This concerns a molded case circuit breaker having separable main contacts and an operating mechanism utilized to cause the separable main contacts to open and close. A trip unit is provided to actuate the operating mechanism in desirable circumstances. Disposed within the circuit breaker casing is a region for the installation of an auxiliary device, such as a bell alarm device, shunt trip device etc. The case of the auxiliary device has an opening disposed therein through which a movable auxiliary device lever protrude. The opening of the circuit breaker case has a region for interfacing with the operating mechanism of the circuit breaker. A separate lever is disposed between the operating mechanism and the auxiliary device lever member. This separate lever member is driven by the operating mechanism of the circuit breaker and actuates the lever of the auxiliary device. It is pivoted about a protrusion on the auxiliary device.