The power cable is made of three main components, namely, conductor, dielectric, and sheath. The conducting path for the current in the cable is provided by the conductor. The insulation or dielectric withstands the service voltage and isolates the live conductor with other objects. The sheath does not allow the moistures to enter and protects the cables from all external influences like chemical or electrochemical attack and fire. http://www.jinmaifastener.com/cable-components/