Short circuit: disconnect the power supply and measure the resistance. When the resistance is very small or even 0, it is a short circuit (metallic short circuit);

Leakage: connect the power supply and measure the voltage of the shell to the ground. When the voltage value is large, it is leakage; Measure the current difference between live wire and neutral wire. If it is not 0, it will leak.

1. Summary

2. multimeter to determine short circuit (220V circuit, for example)

(1): Disconnect the circuit power supply.

(2): Cut off the circuit breakers of each branch of the circuit.

(3): Measure the resistance between the live wires of the trunk line. If the resistance is 0, a short circuit (metal Xing short circuit) will occur in the trunk line.

Note: When it is determined that there is a short circuit in the main road, continue to measure the resistance between the terminals of other equipment on the main road. Determine the short-circuit points in turn.

(4): According to the same method as the trunk, find out whether there is a short circuit point in each branch.

Note: it is difficult to determine the short-circuit fault point of the circuit, but as long as we follow the circuit drawings,

3. multimeter to determine the open circuit (220V circuit, for example)

When the voltage of an element to ground is 0, it means that there is an open circuit before it, and continue to look up.

4. multimeter to determine the leakage (220V circuit, for example)

Turn on the power supply of the circuit, and pass the neutral live wire of the main line side by side through the clamp ammeter. If there is no leakage, the current is zero. If there is leakage, the current is not 0.