1、 Leakage fire

The so-called leakage refers to a situation where the insulation or support material of a wire decreases due to certain reasons (natural or human factors, such as wind, rain, humidity, high temperature, pressure, scratches, friction, corrosion, etc.), resulting in a portion of the current passing between the wire and the wire (through damaged insulation, support, etc.), or between the wire and the earth (through reinforced concrete walls, tin sheets, etc.). This phenomenon is called leakage. When leakage occurs, the leaked current flows into the ground. When encountering areas with high resistance, it will generate local high temperatures, causing nearby combustibles to catch fire and cause a fire. In addition, sparks generated at the leakage point can also cause fires.

2、 Short circuit fire

The phenomenon where the insulation of bare or insulated wires in electrical circuits is damaged, and the live wire collides with adjacent wires, or the live wire collides with the ground wire (including grounding belonging to the earth) at a certain point, causing a sudden and significant increase in current is called a short circuit, commonly known as wire collision, mixed wire, or electrification. Due to the sudden decrease in resistance and sudden increase in current during a short circuit, the instantaneous heat generation is also very large, greatly exceeding the heat generation during normal operation of the circuit. Strong sparks and arcs are easily generated at the short circuit point, which can not only cause rapid combustion of the insulation layer, but also melt the metal, causing nearby flammable and combustible materials to burn and cause a fire.

3、 Overload fire

The so-called overload refers to the phenomenon where the temperature of the wire continuously rises when the current passing through the wire exceeds the safe current carrying capacity, and this phenomenon is called wire overload. When the wire is overloaded, it accelerates the aging and deterioration of the wire insulation layer. When severely overloaded, the temperature of the wire will continue to rise, and even cause the insulation of the wire to burn, which can ignite combustibles near the wire and cause a fire.

4、 Fire caused by excessive contact resistance

As is well known, wherever wires are connected to wires, wires to switches, fuses, instruments, electrical equipment, etc., there are joints, and the resistance formed on the contact surface of the joints is called contact resistance. When there is current passing through the connector, it will generate heat, which is a normal phenomenon. If the joint is well handled and the contact resistance is not high, the heating at the joint point will be minimal and normal temperature can be maintained. If there are impurities in the joint, the connection is not secure, or other reasons cause poor contact of the joint, resulting in excessive local resistance at the contact area. When current passes through the joint, a large amount of heat will be generated here, forming high temperature. This phenomenon is called excessive contact resistance. In electrical circuits with high current passing through, if there is a phenomenon of excessive contact resistance in a certain area, it will generate great heat within the local range of excessive contact resistance, causing the metal to change color or even melt, causing the insulation layer of the wire to burn, and igniting nearby combustibles or dust, fibers, etc. accumulated on the wire, thereby causing a fire.

The above is the list of possible causes of electrical fires compiled by Siemens electrical fire alarm system manufacturers for you. We hope that through the knowledge above, you can be alert to these situations that may cause fires