Popular Science: How Do Electric Fires Occur Every Day?

There are thousands of fires, but every year there is a kind of fire that happens almost every day, and it is all over the world.

What will it be?

According to the statistics of fire big data, the fire caused by "electrical" causes is the answer.

According to statistics, fires caused by electrical causes account for about 40% of all fires and have been on an upward trend in recent years. Therefore, electrical fires cannot be ignored.

What is an electrical fire?

Electrical fire generally refers to the thermal energy released due to faulty electrical lines, electrical equipment, appliances, and power distribution equipment; such as high temperature, arc, spark and non-failure release of energy; such as the hot surface of electric appliances, with Fire caused by igniting a body or other flammable material under burning conditions, including fire caused by lightning and static electricity.

What are the causes of electrical fire?

1. Long service life of electrical lines, aging, poor contact between copper and aluminum wires, lack of normal maintenance, and leakage and ignition, which lead to heat through the line, burning out, and causing fire.

2. When the wire is short-circuited, the current can be increased several times or more than several times normal, and the heat generated is proportional to the square of the current. The temperature of the wire rises sharply when the temperature of the insulation layer exceeds 250 degrees Celsius. The circuit will catch fire, and the situation is proportional to the length of the short circuit wire.

3 , the melting beads when the electrical switch fuse is blown and the sparks generated when the switch is turned off fall on the flammable material below may cause a fire.

4. Electric appliances and lighting fixtures are close to flammable materials when they are used or they are forgotten to cut off the power after they are used up. If they are left on the ignition base or the used heat is not dispersed, they will immediately be put into combustible parcels, which will cause fire.

5 , welding operations, do not take safety measures, so that the arc welding flammable combustible or sparks, slag falling on the flammable material and cause fire.

6. The overloaded operation of electrical equipment and the jamming of the rotating part of the mechanical equipment will cause the overheating of the equipment due to excessive torque.

7. If the power supply voltage is higher than or lower than 15% of the rated voltage , the line current may increase or even dangerous temperature may occur.

8. Circuit breakers, controllers, etc. are operated under abnormal conditions. The strong arc that occurs can easily burn personnel or cause fire. The oil of the oil circuit breaker, power transformer, etc. will be gasified and decomposed in the high temperature arc and will burn or explode.

What are the characteristics of electrical fire?

1 , the seasonal characteristics of electrical fire

Electrical fires often occur in summer and winter.

( 1 ) Summer. In summer, because of the high ambient temperature, the degree of heat generated by electrical equipment has a great influence. If it is not properly managed, it may cause insulation damage and fire. The thunderstorm season is the key season for electrical fire protection. It is very important to do a good job of electrical fire prevention in this season.

( 2 ) Winter. In winter, the weather is cold, windy, windy, dry, long and short, and there are many electrical fires. The overhead lines were affected by the wind, and the conductors collided with the discharge and caught fire. Heavy snowfalls and strong winds caused rod breaks and broken wires. The use of electric stoves, electric heating appliances and other heating, improper use, flammable combustibles cause fire. The air is dry in winter and static electricity causes fire.

2 , the time characteristics of electrical fire

Many electrical fires often occur at night or on holidays and holidays. Before the holiday, holiday or off-duty, due to negligence, people did not properly handle the electrical equipment and power supply, and they rushed away and caused some equipment to run for long periods of time, causing overheating or igniting other flammable materials and causing fire. There are also temporary power outages or other things that leave the equipment and do not shut off the power supply, causing a fire after the power supply is restored. After midnight, the electricity consumption was reduced, the supply voltage was high, and overheating or insulation damage occurred. Often after these fires, it is precisely on festivals, holidays or nighttime that no one is on duty, it is difficult to find them early and it is easy to spread and expand.

3. Severe weather and other natural disasters cause electrical fire

Natural disasters such as heavy rainstorms, mountain torrents, heavy snow tremors, and lightning strikes can cause accidents such as breakages and short lines, leading to fires.

