Retaining device for mounting electrical units

Abstract

A retaining device releasably mounts and retains an electrical unit, such as a circuit breaker, within a panel opening. A face plate on the unit overlaps the panel to stop the unit at the panel opening. The retaining device has at least one resilient retaining arm projecting from the unit having a cam surface for engaging an edge of the opening to depress the retaining arm from an original position as the unit is inserted until a retaining surface of the arm passes the edge of the opening and allows the retaining arm to move back toward its original position to hold the panel against the face plate. The retaining device includes a separate lock arm projecting from the unit having a latch element and a latch release. Depression of the lock arm from an original position during insertion of the unit into the opening permits the latch element to clear the edge and pass through the opening. Thereafter, the return of the lock arm toward its original position permits the latch element to abut the panel to prevent withdrawal of the unit from the opening unless the latch release is actuated to depress the lock arm as the unit is withdrawn to permit the latch element to clear the edge and pass back through the opening as the retaining arm resiliently yields against the edge and passes back through the opening.