Distribution box in our working life plays a very important role, it plays a role in the control of our lives, but once the fire not only affect our normal work and life, Distribution Box but also a threat to our lives and property , So ahead of the understanding of the distribution box fire causes and precursors, will help us to prevent the occurrence of fire distribution box, then introduce the cause of the distribution box fire, and the distribution box fire precursor.
1, leakage fire: the so-called leakage, that is, Distribution Box a line of a place for some reason (natural or man-made reasons, such as wind and rain, wet, high temperature, Distribution Box pressure, scratch, friction, corrosion, etc.) Or the insulation of the scaffold material, resulting in a part of the current passing between the wire and the wire (through the damaged insulation, the bracket, etc.), between the wire and the earth (the wire through the steel wall of the steel, tinplate, etc.) Leakage.
When the leakage occurs, the leakage of current in the way into the earth, Distribution Box in the case of large parts of the resistance, there will be local high temperature, resulting in near the combustible fire, causing a fire. In addition, leakage leakage generated at the point of leakage, the same will cause a fire.
2, short-circuit fire: electrical lines in the bare wire or insulated wire insulator damage, the line of fire and the adjacent line, or line of fire and ground (including grounding subordinate to the earth) at a certain point together, causing a sudden increase in the current phenomenon Called short-circuit, Distribution Box commonly known as the line, mixed or connected.
Due to a sudden reduction in short-circuit resistance, the sudden increase in current, the instantaneous heat is also great, much higher than the normal work of the line heat, and short-term point easy to produce a strong spark and arc, not only to make the insulation layer Burning, but also make the metal melt, Distribution Box causing the nearby flammable combustible combustion, resulting in a fire.
3, overload fire: the so-called overload is when the wire through the current exceeds the safe current carrying capacity, the wire temperature continues to rise, Distribution Box this phenomenon is called the wire overload.
When the wire overload, the wire insulation to speed up the aging deterioration. When a serious overload, the wire will continue to increase the temperature, and even lead to the insulation of the wire burning, and can ignite the wire near the combustible, resulting in a fire.
4, the contact resistance is too large fire: As we all know: all wires and wires, wires and switches, fuses, meters, electrical equipment, etc. Distribution Box have a connection where the connector surface in the formation of resistance called contact resistance. When the current through the joints will be fever, this is a normal phenomenon. If the joint is handled well and the contact resistance is not large, Distribution Box the heat of the joint point is small and the normal temperature can be maintained.
If the connector has impurities, the connection is not reliable or other reasons to make the joints bad contact, resulting in contact parts of the local resistance is too large, Distribution Box when the current through the connector, it will produce a lot of heat here, the formation of high temperature, this phenomenon is contact The resistance is too large.
In the electrical circuit with a larger current through, Distribution Box if there is a phenomenon in which the contact resistance is too large at some place, it will produce great heat in the local area where the contact resistance is too large to discolor or even melt the metal, Distribution Box causing the wire Of the insulation layer of combustion, and ignite the combustion of nearby fuels or wires on the accumulation of dust, fiber, etc., resulting in a fire.