1. When using a multimeter to measure leakage, first ensure safety. Turn off the power supply and disconnect all electrical devices to avoid the risk of electric shock.
2. Measure the ground voltage of the electrical equipment enclosure. Switch the multimeter to the AC voltage setting, connect the red probe to the metal casing of the equipment, and ground the black probe. If the displayed voltage is higher than 30V, it indicates that there is an electrical leakage in the equipment; if it is lower than 30V, it is generally considered normal.
3. Measure the leakage current using a clamp-on ammeter. Switch the clamp-on ammeter to the AC current measurement mode, and pass through the live wire and neutral wire simultaneously. Observe the current reading, which represents the size of the leakage current.
4. For the detection of zero-line leakage, set the multimeter to the AC voltage mode and select the appropriate range. Connect one measuring lead to the zero-line socket hole and the other lead to the grounding wire socket hole. Read the voltage value. A value close to zero indicates no leakage, while a significant voltage value may indicate a leakage problem.
5. The power-off measurement method is suitable for non-contact leakage detection. Set the multimeter to the high resistance range (e.g. RX10K), connect one probe to the live wire and the other to the ground. If an infinitely large resistance is displayed, there is no leakage; otherwise, there is leakage.
6. During the measurement with an electrically charged device, set the multimeter to the 250-volt AC voltage range and measure the voltage between the casing of the faulty appliance and the ground. If the voltage is between 30 and 50 volts, switch to the 50-volt range to further confirm. Any voltage above 30 volts is considered leakage, while any voltage below 30 volts is considered normal.
7. Leakage measurement between live wire and neutral wire. After turning off all the electrical appliances in the house, measure the resistance between the live wire and the neutral wire. If the result is infinity, it indicates a leakage phenomenon; otherwise, it means there is a leakage problem in the circuit.

   

Through these steps, one can effectively determine whether there is a leakage issue in the circuit.