Power cable through a certain load current, will heat, with the increase of load current, the higher the cable surface temperature, if not handled in time, the consequences can be imagined. For example: polyvinyl chloride (PVC) cable, the core temperature is considered as the upper limit of 70 degrees, and the surface temperature will be 5 to 10 degrees lower. Therefore, the cable surface temperature below 60 degrees is basically safe, from the power supply maintenance consideration, of course,