If it is performing as a jacket, it keeps out water and other contaminants. The convering could be acting as an armor because it provides mechanical protection to the insulated conductors. PVC, Nylon and PE are applied using thermoplastic extrusion lines which heat the material to the melting point and form it over the core. The material is then cooled, usually in a water trough, and wound onto a reel. CSP differs because it is a thermoset material.
Some heat is used to soften the material so that it can be formed around the core.
It is then necessary to crosslink the material to obtain its full properties. These materials conform to one or more of the standards issued by AEIC, ASTM, CSA, ICEA, IEEE, NEMA, and UL as directed by specific requirements and applications. Lead Sheathing Lead is one of the oldes sheathing materials used on power cables, dating back to the early 1900s. In the sheathing operation, molten lead is fed into cylinder. After a partial cooling, a hydraulic piston forces the lead through an annular die forming it tightly around the cable.