Abstract: A circuit breaker includes separable contacts, an operating mechanism structured to open and close the separable contacts, a molded enclosure comprising a first molded portion and a second molded portion, a plurality of thread cutting screws fastening the first molded portion to the second molded portion, and a plurality of machine screws. The first molded portion and the second molded portion cooperate to form a plurality of exterior walls. The exterior walls define an interior volume, which encloses the separable contacts and at least a portion of the operating mechanism. The machine screws extend within and reinforce the exterior walls and restrict expansion of the exterior walls away from the interior volume.

Abstract: A circuit breaker includes fixed and movable contacts, an operating mechanism including a movable arm carrying the movable contact, an arc chute including a plurality of spaced apart first and second arc plates, and a slot motor. A slot motor structure is disposed about the contacts and a portion of the movable arm. An insulative housing at least substantially covers and insulates the slot motor structure from the movable arm and contacts. The insulative housing includes a base and a pair of arms disposed therefrom. Each of the arms includes a first portion disposed proximate the first arc plates and a second smaller portion disposed proximate the second arc plates. A space extending from the first portion, not occupied by the second portion, is generally occupied by a portion of the second arc plates. The second portion forms a debris shield between the second arc plates and the operating mechanism.

Abstract: An improved lockable fastener that can be employed in a circuit breaker application includes a first member and a second member that are threadably cooperable with one another and a locking member that extends between the first and second members to resist loosening of the first and second members. The second member includes a threaded shank that is threadably received in a first threaded portion of a cavity formed in the first member. The locking member includes a threaded body and a taper, with the threaded body being threadably receivable in a second threaded portion of the first member, and with the taper being at least partially receivable in a receptacle formed in the shank of the second member. The receptacle defines a seat on the shank, and the taper engages the seat to deform at least a portion of the shank into engagement with a ledge that is interposed between the first and second threaded portions of the cavity.

Abstract: The magnetic trip device of a circuit breaker has a magnetic pole in which a magnetic field is generated by load current, and an armature assembly that includes: a bracket supported for pivotal movement relative to the magnetic pole; a spring biasing the bracket to a position spaced from the magnetic pole; an armature hinged on the bracket; and an adjusting screw for adjusting a gap between the armature and the magnetic pole for calibrating the trip device without affecting the spring bias, which can be separately and independently adjusted to select the load current at which the magnetic trip is initiated.

Abstract: Rectangular bus bars alternatively engaged in either of a pair of crossed slots in a support block secured in a panel board are locked in place by a locking device incorporated in a cylindrical terminal portion of each bus bar. The locking device includes an expandable ring seated in a circumferential groove in the cylindrical terminal portion. A pair of actuating pins are urged radially outward in diametrically opposed bores to wedge the expandable ring against the support block, by a tapered screw threaded into a central longitudinal bore in the terminal portion of the bus bar.

Abstract: An auxiliary terminal block for an electrical switching device includes a molded block and at least one terminal for terminating the internal wiring and external wiring of the switching device. The molded block has a first wiring channel for the external wiring, a second wiring channel for the internal wiring, and a partial partition between the two wiring channels. The partition has a slot for engaging and locking the terminal after the internal wiring has been terminated. The partition may include two walls having a generally constant width therebetween. Shoulders or tabs may be disposed on each of the walls for engaging and locking the terminal to the block. Alternatively, the partition may include two walls which are at least partially resilient and which form a generally V-shaped opening between the two wiring channels. A shoulder may be disposed on each of the walls for engaging and locking the terminal to the block whenever the terminal is fully inserted within the partition.

Abstract: A locking device is insertable into a cover opening adjacent to a handle of an electrical switch to occupy the space in the cover opening for resisting movement of the handle. The locking device has two pivotally connected members. The pivotal movement of the members creates a collapsed condition or an expanded condition for the locking device. The pivotal members have a transverse opening which are alignable relative to each other when the locking device is in its expanded condition. The locking device is inserted into the cover opening when the pivotal members are collapsed. In a first embodiment, a handle shroud member has an opening for receiving the handle and a second member has leg means along its base for engaging an undersurface around the cover opening when the locking device is in its expanded condition. In a second and a third embodiment, both pivotal members have leg means for engaging undersurfaces around the cover opening when the locking device is in its expanded condition.

Abstract: A molded gasket for a line conductor in a circuit breaker acts as a gas seal to prevent ionizing gases resulting from a circuit interruption from flashing over and causing phase-to-phase and phase-to-ground faults. The molded gasket includes provisions for sealing the line conductor at the interfaces with the circuit breaker housing as well as providing a barrier for the movable contact arm assembly.

Abstract: A screw-nut arrangement for securing two or more members together is provided with a unique design for a locking nut insert. The locking nut insert has a straight knurled cylindrical portion with an end surface which abuts a shoulder in a counterbore of a through hole and a gripper retainer ring mounted adjacent to the knurled portion. The retainer ring is fabricated from strip material with grippers punched outwardly and is formed into an annular sleeve which fits around the locking nut insert. The retainer ring is held onto the locking nut by a collar.

Abstract: A molded case circuit breaker is provided with a two piece cradle assembly having a cradle portion and a heat-treated portion. The heat-treated portion forms the latch and reset surfaces. The cradle portion is integrally formed from a pair of spaced apart cradle-shaped arms joined together by a connecting portion. The heat treated portion is securely fastened to the connecting portion to form the two piece cradle assembly. A hold down slidably carries a handle barrier with respect to the cover and closes a centrally located aperture in the cover for all handle positions. The handle barrier prevents arc products resulting from a separation of the main contacts from escaping through the centrally located aperture in the cover. Stops are provided in one or both directions to prevent misalignment of the handle barrier with respect to the operating handle. A cover interlock is also provided to prevent the cover from being removed when the circuit breaker is in an "on" position.