Measure the voltage of neutral line and ground line with multimeter.
1, the zero line fire line is reversed
This may happen because the lines are messy, the wires have no color distinction, or because the brain always thinks that the fire is left and right.
The processing method is also simple. Since you have a multimeter at hand, measure the resistance and voltage between the three wires with the multimeter, redefine which of the three wires is the live wire, which is the zero wire and which is the ground wire, and mark it well, so you won't make mistakes next time.
2, the zero line has a breakpoint
We'd better measure the voltage at the power circuit breaker, and if it's convenient, we'd better measure it at the electricity meter. If it is measured at the back end of the equipment, the zero line may be broken and misjudged.
The zero line at the back end is broken. At this time, the live wire and the zero line will be connected through the filament or coil. Although there will be some resistance, it can be basically ignored, and the measured voltage changes little. In this case, it is necessary to remove the light bulb and other electrical appliances and disconnect the loop between the zero line and the live line, so that the measurement will be accurate.
3. The neutral resistance is too large.
This kind of situation is basically caused by tight pressure connection and poor contact. However, in this case, the measured voltage is erratic, and there will be a hot phenomenon at the street of the wire.
4, the equipment shell is charged
If the equipment shell is charged, that is, the live wire leaks, and the common air switch is used, the air switch will not trip if the leakage current does not reach the short-circuit current. In this case, it is possible to measure the zero line and ground line with a voltage of 220V V.
Or even though a leakage protector is used, the ground wire is broken or the grounding resistance is too large. In this case, leakage occurs, and the measuring zero line and ground wire will also have a voltage of 220V V.
5. Ground wire and live wire are connected reversely.
Although this wonderful work is hard to imagine, we have to consider it when analyzing the problem, and don't let go of any doubt.
