【Fire Safety Tips】Basic Knowledge on Extinguishing Electrical Fires

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From a fire-fighting perspective, electrical fires have two characteristics that need attention: first, the electrical equipment and appliances remain connected to the power source even after catching fire or causing a fire, thus still carrying electricity； Secondly, some electrical equipment (such as power transformers, circuit breakers, motor starting devices, etc.) contains oil inside; in the event of a fire, this oil may spray out or even cause an explosion, thereby spreading the fire and expanding its scope. Therefore, appropriate measures must be taken to extinguish electrical fires. 1. Cut off the power supply: In the event of an electrical fire, if the power has not yet been turned off at the scene, the first step should be to find a way to cut off the power supply. This is an important measure to prevent short circuits in electrical equipment and wiring from causing the fire to spread further, as well as to avoid electric shock accidents. When cutting off the power supply, the following points should be noted: ① Electrical equipment in fire areas loses its insulating properties due to moisture and smoke; therefore, reliable insulating tools must be used when turning off switches or cutting off the power supply in other ways, to prevent electric shock accidents during the operation. ②The location where the power is cut off should be chosen carefully to avoid interfering with the fire-fighting efforts. ③In the event of an electrical fire at night, when cutting off the power supply, temporary lighting measures necessary for firefighting and rescue should be considered. ④When cutting wires, wires of different phases should be cut at separate locations to avoid two-phase or three-phase short circuits ； The cutting point of the overhead conductor should be located near a support on the power supply side, to prevent the conductor from coming into contact with people or causing a short circuit after it breaks. ⑤If the wire is under load, the load should be removed as much as possible before cutting off the power supply, to prevent switching off under load. 2. To prevent electric shocks and electrical fires, if, due to an emergency, it is necessary to seize the opportunity to extinguish the fire, or if for other reasons it is not possible to cut off the power supply in a timely manner, then firefighting must be carried out while the electricity is still connected. To prevent electric shock, the following points should be noted: ① The firefighters must maintain a sufficient safety distance from the live electrical components, to avoid direct contact or getting too close to the live electrical appliances, wiring, and equipment, as well as to the fire extinguishers they use. ②When high-voltage electrical equipment or lines become grounded, a safety zone should be established to prevent people from entering and getting electrocuted. Inside, firefighters must not enter an area within 4 meters of the fault site ； Outside, firefighters must not enter an area within 8 meters of the fault site ； Firefighters entering the aforementioned area must wear insulated boots. ③Non-conductive extinguishing agents such as carbon dioxide, dry powder, and dry sand should be used to put out fires. Water and foam extinguishing agents are conductive, so they must not be used when extinguishing fires involving electricity. ④When extinguishing fires with electricity, insulating rubber gloves should be worn. 3. Oil-filled electrical equipment cannot be extinguished with water while it is still under power. ① In the event of a fire on the outside of oil-filled equipment, extinguishers such as carbon dioxide or dry powder extinguishers can be used ； If the fire is large, the power supply should be cut off immediately and water should be used to extinguish it. ②If a fire breaks out inside the oil-filled equipment, the power supply should be cut off immediately. A spray water gun can be used to extinguish the fire, and dry sand, soil, etc. can be used for firefighting if necessary. Spilled oil fires can be extinguished using a foam fire extinguisher. ③When rotating electrical machines such as generators and motors catch fire, to prevent the shafts and bearings from deforming, it is possible to let them rotate slowly, use a water spray gun to extinguish the fire, and assist in cooling them down. Fire can also be extinguished using carbon dioxide, steam, etc.