What could be the cause of an electrical fire?

The possible causes of electrical fires are as follows:

1. Leakage. If the wire is used for too long, the line may deteriorate or the insulation capacity of the wire insulation skin will be weakened, resulting in leakage current beyond the normal range between the wire and the wire or between the wire and the ground.

The contact resistance at the leakage point accumulates over time.

Increasing resistance can cause the wire to heat up.

It is very easy for the temperature to be too high and ignite the surrounding combustibles. When the leakage phenomenon is serious, there is also a risk of electric sparks, which is very easy to cause electrical fires.

2. Short circuit. Breakage of the conductor insulation may cause the line to be shorted, such as phase wires.

Occasionally, the phase wire is in direct contact with the neutral wire and the ground wire, so that the resistance decreases, the current increases sharply, and the temperature of the line and the surrounding environment will also rise instantaneously. In addition to igniting the short circuit point of the insulation layer of the line, the heat of the wire can also cause a faulty arc to ignite the surrounding combustibles and cause an electrical fire.

3. Overload.

If the circuit breaker and wire cross-section selected during the design are unreasonable, or the line exceeds the rated current carrying capacity.

will cause a continuous increase in the temperature of the wire. When the overload phenomenon is severe, it may cause the insulation layer of the wire and the objects around the wire to burn, causing an electrical fire. Overload will also accelerate the aging of the wire insulation and cause short-circuit faults.

4. The contact resistance is too large.

The contact resistance is the resistance that is formed at the joint, and if the contact is good and the contact resistance is small, it will produce less heat and maintain a normal temperature. However, there are often problems such as poor welding and impurities at the contact points, which makes the contact resistance too large and causes the joint to heat up, which may cause electrical fires.

There are many reasons for electrical fires, among which overtemperature, overload, short circuit, and leakage are the main causes.

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There are three possible causes of an electrical fire:1. Leakage.

When the leakage occurs, the leakage current will flow into the earth on the way, if it encounters a part with a large resistance, it will produce a local high temperature, causing the nearby combustibles to catch fire, thus causing a disaster. In addition, the leakage spark generated at the leakage point will also cause disaster.

2. Short circuit: due to the sudden decrease of resistance and the sudden increase of current during short circuit, the instantaneous heat generation is also very large, which greatly exceeds the heat generation of the normal operation of the line, so that the insulation layer burns rapidly, and can melt the metal, causing the burning of nearby flammable combustibles and causing fire.

3. Overload:

When the conductor is overloaded, the aging and deterioration of the conductor insulation layer is accelerated. When severely overloaded, the temperature of the wire will continue to rise, and even cause the insulation of the wire to burn, and can ignite the combustibles near the wire, thus causing a fire.

Leakage, overtemperature, short circuit, and overload are all major causes of electrical fires.

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Causes of electrical fires.

Analyzing the past electrical fires, there are mainly the following reasons: one is a short circuit. In the event of a short circuit in an electrical circuit, the corresponding branch load is removed.

The current is inversely proportional to the change in the impedance of the load, when the impedance tends to be very small. The current is high and can generate high temperatures at the point of short circuit. At this time, if the protection device cannot be instantaneously disconnected from the faulty branch.

Wire insulation materials and surrounding combustibles will be followed by fire.

The second is poor contact. At the connection or docking of electrical wiring, if there is contact slack at the contact, the voltage between the contacts is sufficient to break through the air gap. An electric arc is formed in the gap, and sparks burst out, enough to ignite nearby combustibles to form a fire.

Third, the design load is small, and the residential buildings before the nineties were in electrical design. The rapid development of the economy is not fully considered, and only ordinary lighting and general household appliances are generally considered, and the margin left by the load design of the entire electrical circuit is small, or even not left. After the 90s, many buildings were renovated in order to be beautiful and comfortable.

