Use a multimeter to measure the voltage of the zero line and the ground line
What happens if the neutral wire and the ground wire are reversed? Is the neutral wire connected to the ground wire? What is the voltage between the neutral wire and the ground wire?
In the TN-S power supply system, the neutral wire and the ground wire are both rooted from the same root, and are drawn from the neutral point ground of the transformer. One participates in the working circuit, which is called the working neutral wire, and the other serves as the protection circuit, called the protective zero wire. .
1. The neutral and live wires are reversed
When this happens, it may be that the wiring is messy, the wires are not colored, or the brain always thinks that it is caused by left zero and right fire.
The treatment method is also simple. Since you have a multimeter at hand, use the multimeter to measure the resistance and voltage between the three wires, redefine which of the three wires is the live wire, which is the neutral wire, and which is the ground wire, and mark it well. You won't make a mistake once.
2. The zero line has a breakpoint
It is best to measure the voltage at the power circuit breaker, and if it is convenient, it is best to measure it at the ammeter. If it is measured at the back end of the equipment, the zero line may be broken and a misjudgment may occur.
The neutral wire at the back end is broken. At this time, the live wire and the neutral wire will be connected through the filament or coil. Although there will be some resistance, it can basically be ignored, and the measured voltage will not change much. In this case, it is necessary to remove the light bulb and other electrical appliances, and disconnect the loop of the neutral wire and the live wire, so that the measurement will be accurate.
3. The zero line resistance is too large
This situation is basically caused by loose crimping and poor contact. However, in this case, the measured voltage is erratic, and there will be heat and heat on the street of the wire.
4. The shell of the device is charged
If the case of the equipment is electrified, that is, the live wire leaks, and an ordinary air switch is used, the leakage current does not reach the short-circuit current, and the air switch will not trip. In this case, there may be 220V voltage when measuring the neutral wire and the ground wire.
Or although the leakage protector is used, the ground wire is open or the ground resistance is too large. In this case, leakage occurs, and the measured zero line and ground line will also have 220V voltage.
5. The ground wire and live wire are reversed
Although this kind of weirdness is hard to imagine, we have to consider it when we analyze the problem, and don't let go of any doubts.
