Cable Materials

Material choice sets the temperature rating, the flexibility, the chemical resistance and the fire behaviour of a cable, and it usually sets the price more than the conductor cross-section does. Cross-linked polyethylene allows a higher continuous conductor temperature than PVC and lower dielectric loss, which is why it displaced PVC on power cables above the lowest voltages; ethylene propylene rubber tolerates more repeated flexing and is preferred where a cable must move.

Halogen-free and low-smoke compounds exist because burning PVC releases hydrogen chloride, which is corrosive to equipment and hazardous in a confined space. Halogen-free formulations trade some mechanical toughness and cost for low smoke emission and the absence of acid gas, which is why the requirement usually comes from the installation — tunnels, metro, data halls, offshore — rather than from the cable.