Wires and cables will be affected by different factors in different use environments, among which moisture is the biggest influencing factor, so the insulation and sealing of wires and cables must be done well.
In urban power grid reconstruction projects, wires and cables, especially polyethylene insulated power cables, have been widely used. However, due to the particularity of cables, special requirements are placed on the installation, operation and maintenance of cables. Moisture or water ingress in cables reduces the resistance of cable insulation materials, which is one of the important aspects that cause operation accidents in wire and cable lines.
Causes and hazards of moisture in wires and cables
When new wires and cables are shipped out of the factory, both ends are sealed with plastic sealing sleeves. However, after a section is used at the construction site according to the actual situation, the remaining part is simply wrapped with plastic cloth. Since they are usually placed in the open air and the sealing is not good, it is inevitable that water vapor will penetrate into the cables over time.
When laying wires and cables, they often need to cross roads, bridges, and culverts. Due to weather or other reasons, a lot of water often accumulates in the cable trench. During the laying process, it is inevitable that the cable head will be immersed in water. Water will enter the cable due to the loose or damaged plastic wrapping. In addition, during traction and pipe threading, the outer sheath or even the steel armor may be scratched. This phenomenon is particularly prominent when mechanical traction is used.
After the laying of wires and cables is completed, the cable head cannot be made in time due to the limitations of on-site construction conditions, so that the unsealed cable break is exposed to the air for a long time, or even immersed in water, causing a large amount of water vapor to enter the cable.
During the production process of wire and cable heads (including terminal heads and intermediate joints), due to the negligence of construction workers, the newly processed cable ends may accidentally fall into the accumulated water on site.
In the normal operation of the cable, if a breakdown or other fault occurs for some reason, the accumulated water in the cable trench will enter the cable along the fault point; in civil construction, especially in construction sites using large construction machinery, cable damage or breakdown accidents caused by various human factors are also common. When such accidents occur, the insulation of the wires and cables is severely damaged, which can also cause water to enter the cables.
Post time: 2025-05-09