4 , paralysis is the main reason for the occurrence of electrical fire

In addition to the defects in the equipment itself, most of the fires in electrical equipment are due to a small number of people who do not understand the safety of electrical fire protection and are paralyzed. The use of a plurality of jack plug; the fans, televisions, long-term use electric appliances, not cut off the power when persons from; heavy electrical equipment power plug; Luanla random access line, like linker handled properly. This shows that overcoming paralysis and strengthening electrical fire safety inspections. It is very important to understand and master the knowledge of electrical fire prevention and formulate an electrical fire prevention system.

5 , the characteristics of electrical fire combustion

After an electrical fire occurs, the fire can burn along the wires and spread quickly ( especially short circuit ) . The combustion is fierce and can easily ignite combustibles. The insulating layer of the wire is mostly easy to burn, and it can also produce toxic gases when burning.

How to prevent electrical fires?

1. Improve short circuit protection and overload protection, install circuit breakers and leakage protectors;

2 , line laying specifications, reliable connection, wire diameter in line with the requirements;

3 , electrical equipment is in good condition, equipment and power connection is reliable, do not overload the use of electrical equipment;

4 , install and use qualified electrical components and equipment;

5 , regular inspection of insulation properties, electrical component functions and equipment conditions, especially short-circuit protection and overload protection reliability.

How to put out an electrical fire?

From the perspective of fire fighting, electrical fire has two characteristics: First, the electrical equipment is not connected to the power source after it has caught fire or caused a fire. The second is some electrical equipment ( such as power transformers, circuit breakers, and motor starting devices ). It is oil-filled by itself, and when a fire occurs, it may inject fuel or even explode, causing the spread of fire and expanding the scope of fire. Therefore, electrical fire fighting must take appropriate measures according to its characteristics.

1 , cut off the power

In the event of an electrical fire, if there is no power outage on the site, it is first necessary to find ways to cut off the power supply. This is an important measure to prevent the expansion of the scope of fire and the avoidance of electric shock. When cutting off the power supply, please note the following points:

1) Cut off the power supply must use reliable insulation tools to prevent electric shock accidents during operation:

2) The location of the cut off power should be selected properly so as not to affect the fire extinguishing work.

3) When cutting the wire, the non-inverted wire should be cut at different parts to avoid artificial short circuit;

4) If the wire carries a load, remove the load as much as possible before cutting off the power supply.

2 , to prevent electric shock

In order to prevent electric shock during fire extinguishing, pay attention to keeping a safe distance with the electrified body when extinguishing the fire. Do not use water ( as shown ) , foam fire extinguishers. Dry yellow sand and carbon dioxide and dry powder fire extinguishers should be used to extinguish the fire. Prevent the body, hands, feet, or the use of fire extinguishers and other direct electrical contact with part of an electrical part or too close to an electric shock. When carrying out fire extinguishing, insulated rubber gloves should also be provided.

3 , fire extinguishing equipment

When extinguishing an internal fire in an oil-filled device, the following points should be noted:

1) When the outside of the oil-filled equipment catches fire, use a fire extinguisher such as carbon dioxide, 1211 , or dry powder to extinguish the fire. If the fire is heavy, cut off the power immediately and use water to extinguish the fire.

2) If it is a fire inside the oil-filled equipment, immediately cut off the power supply. Use a spray gun to extinguish the fire. If necessary, use sand, mud, etc. to extinguish the fire. The leaked oil fire can be extinguished by a foam fire extinguisher.

3) When the rotary motor such as a generator or a motor catches fire, to prevent the shaft and the bearing from being deformed, it can be made to rotate slowly, use a spray gun to extinguish the fire, and help them cool down. Can also use carbon dioxide, 1211 , steam and other fire.

The information in this article comes from the Internet and was reorganized and edited by China Rescue Equipment Network.