A simple way to do a leak test on a circuit with a multimeter is this.
The simplest way to measure whether a 220V circuit is leaking electricity with a multimeter is to first cut off the power, set the multimeter to the resistance range (500 ohms), and connect the neutral and live wires to the ground wire with two multimeter pens. If the measurement result is 0, then it can be determined that the wire is grounded, indicating leakage.
To accurately measure whether a 220V line is leaking, a 500V or 1000V megohmmeter should be used. It is not appropriate to use a multimeter to measure whether a 220V line is leaking. If there is no megohmmeter on hand, a normally used bipolar leakage circuit breaker can be temporarily installed at the beginning of the suspected leakage line for testing. If the leakage circuit breaker is connected and closed immediately, and its reset button protrudes (indicating that if the reset button does not protrude, it is overload protection and short circuit protection disconnection), it proves that there is leakage in the line. This method is relatively simple and accurate.
The issue of measuring 220V leakage with a multimeter is not very suitable because you are measuring leakage current, and measuring weak AC current with a multimeter is a weak point. It is also difficult to make accurate measurements. If you insist on measuring, you need to use a current transformer. It is better to use a clamp meter to measure, but you should choose a clamp meter with a suitable range and better sensitivity.
Suspecting circuit leakage, one can use a circuit breaker with leakage protection to determine the range of leakage step by step and eliminate the fault.
If the insulation of the circuit is damaged, it can be visually observed and can be dealt with later. Another situation is that the rolled leather is not damaged, but only slightly cracked, resulting in some grounding in damp conditions, or the damaged area is very hidden and cannot be seen directly by the naked eye. At this point, you can cut off the power to the line and shake it directly with a multimeter. For low-voltage circuits, a 500 volt shaker should be used. For ground measurement, if the insulation is less than 0.5 megohms. It can be considered that the insulation is not very good and should be checked section by section. One thing to note is that when measuring with a shaking table, no electrical appliances should be connected to the circuit. Otherwise, the measured values may be inaccurate.
If a multimeter is used to check for electrical leakage. Maybe not quite accurate. Because the voltage of the meter is usually very low. Only when the leakage is severe can it be detected.
One more thing beyond the topic is that it is best to use residual current device switches for household sockets. In this way, once leakage occurs, the power can be quickly cut off to ensure personal safety.
1. Power off measurement: Turn off and disconnect all electrical appliances, use a multimeter RX10K gear, with one probe receiving the live wire and the other probe grounded (or faucet). The resistance should show infinite, otherwise there will be leakage.
2. Live measurement: Use a multimeter with a voltage range of 250 volts AC to measure the metal casing of the electrical appliance suspected of leakage. Connect one probe to the casing and the other probe to ground (or tap). When the pointer displays a voltage between 30-50 volts, switch to the AC 50 volt range. If the power supply confirms that it is leakage above 30 volts and normal below 30 volts, then swap the zero and fire power supply plug wires and measure again to confirm.
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, which should be infinite, otherwise it is leakage.
