What Are the Causes of Wire and Cable Explosion and Fire?

The insulation layer of power cables is composed of flammable materials such as paper, oil, hemp, rubber, plastic, and asphalt. Therefore, there is a possibility of fire and explosion in cables. What are the causes of fire and explosion in wire and cable?

Insulation Damage Leading to Short Circuit Fault: The protective lead strip of the power cable is damaged during the laying process or mechanically damaged during operation, causing insulation breakdown between the cable and the lead strip, and the resulting arc ignites the insulation material and outer protective layer material of the cable.

Cable Long-Term Overload Operation: Prolonged overload operation causes the operating temperature of the cable's insulation material to exceed the highest allowable temperature for normal heating, leading to insulation aging and drying. This insulation aging and drying phenomenon usually occurs throughout the entire cable line. Due to the aging and drying of the cable insulation, the insulation and mechanical properties of the insulation material degrade or are lost, making the cable prone to burn out when worn, and even to multiple burnouts along the entire length of the cable.

Oil-filled cables may leak due to significant height differences. When the height difference is considerable, oil leakage can occur. As the oil flows, the upper part of the cable dries out due to the loss of oil. This section of the cable experiences increased thermal resistance, leading to premature charring and breakdown of the paper insulation. Furthermore, as the oil flows downward, the space at the upper cable head is released, creating a vacuum that makes the cable susceptible to moisture absorption, causing the ends to become damp. Due to the accumulated oil at the lower part of the cable, the static pressure is high, resulting in oil leakage from the cable head. Moisture absorption and oil leakage increase the likelihood of faults and fires.

Intermediate junction box insulation breakdown: Due to improper crimping, welding, or material selection, the intermediate and secondary junctions of the cable junction box are oxidized, heated, and coated during operation. During the manufacturing of the cable intermediate joints, the quality of the insulating material filled in the intermediate and secondary junction boxes does not meet the requirements. Air bubbles are present in the box during the pouring of the insulating material, and the cable box seal is damaged, allowing moisture to leak in. These factors can lead to insulation breakdown and short circuits, causing cable explosions and fires.

Cable Head Damage: Due to moisture contamination on the cable head surface, the porcelain sheath was damaged, and the spacing between the incoming and outgoing lines was too small, causing arcing and ignition. This resulted in the insulation on the cable head surface and the outgoing insulation being burned.

External Cable Fires Caused by External Fires and Heat Sources: Cable fires can be triggered by various factors, including the spread of oil system fires, explosions of oil circuit breakers, spontaneous combustion of coal powder in boiler or coal conveying systems, scorching from high-temperature steam pipes, chemical corrosion from acids and alkalis, welding sparks, and more.