US Patent 7167349 Earth leakage breaker

An earth leakage breaker includes a main contact, a switch mechanism, an operating handle, a leakage tripping device and an over-current tripping device having an earth-leakage-detection circuit disposed in a main-body case. A power-supply line connects the earth-leakage-detection circuit to the main circuit for supplying voltage between phases of the main circuit as a power source of the earth-leakage-detection circuit. Further, a test switch is provided for turning on and off a power-supply circuit of the power-supply line connected to the earth-leakage-detection circuit, and an operation of the test switch is linked to an ON/OFF operation of the switch mechanism.