But the electrical wiring was not replaced. As a result, the electrical circuit has been in or is on the verge of overload operation for a long time, which will not only cause the electrical circuit to overheat, but also increase the contact resistance at the joint part of the electrical circuit, and the circuit has been concealed during decoration. The joints of the wires are more hidden in the dark, and it is difficult to find them during ordinary inspections.

Fourth, it is the improper selection of conductor connection mode. Found during fire prevention inspections or investigations into the cause of fires. In some large buildings, copper wires are used for electrical wiring and distribution trunks, while aluminum wires are used at the ends.

And the connection method is copper and aluminum direct connection, and the connection is under the action of air. Copper-aluminum contact electroerosion is prone to occur, and the joints that have been in operation for a long time will naturally loosen under the electro-erosion, resulting in a large contact resistance, resulting in local heat release or ignition discharge, igniting the surrounding combustible materials and causing fire.

Fifth, the reliability of conductor insulation is low. In humid environments, whether neoprene insulation, PVC insulation or insulation of cotton fabrics. If the humid air produces an acidic or alkaline environment around the conductor, it can cause the insulation layer to age and damage rapidly, resulting in line leakage or short circuit; If a conductor is short-circuited due to moisture in the insulating material in the strong current control system, it will cause the system to malfunction.

When the running circuit is equipped with electric heating, it can cause a fire. In addition, the use of insulating materials does not meet the requirements of the product standard in itself. The physical and mechanical properties are not up to the requirements, and the electrical properties are extremely poor.

It is also very easy to lead to insulation and voltage breakdown, resulting in fire.

In addition, there are external ignition sources that ignite electrical wiring, resulting in short circuits in the wires; Short-circuits in wires caused by rats biting through electrical insulation materials also occur from time to time.

The main causes of electrical accidents are: 1. Problem analysis and answer: The main causes of electrical accidents are operation errors, substandard maintenance quality, equipment failure, poor wire contact, aging of electrical equipment, etc.

Electrical fires: Fires caused by electrical wiring.

The cause of electrical fire may be overload, resulting in overheating of electrical circuits, ignition caused by poor contact, ignition caused by leakage caused by skin damage, and electrical short circuit can also cause electrical fire.

The cause of electrical fire may be due to aging lines, overload operation, short circuit, etc.

Instantaneous voltage is too high, circuit aging, short circuit ignition...

Basically, there are many electrical fires caused by interphase short circuits or aging electrical equipment.

It may be a short circuit in the wire, or the wire is aging, overloaded, and the electrical equipment is unqualified.

Aging wires, poor contact, overloaded operation.

1. Leakage.

The so-called leakage is that a certain place of the line due to some reason (natural or man-made reasons, such as wind and rain, humidity, high temperature, pressure, scratching, friction, corrosion, etc.) makes the insulation ability of the wire or bracket material decrease, resulting in a part of the current passing between the wire and the wire, between the wire and the earth, this phenomenon is leakage.

2. Short circuit.

After the insulator of the bare wire or insulated wire in the electrical circuit is damaged, the live wire and the neutral wire, or the live wire and the ground wire (including the grounding subordinate to the earth) meet together at a certain point, causing a sudden large increase in the current The phenomenon is called short circuit, commonly known as touching the wire, mixing the wire or connecting the electricity.

3. Overload.

The so-called overload means that when the amount of current passing through the wire exceeds the safe current carrying capacity, the temperature of the wire continues to rise, which is called wire overload.

4. The contact resistance is too large.

On the electrical circuit with a large current flowing, if there is a phenomenon of excessive contact resistance somewhere, it will generate great heat in the local range of excessive contact resistance, which will discolor the metal or even melt, causing the insulation layer of the wire to burn.

Precautions against electrical fires:

1. Improve the safety quality of electrical staff, so that they understand the safety requirements of electrical devices in the process of installation, use and maintenance.

2. The design of electrical equipment and circuits should be reasonable, the installation should be reliable, the use should be compliant, the maintenance should be timely, and the fire hazards should be eliminated immediately.

