To avoid mechanical injury to cable

To prevent entry of moisture

To protect the metallic sheath

To provide flexibility to cable

To provide flexibility

To reduce conductivity

To provide mechanical strength

To reduce the weight

Hygroscopic

High insulation resistance

Low mechanical strength

High conductivity

Impregnated paper

Varnished cambric

Polyvinyl Chloride

Rubber

Absorbs moisture

Hard

Low mechanical strength

High hygroscopic