Abstract: A molded case circuit breaker includes a movable upper electrical contact having a base portion formed at one longitudinal end thereof with an elongated stop pin fixedly secured thereto and outwardly projecting therefrom for engaging one or more elongated upper spring arms of one or more torsion springs. A lower spring arm of each torsion spring is disposed in contact with a cross bar of an operating mechanism of the circuit breaker. During normal operation, the stop pin loads the upper spring arm with a force at a distance relatively close to the fulcrum of each torsion spring to cause the movement of the upper electrical contact in unison with the cross bar.

Abstract: A multi-phase circuit breaker characterized by a plurality of phase compartments separated by spaced barriers, a circuit breaker structure within compartment and having separable contacts, manually operable handle within one compartment and including a crossbar extending laterally through the compartments and barriers and each barrier having a removable portion that is retained in place by an overlying portion of a handle.

Abstract: A molded case circuit breaker includes an operating mechanism position indicator having a plurality of electrically insulating cards or strips disposed beneath an opening in the breaker cover about a manually engageable handle of the circuit breaker for movement in response to movements of the handle along the cover opening. A first one of the cards includes a pair of spaced apart, laterally aligned red markings for providing an externally visually discernible indication that the operating mechanism of the circuit breaker is in its CLOSED position. The first card also includes a pair of spaced apart, laterally aligned white markings for providing an externally visually discernible indication that the operating mechanism of the circuit breaker is in its TRIPPED position. The second card is positioned beneath the first card and is of a substantially greater length than the first card.

Abstract: A molded case circuit breaker includes a movable lower electrical contact having a formed stationary member, a movable contact arm, a pair of electrical contact compression springs, a contact arm compression spring and a contact secured to the upper end of the movable contact arm for physically and electrically contacting a separable upper electrical contact. An integral longitudinal end portion of the stationary member extends through the base of the cirucit breaker to form an external terminal of the circuit breaker. The opposite longitudinal end of the stationary member is curved for receiving a rotatable pin fixedly secured to the movable contact arm for rotation therewith. The rotatable pin is biased by the pair of compression springs into effective current conducting contact with the curved end of the stationary member. The contact arm compression spring contacts the underside of the movable contact arm to bias the contact secured thereto into engagement with the upper electrical contact.

Abstract: A molded case circuit breaker includes first and second pairs of separable electrical connectors disposed in adjacent poles of the circuit breaker and spaced apart by a spacing less than the spacing between externally extending electrical terminals for making external electrical connections to the same adjacent poles of the circuit breaker. The closer spacing is achieved by a plurality of integrally formed, molded projections formed in the base of the molded case of the circuit breaker for positioning movable portions of the lower electrical contacts spaced apart in the base by the above closer spacing.

Abstract: A molded case circuit breaker includes a movable upper electrical contact having a base portion with a slot formed therein for releasably receiving a portion of an elongated spring biased locking pin disposed in a rotatable cross bar of an operating mechanism of the circuit breaker. The locking pin is biased in the slot by a pair of tension springs secured to the cross bar, enabling the upper electrical contact to move in unison with the cross bar. Upon the occurrence of a high level short circuit or fault current of sufficient magnitude, the pin is displaced from the slot enabling the independent rotational movement of the upper contact arm. During such movement, an elongated leaf spring is downwardly deflected and then released by the base portion. Subsequently, the upper electrical contact is prevented from contacting the lower electrical contact by the engagement of the leaf spring with the base portion.

Abstract: A molded case circuit breaker includes a highly integrated operating mechanism having an over-center toggle mechanism for opening and closing a pair of electrical contacts and a trip mechanism for responding to overload and short circuit or fault current conditions to separate the pair of electrical contacts. A generally flat, intermediate latch plate includes an upper latch surface for latching with a movable cradle of the over-center toggle mechanism and a lower latch surface for latching with a trip bar of the trip mechanism and a pair of outwardly projecting pivot arms disposed between the upper and lower latch surfaces. The over-center toggle mechanism includes a pair of upper toggle links and a pair of lower toggle links interconnected by a toggle spring pin.