Question

why electric wire coated with PVC ?

Answer 1

Beacause PVC is a bad conductor of electricity.
For prevention from electric shock, PVC coatings is used.

Answer 2

Explanation:

The electrical wires are made up of copper and there are few which less cost are and made up of aluminium and copper mixed now, wires can't be laid naked within the system.

A coating of PVC is required not only it enhances the productivity of the wires, it also provides protection to the user from getting unconditional shock and it also indicate the user which wire is for which purpose when the wires are coloured differently for different purposes.