The root cause of any electrical fire is the insulation of the circuit or wire. If the insulation is weak or damaged, it may lead to spark, electrical shock or fire in the system causing major accidents and causality. The best way to avoid electrical fire is to maintain the insulation of electrical wires and equipment.

The insulation of the electric cable is generally made up of rubber or plastic. The amount of smoke generated by the plastic in case of fire is dependent on factors such as nature of plastic, type of additive used, flame of fire and ventilation arrangements. In general, most plastics produce a very dense smoke when heated.

Some plastic burns very clearly when subjected to heat and flame, producing very less smoke. If insulation used is of urethane foam, a very dense smoke is produced and visibility in the room is lost. Some plastics contain Poly Vinyl Chloride (PVC), which produces pungent, and irritating odor.

Rubber when used for insulation produces a dense, black, oily smoke and has some toxic qualities. The most common gases produced during combustion of rubber are hydrogen sulphide and sulphur di-oxide. Both these gases are dangerous for health and can be fatal in certain cases.

Ways to Reduce these Hazards

The following steps should to taken as preventive measures:

·         Cables having E.P.R (Ethylene Propylene Rubber) insulation with necessary sheathing of Poly Chloro Prene or Chloro Sulphonated Polyethylene ( PCP or CSP) may be used to protect the insulation against fire

·         G.I armor may be used to protect insulation from fire but needs to be earthed

·         By using cables having high oxygen index number, the number allotted to material depending on minimum percentage of oxygen required to sustain combustion

·         If the material used is having oxygen index number 27, it means that minimum percentage of oxygen required to burn the material is 27 % which is well above the normal atmospheric oxygen percentage of 21 %. Thus, the insulation material will not catch fire

Important Precautions for Installation of Electric Cables

1) The cables and wirings external to the equipment must have flame retardant properties and should be installed in such a manner that it should not interfere with the original flame retarding properties.

2) Cables and wirings for emergency equipment, lightings, communication and signal should be kept away from spaces such as galley, laundries, machinery space of category A & other high risk areas

3) Special precautions are to be taken for cable installation in hazardous area as it might lead to explosion in case of electrical fault.

4) Terminations and joints are to be made in such a manner that they should retain their original fire resisting properties.

5) Avoid cable for damage and chaffing during installation.

6) Fireproof glands to be used in case of cables passing through the bulkhead to prevent fire from one compartment to other.