When the wires and cables are powered on, the metal core will heat up. With the increase of power on time, the temperature of the wire and cable surface will become higher and higher. If it is not handled in time, the consequences can be imagined. The sheath of our commonly used PVC wires and cables is PVC. The upper limit of the core temperature is 70 degrees, and the surface temperature will be 5-10 degrees lower. Therefore, it is safe to keep the cable surface temperature below 60 ℃. From the perspective of power maintenance, of course, the lower the temperature, the better.

It is normal for wires and cables to overheat, but there are some conditions that may cause wires and cables to overheat. Today, Zhujiang Cable Editor will talk about the causes of overheating of wires and cables in use.

1、 Causes of overheating of wires and cables in use

1. The crimping of wires and cables is not tight when jointing, which leads to excessive resistance at the joints, and the wires and cables may overheat when being energized for a long time;

2. The design, planning and installation of wires and cables are not well considered. Wires and cables that do not conform to the cable conductor resistance are selected. When the current is greater than the large negative current, overheating will occur;

3. Improper selection of cable leads to the conductor section of the used cable is too small, and overload occurs during transportation. After a long time of use, the heating and heat dissipation of the cable are unbalanced, resulting in overheating;

4. Due to the unprofessional installation personnel, the cables are arranged too densely, the ventilation and heat dissipation effect is poor, or the cables are too close to other heat sources, which affects the normal heat dissipation of the cables, and may also cause overheating of the cables during operation;

5. The interphase insulation performance of cables is poor, resulting in low insulation resistance and overheating during transportation;

6. The partial sheath of armored cable is damaged, and the insulation performance is slowly damaged after water ingress, resulting in gradual reduction of insulation resistance and overheating during cable operation;

7. Many low-quality wires and cables on the market have poor insulation, resulting in smaller insulation resistance, and overheating will occur if they operate for a long time;

8. Improper selection of wire and cable models, such as fire-resistant wire and cable should be selected under high temperature or flammable environment.