What To Do in The Event Of An Electrical Fire

After a fire breaks out, electrical equipment and electrical lines may be live, and if care is not taken, it may cause an electric shock accident. According to the site conditions, if the power can be cut off, the fire should be cut off; if the power cannot be cut off, the fire should be extinguished with electricity. Electrical equipment such as power transformers and oil-rich circuit breakers are filled with a large amount of oil. After a fire, oil injection or even an explosion may occur, causing the flame to spread and expand the scope of the fire. This must be paid attention to.

1. SHOCK HAZARD AND LOSS OF ELECTRICAL

In the event of a fire in electrical equipment or electrical circuits, if the power supply is not cut off in time, the body of the firefighter or the equipment held by the firefighter may touch the live part and cause an electric shock accident. The use of conductive fire agents, such as direct current water jets from water guns and foam from foam fire extinguishers, to live parts may also cause electric shock accidents. After a fire occurs, the electrical equipment may be short-circuited due to insulation damage; the electrical circuit may be short-circuited to the ground due to broken wires, which may cause the normally uncharged metal frame and ground to be charged, and may also cause contact voltage or step voltage electric shock hazard.
Therefore, when a fire is found, the first thing to do is to cut off the power supply. Pay attention to the following points when cutting off the power supply:
(1) After a fire occurs, due to damp and smoke, the insulation capacity of the switchgear will be reduced. Therefore, it is best to use an insulating tool to operate the switchgear.
(2) For high voltage, the circuit breaker should be operated first instead of the isolating switch to cut off the power supply; for low voltage, the electromagnetic starter should be operated first instead of the knife switch to cut off the power supply, so as not to cause arc short circuit.
(3) The place where the power is cut off should be selected appropriately to prevent the fire extinguishing work from being affected after the power is cut off.
(4) When cutting the wires, the wires of different phases should be cut at different positions to avoid short circuit. When cutting the wires in the air, the

cutting position should be selected near the support in the direction of the power supply, so as to prevent the wires from cutting and falling down, causing grounding short circuit and electric shock accidents.

2. Safety requirements for live fire extinguishing

Sometimes, in order to gain time to extinguish the fire and prevent the fire from expanding, it is too late to cut off the power; or due to the needs of fire extinguishing and production, the power cannot be cut off, so it is necessary to put out the fire with electricity. Pay attention to the following points when extinguishing a live fire:
(1) Appropriate fire extinguishers should be selected according to the characteristics of the site. The fire extinguishing agents of carbon dioxide fire extinguishers and dry powder fire extinguishers are non-conductive and can be used for live fire extinguishing. The fire extinguishing agent (aqueous solution) of the foam fire extinguisher has certain conductivity and affects the insulation of electrical equipment, so it is not suitable for live fire extinguishing.
(2) When using a water gun to extinguish a fire, it is advisable to use a spray water gun. The leakage current of this water gun flowing through the water column is small, and it is safer to put out a live fire. When using an ordinary DC water gun to extinguish a fire, in order to prevent the leakage current through the water column from passing through the human body, the nozzle of the water gun can be grounded (that is, the water gun can be connected to the buried grounding body, or connected to the ground network ground plate, or connected to the thick copper wire network shoe cover); it is also possible for the firefighters to wear insulating gloves, insulating boots or wear pressure equalizing suits.
(3) Keep a necessary safe distance between the human body and the charged body. When extinguishing fire with water, the distance from the nozzle of the water gun to the charged body: the voltage is 1OkV and below should not be less than 3m, and the voltage is 220kV and above should not be less than 5m. When using a fire extinguisher with non-conductive fire extinguishing agent such as carbon dioxide to extinguish fire, the minimum distance from the body, nozzle to the charged body should not be less than 0.4m if the voltage is 10kV, and should not be less than 0.6m if the voltage is 35kV.
(4) When extinguishing fires on aerial equipment such as overhead lines, the elevation angle between the human body position and the electrified body should not exceed 45°.

3. Fire extinguishing of oil-filled electrical equipment

The oil of oil-filled electrical equipment usually has a flash point between 130 and 140 ℃, which is relatively dangerous. If the fire occurs only outside the equipment, carbon dioxide and dry powder fire extinguishers can be used to extinguish the fire. If the fire is large, cut off the power and put out the fire with water. If the fuel tank is damaged, the fuel injection burns, and the fire is very strong, in addition to cutting off the power supply, if there is an accidental oil storage pit, try to put the oil into the oil storage pit. The oil fire in the pit and on the ground can be extinguished with foam. To prevent the burning oil from flowing into the cable trench and spreading along the trench, the oil fire in the cable trench can only be extinguished by covering it with foam.
When a rotating electrical machine such as a generator or a motor catches fire, in order to prevent the shaft and bearing from deforming, it can be rotated slowly, sprayed with water to extinguish the fire, and allowed to cool evenly; carbon dioxide or steam can also be used to extinguish the fire, but it is not suitable to use dry powder, sand or soil to extinguish the fire, so as not to damage the insulation of electrical equipment.