Abstract: A circuit breaker mechanism has a contact arm (56) forming a portion of an interruptable load current path through the circuit breaker and mounted with respect to a pivot (110) for swinging motion to break the current path. A spring-loaded, over-center operating mechanism includes a toggle mechanism having an upper toggle (74) and a lower toggle (122) coupled by a spring pin (128) to form a toggle joint about which the toggles can relatively pivot. The spring pin has a circular groove (128b) at which it operatively connects to the toggle joint, and a circular surface (128a) adjacent the groove is disposed in the path of travel of the contact arm as the contact arm swings to break the current path.

Abstract: A molded case circuit breaker has control terminals mounted on the front of the breaker and accessible from the front. A transparent plexiglass cover is positioned over the terminals to prevent inadvertent contact with the terminals and an opening is provided in the side of the casing for the egress of the control wires. With the control terminals on the front of the circuit breaker, an inspection can be performed without disconnecting power from the breaker.