If there is no leakage and the line is tightened, the neutral line burns badly, then the neutral line return current is too large! For example, on the same working circuit, when installing wires, several live wires will be pulled to various devices, while the neutral wire only shares one. In the working circuit, the neutral wire and the live wire bear the same current. Therefore, in the working circuit of the equipment, the currents of several live wires return to a neutral wire. If the cross-sectional area of the neutral wire is large enough, it will be fine. If the cross-sectional area of the neutral wire is not large enough, the neutral wire will generate heat. , The connection point of the neutral line is easy to burn out.
There is current in the neutral line of the three-phase circuit. Use a current caliper to check whether the neutral line is a little flowing!
There is current proof: the neutral point drifts! Then measure whether the total neutral line in the distribution box in front of the small distribution box has current three-phase imbalance causing the neutral point to drift!