How to Measure 220v Line Leakage with Multimeter
The problem of measuring 220V leakage with a multimeter is not suitable, because what you want to measure is the leakage current. The multimeter is weak in measuring weak AC current, and it is troublesome to measure it inaccurately.
If you suspect that the circuit is leaking, you can use a circuit breaker with a leak protection to judge, judge the range of the leakage segment by segment, and troubleshoot.
As for using electricity to block the leakage of the measurement line, I don't think it is appropriate. Because since it is a leakage, the resistance between the live wire and the protective ground is not infinite, but the voltage of the multimeter is not enough to explain the insulation between them, that is to say, the insulation resistance at 9V is completely different from that at 220V. Therefore, the insulation resistance is measured at a condition higher than the electrical voltage to obtain reliable data. So you have to use a shaker.
Of course, if you just test whether there is a short circuit or a path between the live wire and the protective ground, it is also possible to use a multimeter to block it. Just can't measure the insulation data between them.
Strictly speaking, a megger should be used to measure whether the line insulation resistance circuit is leaking or not. The megger is equivalent to a 1000v or 500v generator. The leakage current passes through the sampling resistor inside the megger, and a sampling voltage indication is generated on the resistance. Under normal circumstances, a stable value greater than 0.5 megohm is qualified. The battery inside the multimeter is 9v to 15v. The resistance and voltage files can only determine the short circuit, and roughly judge whether there is leakage.
1. Power-off measurement: turn off and disconnect all electrical appliances, use a multimeter with RX10K gear, one test lead is connected to the live wire, and the other test lead is grounded (or faucet). It should show infinite resistance, otherwise there will be leakage.
2. Live measurement: use a multimeter with 250 volts of AC voltage to measure the metal shell of the electric appliance that is suspected of leakage. One test lead is connected to the shell, and the other test lead is grounded (or the faucet). When the pointer shows that the voltage is higher than 30-50 volts, switch to AC 50 volts.
3. Leakage measurement between live wire and neutral wire (or live wire and live wire): turn off and disconnect all electrical appliances, measure the resistance between live wire and neutral wire, it should be infinite, otherwise it is leakage.
The accuracy rate of the above method for troubleshooting is 99.9%, which is convenient, fast and practical. The megohm special shaker is only used in engineering, and the use efficiency is low during maintenance. Only when the multimeter is confirmed to be good, but the line does leak, the shaker is used, but the leakage cannot be detected by the multimeter.
