Measuring zero and ground voltages with a multimeter
1, the zero line fire wire connection reversed
This happens, it is possible that the line is messy, there is no color distinction between the wires, or brain dead always think that the left zero right fire caused.
Processing method is simple, since there is a multimeter on hand, using a multimeter to measure the resistance between the three lines, voltage, from the new definition of the three lines which is the fire line, which is the zero line, which is the ground line, and do a good job of labeling, next time you will not make a mistake.
2, the zero line has a broken point
We measure voltage preferably at the power circuit breaker, or if convenient, at the meter. If you measure at the back end of the equipment, there is a possibility that the zero line is broken and a misjudgment occurs.
Zero wire broken at the rear end, then the fire wire and zero wire will be connected through the filament or coil, although there will be some resistance, but basically negligible, the measurement of the voltage does not change much. In this case, we should remove the bulb and other electrical appliances, disconnect the zero wire and fire wire circuit, the measurement will be accurate.
3, the zero line resistance is too large
This situation is basically due to the crimping is not tight, poor contact. However, the voltage measured in this case fluctuates, and the wire street will have a hot phenomenon.
4, the equipment shell charged
If the equipment shell charged, that is, the fire line leakage, the use of ordinary air switches, leakage current does not reach the short-circuit current, the air switch will not trip. In this case, the measurement of the zero line and the ground line may have 220V voltage.
Or although the use of leakage protector, but the ground line is broken or ground resistance is too large. This situation occurs leakage, measurement of zero and ground will also have 220V voltage.
5, ground and fire wire reversed
This kind of oddity is difficult to imagine, but analyzing the problem, we also have to consider, do not let go of any doubt.
