Every conductor must be insulated to keep them apart , keep the flow of current within the conductor and prevent its leaving or leakng from the conductor at random along its length . The following types of insulation are in use .
Thermoplastic PVC
polyvinyl chloride is one of the commonest materials used by man today . It is a man-made thermo-plastic which is tough , incombustible and chemically unreactive . Its cheif drawback is that it softens at temperatures above about 70 celcius . it does not deteriorate with age and wiring carried out in PVC insulated cable should not need to be renewed in the way that wiring insulated with most of the older materials had to be . PVC insulated cable consists of cables of the types described above with a continuous layer or sleeve of PVC around them . The olny restriciton on this type of cable is that is should not be used in ambient temperatures higher than 70 celcius.
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