Question

what is the reason behind covering wires carring electriccity with rubber in some places

Answer 1

Electrical wires are insulated with rubber covering so that anybody touching it does not receive any electrical shock

Answer 2

Most electrical wire is covered in a rubber or plastic coating called insulation.The purpose of insulation covering the metal part of an electrical wire is to prevent accidental contact with other conductors of electricity, which might result in an unintentional electric current through those other conductors.