246 HANDBOOK OF ELECTRICAL ENGINEERING
In addition to injury to health these acid gases can also cause very corrosive damage to
equipment, especially if water is employed during the fighting of the fire. Electronic equipment and
fine stands of wire are particularly susceptible to damage.
Smoke is usually evolved in the combustion of elastomers, e.g., PVC, PCP and CSP especially
if carbon black is present in the compound.
A type of cable known as the ‘low smoke zero halogen’ (LSOH) type has been developed over
the past 20 years for use in enclosed environments where good visibility and damage minimisation
are of high importance e.g., electronic equipment rooms, corridors, emergency exit routes, medical
treatment rooms, living quarters, caissons and basements. The IEC60754 specifies a maximum limit
of 0.5% halogen acid shall be emitted in a fire for a cable to be classed as being of the LSOH type.
Non-metallic materials that provide fairly good ‘low-smoke’ characteristics are EVA, silicon
rubber, XLPE and EPR.
9.5.4 Application of fire retardant and fire resistant cables
The application of fire retardant and fire resistant cables to particular services can be shown in tabular
form, see Table 9.37 below.
Table 9.37. Application of fire retardant and fire resistance cables in a
typical oil industry plant
Services and systems Fire retardance Fire resistance
Deluge systems
√
Drilling system cables
√
Emergency and escape lighting
√
Emergency power and associated
control systems
√
Emergency shutdown systems
√
Emergency telephone systems
√
Emergency UPS cabling systems
√
Escape lighting and signs√
Fire and gas systems√
Fire extinguishing systems√
Fire pump cables√
Helideck lighting√
HVAC fire dampers and
control systems√
Instrumentation cables√
Internal wiring in switchboard,
Panels etc.√
Intrinsically safe systems√
Navigational aides
√
Normal service systems
√
Normal UPS systems
√
Public address systems
√
Telecommunications
√