1.1 Exposed metal parts of electrical machines
or equipment which are not intended to be live but which are liable
under fault conditions to become live shall be earthed unless the
machines or equipment are:
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.1 supplied at a voltage not exceeding 50 V direct
current or 50 V root mean square between conductors; auto-transformers
shall not be used for the purpose of achieving this voltage; or
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.2 supplied at a voltage not exceeding 250 V by
safety isolating transformers supplying only one consuming device;
or
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.3 constructed in accordance with the principle
of double insulation.
1.2 The Administration may require additional
precautions for portable electrical equipment for use in confined
or exceptionally damp spaces where particular risks due to conductivity
may exist.
1.3 All electrical apparatus shall be so constructed
and so installed as not to cause injury when handled or touched in
the normal manner.
2 Main and emergency switchboards shall be so
arranged as to give easy access as may be needed to apparatus and
equipment, without danger to personnel. The sides and the rear and,
where necessary, the front of switchboards shall be suitably guarded.
Exposed live parts having voltages to earth exceeding a voltage to
be specified by the Administration shall not be installed on the front
of such switchboards. Where necessary, nonconducting mats or gratings
shall be provided at the front and rear of the switchboard.
3.1 The hull return system of distribution shall
not be used for any purpose in a tanker, or for power, heating, or
lighting in any other ship of 1,600 gross tonnage and upwards.
3.2 The requirement of paragraph 3.1 does not
preclude under conditions approved by the Administration the use of:
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.1 impressed current cathodic protective systems;
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.2 limited and locally earthed systems; or
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.3 insulation level monitoring devices provided
the circulation current does not exceed 30 mA under the most unfavourable
conditions.
3.2-1 For ships constructed on or after 1 October
1994, the requirement of paragraph 3.1 does not preclude the use of
limited and locally earthed systems, provided that any possible resulting
current does not flow directly through any dangerous spaces.
3.3 Where the hull return system is used, all
final subcircuits, i.e. all circuits fitted after the last protective
device, shall be two-wire and special precautions shall be taken to
the satisfaction of the Administration.
4.1 Earthed distribution systems shall not be
used in a tanker. The Administration may exceptionally permit in a
tanker the earthing of the neutral for alternating current power networks
of 3,000 V (line to line) and over, provided that any possible resulting
current does not flow directly through any of the dangerous spaces.
4.2 When a distribution system, whether primary
or secondary, for power, heating or lighting, with no connection to
earth is used, a device capable of continuously monitoring the insulation
level to earth and of giving an audible or visual indication of abnormally
low insulation values shall be provided.
4.3 Ships constructed on or after 1 October 1994,
in lieu of the provisions of paragraph 4.1, shall comply with the
following requirements:
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.1 Except as permitted by paragraph 4.3.2 earthed
distribution systems shall not be used in a tanker.
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.2 The requirement of paragraph 4.3.1 does not
preclude the use of earthed intrinsically safe circuits and in addition,
under conditions approved by the Administration, the use of the following
earthed systems:
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.2.1 power-supplied control circuits and instrumentation
circuits where technical or safety reasons preclude the use of a system
with no connection to earth, provided the current in the hull is limited
to not more than 5 A in both normal and fault conditions; or
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.2.2 limited and locally earthed systems, provided
that any possible resulting current does not flow directly through
any of the dangerous spaces; or
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.2.3 alternating current power networks of 1,000
V root mean square (line to line) and over, provided that any possible
resulting current does not flow directly through any of the dangerous
spaces.
5.1 Except as permitted by the Administration
in exceptional circumstances, all metal sheaths and armour of cables
shall be electrically continuous and shall be earthed.
5.2 All electric cables and wiring external to
equipment shall be at least of a flame-retardant type and shall be
so installed as not to impair their original flame-retarding properties.
Where necessary for particular applications the Administration may
permit the use of special types of cables such as radio frequency
cables, which do not comply with the foregoing.
5.3 Cables and wiring serving essential or emergency
power, lighting, internal communications or signals shall so far as
practicable be routed clear of galleys, laundries, machinery spaces
of category A and their casings and other high fire risk areas. In
ro-ro passenger ships, cabling for emergency alarms and public address
systems installed on or after 1 July 1998 shall be approved by the
Administration having regard to the recommendations developed by the
Organizationfootnote. Cables connecting fire
pumps to the emergency switchboard shall be of a fire-resistant type
where they pass through high fire risk areas. Where practicable all
such cables should be run in such a manner as to preclude their being
rendered unserviceable by heating of the bulkheads that may be caused
by a fire in an adjacent space.
5.4 Where cables which are installed in hazardous
areas introduce the risk of fire or explosion in the event of an electrical
fault in such areas, special precautions against such risks shall
be taken to the satisfaction of the Administration.
5.5 Cables and wiring shall be installed and supported
in such a manner as to avoid chafing or other damage.
5.6 Terminations and joints in all conductors
shall be so made as to retain the original electrical, mechanical,
flame-retarding and, where necessary, fire-resisting properties of
the cable.
6.1 Each separate circuit shall be protected against
short circuit and against overload, except as permitted in regulations 29 and 30 or where the Administration may
exceptionally otherwise permit.
6.2 The rating or appropriate setting of the overload
protective device for each circuit shall be permanently indicated
at the location of the protective device.
7 Lighting fittings shall be so arranged as to
prevent temperature rises which could damage the cables and wiring,
and to prevent surrounding material from becoming excessively hot.
8 All lighting and power circuits terminating
in a bunker or cargo space shall be provided with a multiple-pole
switch outside the space for disconnecting such circuits.
9.1 Accumulator batteries shall be suitably housed,
and compartments used primarily for their accommodation shall be properly
constructed and efficiently ventilated.
9.2 Electrical or other equipment which may constitute
a source of ignition of flammable vapours shall not be permitted in
these compartments except as permitted in paragraph 10.
9.3 Accumulator batteries shall not be located
in sleeping quarters except where hermetically sealed to the satisfaction
of the Administration.
10 No electrical equipment shall be installed
in any space where flammable mixtures are liable to collect, e.g.
in compartments assigned principally to accumulator batteries, in
paint lockers, acetylene stores or similar spaces, unless the Administration
is satisfied that such equipment is:
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.1 essential for operational purposes;
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.2 of a type which will not ignite the mixture
concerned;
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.3 appropriate to the space concerned; and
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.4 appropriately certified for safe usage in the
dusts, vapours or gases likely to be encountered.
11 In tankers, electrical equipment, cables and
wiring shall not be installed in hazardous locations unless it conforms
with standards not inferior to those acceptable to the Organization.footnote However, for locations not covered by such
standards, electrical equipment, cables and wiring which do not conform
to the standards may be installed in hazardous locations based on
a risk assessment to the satisfaction of the Administration, to ensure
that an equivalent level of safety is assured.
12 In a passenger ship, distribution systems shall
be so arranged that fire in any main vertical zone as is defined in regulation II-2/3.9
footnote will not interfere with services essential for
safety in any other such zone. This requirement will be met if main
and emergency feeders passing through any such zone are separated
both vertically and horizontally as widely as is practicable.