What happens to the cable when it encounters fire? Cable fire protection
November 02, 2022
Introduction: In recent years, frequent fire accidents have brought great challenges to the cable industry. When the cable encounters a fire, what steps should be taken? Or what should we do to prevent a cable fire accident before we encounter a fire?
In order to prevent cable fire accidents, the following precautions should be taken:
(1) Select cables that meet the thermal stability requirements. The selected cable, under normal conditions, can meet the heat requirements of the long-term rated load. In the case of a short circuit, it can meet short-term thermal stability and prevent the cable from overheating and catching fire.
(2) Prevent running overload. When the cable is loaded and operated, the rated load operation is generally not exceeded. If the cable is overloaded, the overload running time of the cable must be strictly controlled so as to avoid overheating the cable and causing the cable to catch fire.
(3) Observe the relevant regulations for cable laying. When laying cables, keep them away from heat sources and avoid parallel or cross-arrangement with steam pipes. If they are parallel or intersecting, they should maintain the specified distance and adopt heat insulation measures. All cables shall not be laid on the top or bottom of the heat pipes in parallel; in some pipes In the tunnel or ditch, laying of cables is generally avoided. If laying is required, thermal insulation measures shall be taken. Overlayed cables, especially plastics and rubber cables, shall have thermal insulation measures to prevent thermal influences such as heat pipes; when laying cables, The distance between cables, cables and heat pipes and other pipes, and between cables and roads, railways, buildings, etc., shall be in accordance with the provisions of the regulations; in addition, the cable should be left with a wave shape to prevent winter. The cable stops running and causes excessive tension to damage the cable insulation. Cable bends should ensure a minimum radius of curvature in order to prevent excessive bending and damage to the cable insulation; avoid joints in the cable tunnel, because the cable joints are the weakest insulation in the cable, and the cable joints are prone to short-circuit faults when they must be in the tunnel. When installing an intermediate joint, use a fire-resistant partition to separate it from other cables. The above cable laying regulations are effective in preventing the cable from overheating and insulation damage from catching fire.
(4) Regular inspections. The power cable should be regularly inspected, and the air temperature and cable temperature in the cable ditch should be regularly measured. In particular, the temperature of the large-capacity power cable and cable connector box should be recorded. Find and handle defects through inspections.
(5) Close tightly the cable holes, holes and fire doors and partition walls. In order to prevent cable fires, all cable holes that pass through walls, floors, shafts, and cable trenches into control rooms, cable mezzanines, control cabinets, instrument cabinets, switch cabinets, etc. must be tightly closed (closed, flat, beautiful, and cabled). Do not suffer damage). For longer cable tunnels and their bifurcated crossings, fire walls and fire doors should be provided. Under normal circumstances, the cable trench or the door on the hole should be closed so that once the cable catches fire, it can isolate or limit the combustion range and prevent the spread of fire.
(6) Strip the external jute sheath outside the buried cable. The buried cable has a layer of jute protective layer, such as dipping asphalt, which protects the cables in the direct burial area. When the buried cable enters the cable trench, tunnel, and shaft, the protective layer of jute, such as asphalt, is exposed. Stripped to reduce the risk of fire expansion. At the same time, the cover plate above the cable trench should be covered, and the cover plate is complete, strong, and the welding slag cannot easily fall in, reducing the possibility of cable fire.
(7) Keep the cable tunnel clean and properly ventilated. The cable tunnel or channel shall be kept clean, no garbage and debris shall be piled up, and the accumulated water and accumulated oil in the tunnel and trench shall be promptly removed. In normal operation, the cable tunnel and the channel shall be properly ventilated.
(8) Maintain good lighting of cable tunnels or channels. The lighting in cable layers, cable tunnels, or channels is often kept in good condition, and special ladders are provided for tunnels and trenches that need to be placed on and off to facilitate inspection of operation and suppression of cable fires.
(9) Prevent fire from entering the cable trench. When carrying out open fire near the cable, measures should be taken to prevent the fire from entering the ditch.
(10) Perform regular inspections and tests. According to the regulations and actual conditions of cable operation, the cable should be regularly inspected and tested in order to deal with defects and discover latent faults in a timely manner to ensure the safe operation of cables and avoid the occurrence of cable fires. When entering the cable tunnel or channel for maintenance and testing work, the relevant provisions of the "Working Safety Regulations" shall be followed.
