When an electrical cable is subjected to a certain load current, it will definitely generate heat. As the load current increases, the surface temperature of the cable will rise. If not dealt with in time, the consequences can be imagined. For example, for polyvinyl chloride (PVC) cables, the upper limit for the core temperature is considered to be 70 degrees Celsius, and the surface temperature will be 5 to 10 degrees lower. Therefore, the surface temperature of the cable is basically safe when it is below 60 degrees Celsius. From the perspective of power supply maintenance, of course, the lower the temperature, the better.
The reasons for the heating of power cables during operation are as follows:
1. The resistance of the cable conductor does not meet the requirements, resulting in overheating of the cable during operation.
2. The selection of cables was inappropriate, resulting in the conductor cross-sectional area of the used cables being too small. During operation, an overload phenomenon occurred. After long-term use, the imbalance in heat generation and heat dissipation of the cables led to the occurrence of overheating.
3. During cable installation, the cables are arranged too closely, resulting in poor ventilation and heat dissipation. Or the cables are placed too close to other heat sources, which not only hinders the normal heat dissipation of the cables but also may cause the cables to generate heat during operation.
4. The manufacturing technique of the joints is poor, and the compression is not tight, resulting in excessive contact resistance at the joint and causing the cable to overheat.
5. The insulation performance between the cables is poor, resulting in a relatively low insulation resistance. During operation, this also leads to overheating.
6. The local sheath of the armored cable is damaged. When water seeps in, it causes a gradual deterioration of the insulation performance, resulting in a gradual decrease in insulation resistance and also causing overheating during the operation of the cable.
When an electric cable generates a heating phenomenon, if the cause is not identified and the fault is not promptly eliminated, the cable will continue to operate under continuous power supply and may experience insulation thermal breakdown. This can lead to a phase-to-phase short circuit and tripping of the cable, and in severe cases, it may even cause a fire.
Post time: Jun-22-2026