The correct name of the leakage switch is residual current protector, which is an air circuit breaker with special protection function (leakage protection). In addition to the basic functions of an air switch, the air switch can quickly turn off the switch when the load circuit leaks to avoid personal injury and adverse effects on electrical equipment when the load circuit leaks. Generally, the air switch is used as the main switch in the circuit, and the leakage switch is used as the branch switch, so the usual wiring method should be to connect the air switch first, and then the leakage switch.