Power cable through a certain load current, it will certainly heat up, with the increase of load current, the higher the surface temperature of the cable, if not dealt with in time, the consequences can be imagined. For example: polyvinyl chloride (PVC) cables, is the core temperature of 70 degrees for the upper limit of consideration, the surface temperature will be lower 5 to 10 degrees. So the cable surface temperature below 60 degrees is basically safe, from power maintenance considerations, of course, the lower the temperature the better.

　　Cable heating in operation for the following reasons:

　　1, the cable conductor resistance does not meet the requirements, resulting in cable heating in operation.

　　2, the cable selection type is not appropriate, resulting in the use of the cable conductor cross-section is too small, the operation of the overload phenomenon, after a long period of time, the cable's heat and heat imbalance caused by the phenomenon of heat generation.

　　3, cable installation is arranged too dense, ventilation and heat dissipation effect is not good, or the cable is too close to other heat sources, affecting the normal heat dissipation of the cable, may also cause the cable in operation to produce heat phenomenon.

　　4, the joints manufacturing technology is not good, crimping is not tight, resulting in excessive contact resistance at the joints, which can also cause the cable heating phenomenon.

　　5, the cable phase insulation performance is not good, resulting in insulation resistance is small, the operation will also produce heat phenomenon.

　　6, armored cable local sheath damage, water on the insulation performance of slow damage caused by the role of insulation resistance gradually reduced, will also cause the cable run in the heating phenomenon.

　　Cable heating phenomenon, such as not find the cause of timely troubleshooting, the cable continues to run continuously energized will produce thermal breakdown of the insulation phenomenon. Caused by the cable phase to phase short circuit tripping phenomenon, may cause a serious fire.