Circuit breaker with adjustable thermal trip unit

A circuit interrupter trip unit comprising a circuit breaker mechanism having separable contacts adapted to be connected as part of a distribution system, the circuit breaker mechanism comprising a releasable member movable when released from a latched position to effect opening of the contacts, a trip bar movable to a tripped position to effect release of the releasable member and being biased in the latched position, a stationary magnetic structure of each conductor of the distribution system and comprising a coil and core assembly and movable in response to excessive overload currents, a lever armature associated with each stationary magnetic structure and operatively connected to the trip bar for moving the trip bar to the unlatched position, an elongated bimetal movable in response to overload currents to effect movement of the trip bar to the unlatched position, and adjustable means on the trip bar for increasing and decreasing the amount of movement of the trip bar required for releasing the releasable member.