Generally, fuse and other equipment are installed between the incoming and outgoing wires of the distribution box and its bus. When the outgoing wire is struck by lightning, if the incoming fuse is blown first, all the distribution boxes will lose lightning protection. Every year, there are many The distribution box was damaged by lightning.
3. Improper installation process causes overheating and burning of the connectorSome electricians do not press the wire lug when changing the lead wire, and use a multi-stranded wire to wind the wire lug for screw connection. As a result, the lead wire is burnt shortly after the wire is changed. The distribution box produced by some manufacturers is connected to the bus by the branch line stacking and screw connection, and the heat dissipation is not good, and the heavy load naturally constitutes a continuous failure.
6. Some protective zero-connection power supply systems still use three-phase four-wire power supply. The zero line of the low-voltage power grid is longer and the impedance is large. When the three-phase load is unbalanced, there will be zero-sequence current passing through the zero line. Environmental deterioration, wire aging, moisture and other factors, the leakage current of the wire also forms a closed loop through the neutral wire, which causes the neutral wire to have a certain potential, which is very unfavorable for safe operation.7. The distribution box is too small, the gap between the electrical appliances and the phases is small, and some have no obvious disconnection points, which not only brings danger to the electrician operation, but also makes it impossible to change the fuse in rainy and foggy weather. Work; distribution boxes generally lack phase protection, and accidents that burn out the electromechanical equipment due to lack of phase occur from time to time; some distribution boxes do not use electronic watt-hour meters, and it is impossible to implement remote centralized meter reading; some distribution boxes are closed all year round. Therefore, there is a lack of routine inspection protection.