 For further information regarding environmental conditions; refer to IEC 60721-3-6.

– 14 – IEC 61892-1:2015  IEC 2015

4.6 Power supply system characteristics

4.6.1 General
Unless otherwise stated in other parts of this standard, the equipment shall function when
supplied from general distribution systems with due regard to voltage and frequency variations,
harmonic distortion and conducted disturbances. The characteristics of general distribution

systems are given in the following subclauses.

Where the power supply is obtained from the shore, due regard should be paid to the effect

that the quality of the supply, if different from that specified in this clause, may have on the

performance of equipment.
For systems where semiconductors are connected having a total rating which is a significant
portion of the total system rating, it may be feasible to suppress the harmonics. Consideration
should be given to taking 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.
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 a 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 equipment is suitably rated for the expected variations.
4.6.2 AC distribution systems
4.6.2.1 General
The voltages referred to in 4.6.2.2 are measured at the point where the equipment is installed.
Electric motors are normally designed for a combination of voltage and frequency variations
which is less than the combined limits given in this clause. For combined voltage and
frequency variations for electric motors, reference is made to IEC 60034-1.

4.6.2.2 Voltage characteristics
Requirements to voltage characteristics are given in Table 3. Tolerances are expressed in a
percentage of the nominal voltage.

Table 3 – Voltage characteristics

Voltage characteristics Value
Voltage tolerance (continuous)
+6
%
−10
Voltage unbalance tolerance including phase voltage 7 %
unbalance as a result of unbalance of load according to

IEC 61892-2
Cyclic voltage variation (continuous). 2 %

Voltage transients:
• slow transients e.g. due to load variations tolerance
+20
%
(deviation from nominal voltage)
−20
• voltage transients recovery time maximum 1,5 s
Voltages are root mean square (r.m.s.) unless otherwise stated.

Where three-phase AC motors conforming to the IEC 60034 series are connected, then the
system negative sequence component shall not exceed 1 % of the positive sequence
component over a long period, or 1,5 % for a short period not exceeding a few minutes, and a
zero sequence component not exceeding 1 % of the positive sequence component.
The transient voltage at the point where equipment is installed can be up to −20 %. The correct
operating condition for a contactor is based upon a value of the control supply voltage not less
than 85 % of its rated value. The contactor shall not drop at a voltage above 75 % of the rated
control supply voltage.
The sum of voltage excursions at any point on the system (tolerances and transients) from
+20
nominal voltage should not exceed %.
−20
4.6.2.3 Harmonic distortion (voltage waveform)
For voltage harmonic distortion, acceptance limits shall correspond to IEC 61000-2-4:2002,
Class 1. In addition no single harmonic shall exceed 3 %.
Distorting equipment emission levels shall be such that the above limits shall not be exceeded
in normal operating conditions.
For certain installations, where it is confirmed by design study that it is not possible to comply
with the requirements of IEC 61000-2-4:2002, Class 1, higher values, as given in Class 2 may
be accepted, provided the generation and distribution equipment and consumers are designed
to operate at the higher limits.
IEC 61000-2-4:2002 (Table 2) Class 1 states that no single harmonic shall exceed 3 % and the
THD shall not exceed 5 %
IEC 61000-2-4:2002 (Table 2) Class 2 states that no single harmonic shall exceed 6 % and the
THD shall not exceed 8 %
4.6.2.4 Frequency characteristics
Requirements to frequency characteristics are given in Table 4. Tolerances are expressed in a
percentage of the nominal frequency.

– 16 – IEC 61892-1:2015  IEC 2015

Table 4 –Frequency characteristics

Frequency characteristics Value

Frequency tolerance (continuous)
+5
%
−5
Cyclic frequency variation (continuous) 0,5 %

Frequency transient tolerance
+10
%
−10
Frequency transients recovery time maximum 5 s

The sum of frequency excursions at any point on the system (tolerances and transients) from nominal frequency

+12,5
should not exceed %.
−12,5
The frequency tolerance is based on generators operating in “island mode”. In case of
operation in parallel with an external grid a more stringent value has to be applied. This value
has to be agreed between the network owners.
A typical value when operating in parallel with an external network is ±2,5 %.
4.6.3 DC distribution systems
Tolerances for DC system are given in Table 5. Tolerances are expressed in a percentage of
the nominal voltage, measured at the equipment terminal.
Table 5 –Tolerances for DC system
Voltage tolerance (continuous)
+10
%
−15
Cyclic voltage variation 5 %
Voltage ripple (AC r.m.s. over steady DC voltage, 2 %
battery in fully loaded condition)
Voltage ripple VRLA batteries  1 %

Depending of the different configuration of battery charger and batteries system, voltage over
10 % of nominal value could be present in the DC system during full or boost charging. In this
case adequate measures should be taken to keep the voltage on the equipment terminal within
the limits specified above.
Configuration with load directly connected to battery charger and battery system without any

voltage stabilizer device shall be accepted only in absence of load sensible to voltage variation
over 10 %.
The transient recovery time shall not exceed 2 s maximum.
Fast transients e.g. spikes caused by switching, peak impulse voltage amplitude shall not
exceed the values given in Table 6.

Table 6 – Fast transients
System voltage Peak impulse voltage amplitude

24 V DC systems 500 V
110 V DC systems 1 500 V
220 V DC systems 2 500 V
600 V DC system 4 000 V
1 000 V DC system 6 000 V
NOTE The figures are in accordance with IEC 60664-1. Values for DC systems with rated voltage above 1 000 V

are not given in that standard

4.7 Manual disconnection
It shall be possible to de-energize electrical apparatus from an appropriate location, e.g. the
units central control room, if its continued energization would lead to hazards (e.g. spreading of
fire). Electrical apparatus which shall continue to operate to prevent additional danger shall not
be included in the emergency switch-off circuit.
For special requirements to shutdown of equipment in hazardous areas due to emergency
situations such as gas leakage, reference is made to IEC 61892-7.
4.8 Electrical apparatus for explosive gas atmospheres
Electrical apparatus and cables shall, to the extent possible, be located in a non-hazardous
area. Where it is not possible to do this it shall be located in the least hazardous area.
When an apparatus is required to be suitable for use in explosive gas atmospheres, it shall
comply with the requirements of IEC 61892-7. Such equipment shall be constructed and tested
in accordance with the requirements of the IEC 60079 series as required in IEC 61892-7 and
be certified as fit for purpose for the actual ambient temperature and other environmental
conditions, to the satisfaction of the appropriate authority.
NOTE In most countries, it is required that certification is done by an independent testing authority.
4.9 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.

NOTE Information regarding clearance and creepage distances are given in the specific equipment standards,
referred to in IEC 61892-3.
4.10 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.
As a consequence of this clause, insulating materials in important applications, such as busbar
supports, etc., should have
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