Abstract: An adjustable thermal-magnetic trip unit for a molded case circuit breaker 10 is disclosed, with the circuit breaker 10 including a housing 12 having an operating mechanism 40 including an intermediate latch 52, a line terminal 18, a load terminal 16 and a cover 20. The adjustable thermal-magnetic trip unit includes a magnetic yoke 66 mounted in the housing 12, and a bimetal member mounted in the magnetic yoke 66, with the bimetal member having a fixed end and a movable end. The fixed end is coupled to a load bus 61 of the load terminal 16, and the movable end is coupled to a movable contact of the operating mechanism 40. The trip unit 610 also includes a horizontal trip bar rotatably mounted in the housing 12, with the trip bar 54 having an actuating arm gapped from the movable end of the bimetal member and with the actuating arm aligned to selectively engage the movable end of the bimetal member.

Abstract: A circuit breaker has a pair of poles, either of which can experience a ground fault. A sensing device senses an imbalance of current between the phases and neutral, and a trip device responsive to the sensing device simultaneously trips both of the poles when an imbalance of current (ground fault) is sensed in either of the poles. The trip device includes a trip lever engageable with each of the poles and a single solenoid for controlling operation of the trip lever.

Abstract: A housing is provided for a circuit breaker. The circuit breaker has contacts capable of being in an open state or a closed state, of movement between the open and closed states, and of generating a hot gas in consequence of that movement. An electronics module is provided for controlling movement of the contacts from the closed state to the open state. The housing has a first portion housing the contacts and a second portion housing the electronics module. The second portion is formed of a material subject to damage by the hot gas, and the first portion is constructed to protect the second portion from damage by the hot gas. The first portion is ideally formed of a thermosetting material resistant to damage by the hot gas and the second portion is ideally formed of a thermoplastic material, which reduces the cost of manufacturing the housing. A quick-mounting construction for assembling the second portion with the first portion further reduces the cost of assembly.