The surface temperature of the cable is basically safe below 60 degrees. From the perspective of power supply maintenance, of course, the lower the temperature, the better.
The reasons for the cable heating during operation are as follows:

1. The resistance of the cable conductor does not meet the requirements, causing the rubber cables to generate heat during operation.
2. Inappropriate cable selection, the conductor cross-section of the cable used is too small, and overload occurs during operation. After a long time of use, the heating and heat dissipation of the cable will become unbalanced and cause heating.
3. When the cables are installed too densely, the ventilation and heat dissipation effect is not good, or the cables are too close to other heat sources, which affects the normal heat dissipation of the cables, and may also cause the cables to generate heat during operation.
4. The joint production skills are not good, the crimping is not tight, and the touch resistance at the joint is too large, which will also cause the cable to generate heat.
5. The insulation performance between phases of the cable is not good, the insulation resistance is small, and heating will also occur during operation.
6. The partial sheath of the armored cable is damaged, which will slowly damage the insulation performance after water enters, resulting in a gradual decrease in insulation resistance, and heating during cable operation.
After the cable heats up, if the cause is not found and the fault is rectified in time, the insulation thermal breakdown will occur after the cable continues to be energized. It may cause a short circuit trip of the cable, which may cause a fire.
Therefore, we should avoid it in time and try to reduce unnecessary losses.