There are many insulations used in producing the various cables used to deliver electric power. Extruded insulations used for wire and cable are classified as either a thermoplatic or a thermoset material. Thermoplastic materials tend to lose their form upon subsequent heating, while thermosetting materials tend to maintain their form. These insulations range from thermoplastic polyvinyl chloride to the most recent advances in tree-retardent crosslinked polyethylene and synthetic rubber compounds. PE is popular bacause of its relatively low price, processability, resistance to chemicals and moisture, electrical properties, and low temperature flexibility.
PE is produced in low, linear low, medium, and high densities.
As the density increases, so does the hardness, yield strength, stiffness, heat and chemical resistance. UV radiation can degrade both the physical and electrical properties. PE's electrical properties are excellent. A disadvantage of PE is that, like most plastics, it is susceptible to degradation by corona discharges. PE also may experience degradation from treeing when it is subjected to high electrical stress.