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There are many common causes of fires caused by wire faults. Below is a brief description of the main causes and preventive measures of electrical circuit fires.

1、 The main reasons for wire fires are:

(1) Circuit short circuit. The so-called short circuit is when two wires of an AC circuit come into contact with each other, and the current does not pass through the electrical equipment in the line, but directly forms a circuit. Because the resistance of the wire itself is relatively small, if only passing through the wire loop, the current will increase sharply, tens or hundreds of times larger than normal. Such a large current flowing through such a thin wire, the greater the resistance, the more heat is generated, which can cause the wire to generate temperatures of thousands of degrees Celsius in a short period of time, enough to ignite nearby combustibles and cause a fire. Line short circuit is caused by long-term use of transmission lines, where the insulation layer ages, cracks, and loses insulation, resulting in collisions between two wires; Or if the wires are randomly connected, the "protective sheath" of the wires may be mechanically damaged, causing a short circuit.

(2) Poor contact. Due to poor wire connectors, the contact resistance of the circuit is too high, causing heating and fire. All circuits have connectors, or wires connected to each other, or wires connected to switches, safety devices, or appliances. If these connectors are not properly connected, they will hinder the flow of charges in the wires and generate a large amount of heat. When the heat is sufficient to melt the insulation layer of the wire, the insulation layer will ignite and ignite nearby combustibles.

(3) Line overload. A wire of a certain material and cross-sectional area has a certain safe current carrying capacity. If the current passing through the wire exceeds its safe current carrying capacity, the wire will generate heat. The more, the greater the heat generation. When the temperature of the wire exceeds 250 ℃, the rubber or plastic insulation layer of the wire will catch fire. If the "sheath" of the wire is damaged, it can also cause a short circuit and increase the risk of fire. In addition, if non-standard fuses are used, the overload situation of the circuit cannot be detected in a timely manner, and the hidden danger will become a reality.

(4) Line leakage. Due to the poor insulation performance of the wire insulation layer or its supporting material, a small amount of current flows between wires or between wires and ground. People often say that running or running is a serious water leakage phenomenon. When the leakage is severe, sparks and high temperatures may also become sources of ignition.

(5) Electric sparks and arcs. Electric spark is the result of discharge between two poles; The arc is composed of a large number of dense electric sparks, and the temperature can reach over 3000 ℃. When the overhead bare wire is shaken by wind, or when tree branches are knocked, or when a vehicle is suspended or scratched, two wires come into contact with each other, discharge occurs, producing electric sparks and arcs. In addition, sparks and arcs can occur at insulation wire leakage, breakage, short circuit points, grounding points, and loose connections. If these electric sparks and arcs fall on flammable and combustible materials, they may cause a fire.

(6) The cable caught fire. The reason for cable burning is that it protected the lead sheath from damage during cable laying; Or the insulation of the cable is mechanically damaged during operation, causing the insulation between the cable cores or between the cable cores and the lead sheath to be damaged, resulting in arcing and burning of the jute protective layer of the cable insulation material; Or due to long-term overload of the cable, the insulation performance of the cable may be reduced or even lost, resulting in insulation breakdown and burning of the cable; Or because the three core cable is used as a single core cable, eddy currents are generated, causing the lead and aluminum sheets to heat up or even melt, resulting in cable burnout.

2、 Measures to prevent circuit fires

(1) Install the circuit as required. Electrical wiring must be installed strictly in accordance with electrical installation regulations, and specialized electricians must be hired for wiring. Electricians must hold a certificate to work.

(2) Choose the correct circuit. According to the actual needs of work and life, the load may lead to the selection of appropriate circuit specifications. Do not be tempted to use wires that are too thin or of poor quality. When selecting wires, pay attention to checking whether they are qualified products.

(3) Safe use of electrical wires. The installed electrical circuits shall not be randomly pulled, connected or added to electrical equipment, which increases the electrical load of the entire circuit. Pay attention to understanding the maximum load of the circuit used, and do not exceed this limit during use, otherwise accidents may occur.

(4) Regularly check the circuit. It is necessary to insist on regular inspections and ask specialized electricians to help check the circuit every once in a while. If the insulation is damaged, it should be repaired in a timely manner. The service life of wires is generally 10 to 20 years. If you find yourself over age, be sure to replace it in a timely manner.

(5) Choose a safe electrical switch. To choose an air switch with a relatively high safety factor, try not to use a knife switch. The knife switch generates electric sparks when switching, which can easily cause danger. Air switches can be used to protect power sources. When using fuses, please choose the appropriate fuse to avoid malfunctions. When the current increases, it can be cut off in time.