9.1.1 The additional requirements for electrical equipment on oil storage
units for the storage of oil in bulk having a flash point not exceeding 60°C
(closed-cup test) are given in this Section.
9.1.2 Spaces or locations associated with or close to the arrangements for oil
storage, loading and discharging are to be classified into hazardous zones, and
electrical equipment is to be selected and installed, in accordance with IEC 60092-
502: Electrical Installations in Ships – Tankers – Special Features.
9.1.3 Alternatively, classification of these spaces or locations may be
carried out by application of the methods given in IEC Publication 60079-10-1 or EI
(formerly IP) Part 15, taking into account the probable frequency, duration and
rates of leakages of flammable material from all sources (including structural
defects) and the degree and availability of ventilation at the location. The
selection and installation of electrical equipment is to meet the requirements of
Pt 7, Ch 2, 8 Electrical equipment for use in explosive gas atmospheres for the relevant zone.
9.1.4 In addition to the requirements of
Pt 7, Ch 2, 8 Electrical equipment for use in explosive gas atmospheres, cables, other than those of intrinsically
safe circuits, in hazardous zones or spaces, or which may be exposed to stored oil,
oil vapour or gas, are to be either:
- mineral insulated with copper sheath; or
- armoured or braided (for mechanical protection and earth
detection) with non-metallic impervious sheath.
9.1.5 Where electrical equipment is not suitable for a hazardous area into
which the space has an opening, the electrical supply to the equipment is to be
disconnected, provided shutting down the equipment will not introduce a hazard. In
this case, an alarm may be given, in lieu of shutdown, upon loss of overpressure or
ventilation, and a means of disconnection of the electrical equipment, capable of
being controlled from a manned station, provided in conjunction with an agreed
operational procedure. Where the means of disconnection (whether controlled
automatically or manually) is located within the space, it is to be equipment of a
type suitable for use in a Zone 1 location.
9.1.6 Within any space classified as safe by virtue of pressurisation, any
electrical equipment required to operate upon loss of overpressure and lighting
fittings and equipment within the air-lock is to be of a type suitable for a Zone 1
location. Means are to be provided to prevent electrical equipment, other than that
suitable for a Zone 1 location, being energised until the atmosphere within the
space is made safe, by air renewal of at least 10 times the internal volume of the
space.