1. Reduce the operational life of wire and cable.
After the long-term operation of the wires, especially in direct burial, immersion in water, exposure to the open air or corrosive environment, the insulation level and mechanical level of the sheath at the thinnest point will decrease due to the corrosion of the external medium for a long time. At the same time, the routine sheath test detects or a line ground fault occurs, and the thinnest point may be broken down. In this way, the protective effect of the cable jacket is lost.
In addition, the internal consumption cannot be ignored, and the long-term energization of the wire and cable will generate a lot of heat. (The conductor is allowed to work at 70 ℃, and the long-term use temperature of PVC should not exceed 65℃.) Therefore, the wire and cable is actually in the "internal and external troubles"
2. Increase the difficulty of the laying process.
With the development of global industry, more and more environmental requirements require high-voltage cable products to have a small outer diameter. In the process of laying, it is necessary to consider leaving a gap, so as to dissipate the heat generated after the wire and cable are energized. Excessive thickness of the sheath will increase the difficulty of laying, so the thickness of the sheath is strictly in accordance with the relevant standards, otherwise, it will not protect the wire and cable. Nor can we blindly pursue its thickness.