Abstract: A molded case circuit breaker is taught with a housing base and a primary cover disposed on the housing base. The primary cover has a recess therein for an auxiliary module which is disposed in the recess. A secondary cover is disposed on the primary cover for covering the recess when the auxiliary module is disposed therein. A combination manual trip and secondary cover interlock is provided which is accessible from outside of the secondary cover for manually opening separable main contacts or for automatically opening separable main contacts when the secondary cover is removed. There is also provided on the back plane of the housing a single piece DIN rail attachment for securing the back plane to a DIN rail. There is provided an under voltage release mechanism for actuating the circuit breaker to trip on the occurrence of an under voltage condition of predetermined magnitude across the lines served by the circuit interrupter.

Abstract: A molded case circuit breaker is taught with a housing base and a primary cover disposed on the housing base. The primary cover has a recess therein for an auxiliary module which is disposed in the recess. A secondary cover is disposed on the primary cover for covering the recess when the auxiliary module is disposed therein. A combination manual trip and secondary cover interlock is provided which is accessible from outside of the secondary cover for manually opening separable main contacts or for automatically opening separable main contacts when the secondary cover is removed. There is also provided on the back plane of the housing a single piece DIN rail attachment for securing the back plane to a DIN rail. There is provided an under voltage release mechanism for actuating the circuit breaker to trip on the occurrence of an under voltage condition of pre-determined magnitude across the lines served by the circuit interrupter.