Electric cables are typically covered with:

Polyvinyl chloride is commonly used to cover electrical lines.

Electric wires are constructed of materials that carry electricity well, such as copper. Because electrical cables are comprised of copper, they cannot be exposed inside the system.

A PVC coating is necessary not only to improve the productivity of the wires but also to protect the person from receiving an unexpected shock and to indicate to the customer which wire is for which when the wires are colored for different purposes.

This is due to the fact that PVC is an insulator.