Nowadays, PVC film is applied to the electric cables. PVC material is plasticized, to be the normal insulator on the cables. The traditional flexible PVC film coated on wire and cable is with lead stabilizer, now it is replaced by the application of Ca based system.
In a fire, the cable with PVC film coated, forms hydrogen chloride gases, the chloride gases clear free radical, it is the reason why PVC material be flame retardants.