What Are the Causes of Wire and Cable Fires?

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 electrical wires and cables?

Short Circuit Fault Caused by Insulation Damage: The protective grounding strips of power cables are damaged during installation or due to mechanical damage during operation, leading to insulation breakdown between the cable and grounding strips, causing arcs that ignite 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 permissible temperature for normal heating, leading to insulation aging and drying. This insulation aging and drying phenomenon typically occurs throughout the entire cable line. Due to the aging and drying of the insulation material, its insulation and mechanical properties deteriorate or are lost, making the cable prone to burn out easily 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 there is a large height difference in oil-filled cables, oil leakage may occur. Due to the flow, the upper part of the cable dries out due to the loss of oil. This section of the cable experiences increased thermal resistance, causing the paper insulation to burn and puncture prematurely. Additionally, as the oil from the upper part flows downward, the space at the upper cable head is released, creating a vacuum that makes the cable prone to absorbing moisture, resulting in dampness at the ends. Due to the accumulation of oil at the lower part of the cable, the static pressure is high, leading to oil leakage at the cable head. Moisture and oil leakage in the cable increase the likelihood of faults and fires.

Electrical Cable

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. The quality of the insulating material filled in the intermediate and secondary junction boxes during the production of cable intermediate joints does not meet the requirements. Air bubbles are present in the box during the pouring of the insulating material, and the cable box is not sealed properly, allowing moisture to leak in. These factors can lead to insulation breakdown and short circuits, causing cable explosions and fires.

Cable Head Burnout: Due to damp and contaminated surface of the cable head, the porcelain sleeve is damaged, the spacing between the incoming and outgoing lines is too small, resulting in corona ignition, causing burnout of the insulation on the cable head surface and the outgoing insulation.

External cable fires caused by external fires and heat sources: Such as the spread of oil system fires, explosion of oil circuit breakers leading to fire spread, spontaneous combustion of coal powder in boiler pulverizing or coal conveying systems, roasting by high-temperature steam pipes, chemical corrosion by acids and alkalis, welding sparks, etc., can trigger cable fires.