A power cable is a long, cylindrically symmetric structure with a dielectric which operates at relatively high electrical stress. This solid dielectric is covered with a semi-conductive shield, thus forming a cable core on which a metallic ground shield is applied. Power cables typically include one or more electrical conductors, several layers of polymeric materials including a first or inner semi conducting shield layer (conductor or strand shield), an insulation layer, a second or outer semi conducting shield layer (insulation shield), a metallic tape or wire shield, and a protective jacket. Polyethylene and cross-linked polyethylene have been extensively used as an insulation for a DC power cable since they are superior in dielectric strength and other dielectric characteristics. Cross-linked polyethylene insulated electric power cables have various advantages of not only excellent electrical property, mechanical property, and heat-resistance property, but also easy maintenance. Because of these advantages, the cross-linked polyethylene insulated electric power cable is the mainstream type of power-transmission cable. Internal electrical wiring in residential homes for 15 ampere AC power supply has been standardized as 14-2G type NM-B sheathed cable. This sheathed cable consists of three 14 gage solid conductors, with the line and neutral conductors individually insulated and disposed in a parallel flat lay on opposite sides of an insulated ground conductor.