A simple way to use a multimeter to measure whether the circuit is leaking
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.
As for using a resistor to measure circuit leakage, I don't think it's 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 indicate the insulation situation between them. That is to say, the insulation resistance is completely different between 9V and 220V. So the measurement of insulation resistance is always carried out at a voltage higher than the applied voltage to obtain reliable data. So a shaking table must be used.
Of course, if you are only testing for a short circuit or path between the live wire and the protective ground, you can also use a multimeter with a resistance switch. Just can't measure the insulation data between them.
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.