3. The electrical circuit should not be overloaded, and the large-load equipment should not be arbitrarily added to the original design line, and the aging line should be updated. The power cord of the mobile device should be a rubber cord.

4. The use of electric heating equipment, lighting fixtures and electric welding should be consistent with the safety distance of flammable materials. After the electric heating appliances are used up, the power should be cut off in time, and the residual heat should be dissipated before storage.

5. Pay attention to the fluctuation of power supply voltage when the equipment is running. If the voltage is unstable for a long time, voltage stabilizing equipment should be used. The motor is indispensable for phase operation.

Overloads, short circuits, arcs and sparks,Poor contact.

An overload is when the power and current of an electrical device or wire exceeds its rated value. Overload converts the electrical energy in the conductor into heat energy, and when the conductor and insulator are partially overheated and reach a certain temperature, it will cause a disaster.

Short circuits are one of the most serious fault states in electrical equipment. In the event of a short circuit, an arc or spark is generated at the point of the short circuit or at the joint where the wire connection is loose. The arc temperature is very high, up to more than 6000 meters, and can ignite not only its own insulation, but also the combustible materials, vapors and dust in its vicinity.

Precautions for preventing electrical fires.

In order to prevent arc grounding short circuit, the use of circuit breaker with leakage protection function should be vigorously promoted, as far as the general building is concerned, in addition to the 30mA leakage protector (RCD) installed at the end of the line, the three-phase circuit breaker with leakage protection function should be installed at the incoming line, and the leakage action current can be selected 300mA or 500mA with a second delay.

The circuit breaker with leakage protection function can be used with the second stage of 30mA RCD to achieve selective protection, and the arc energy below 500mA is not enough to ignite**, which can effectively eliminate the fire hazard caused by the current large number of arc ground short circuits.

Overload, overtemperature, short circuit, and leakage can all cause electrical fires.

At home, in a residential building or in a school, the company can install a smart power protector, which can monitor the safety at any time through a mobile phone.

Causes of electrical fires: aging lines, overload operation, poor quality, private connections, poor heat dissipation, heating of equipment joints, and high temperature.

1. The line is aging and overloaded.

With the arrival of high temperature weather, air conditioners, refrigerators, electric fans and other electrical equipment have increased significantly, and the aging of the line and overload operation have caused short circuits due to damage to the insulation skin of the power supply**.

2. Poor quality.

Improper installation or operation of electrical equipment, poor quality of installed electrical appliances, this situation is prone to electrical accidents!

3. Privately pull and pick up.

Violating safety regulations and connecting wires without permission, or not knowing the common sense of safe electricity use are also important causes of electrical fires.

4. Poor heat dissipation.

Poor heat dissipation of electrical appliances or motors, high temperature reduces dielectric strength, short circuit occurs or the motor burns out and catches fire. Summer is also a frequent period of automobile fires, and under the conditions of hot temperature, the slightest negligence in the production, transportation and storage of chemical dangerous goods will cause fires.

5. The equipment joint is heated.

Some electrical equipment, such as transformers, motors, capacitors, wires and connectors, etc., will cause disasters when the heating temperature rises during operation.

6. High temperature.

Hot weather tends to form strong convective weather, which increases the speed of fire development and spread. In summer, the high temperature is hot, the precipitation is less, the evaporation is large, the weather is dry, the ignition point is reduced, and the fire is easy to burn when it encounters an open flame, and the fire will spread to the adjacent buildings under the action of radiant heat, forming a three-dimensional or large-scale fire.

Ways to prevent electrical fires

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

2. The line laying is standardized, the connection is reliable, and the wire diameter meets the requirements of use.

3. The electrical equipment is in good condition, the equipment is connected to the power supply reliably, and the electrical equipment is not overloaded.

4. Install and use qualified electrical components and equipment;

5. Regularly check the insulation performance, the function of electrical components and the condition of the equipment, especially the reliability of short-circuit protection and overload protection.