CIRCUIT BREAKER

PROBLEM TO BE SOLVED: To provide a circuit breaker capable of being used by swapping a leakage tripping unit for an electronic and a thermomotive electromagnetic tripping unit. SOLUTION: In the circuit breaker, wherein a breaker case is composed of a base and a cover and which is formed by unitizing an automatic tripping device of the breaker and housing the device into a recess of the base, the tripping unit of any type of electronic, thermomotive electromagnetic or leakage detective one, has an outer enclosure with the same shape exposing a tripping portion, a terminal conductor and a movable contact side conductor. In the outer enclosure of a leakage detecting type tripping unit 32A, an over current tripping element, a leakage detecting ZCT 34, an amplifying circuit 35 for amplifying an output from the ZCT 34 and a leakage tripping electromagnet portion 36 operating based on the output from the amplifying circuit are housed. COPYRIGHT: (C)2004,JPO