Circuit breaker housing and attachment box

A circuit breaker assembly comprising;

• an outer box enclosing an attachment having an operating element for the circuit breaker and having an open bottom, a closed top, a front wall and a pair of side walls, each side wall including a linear projection extending vertically and the front wall having a central recess, outlet openings for lead wires in said recess, and first and second engaging means, each including an engaging hole and each projecting downwardly at opposite ends of the front wall;
• and
• a circuit breaker housing comprising a cover portion and a case portion having an interior, the cover portion including a recess having an open top, a pair of side walls each provided with a linear channel, and a bottom wall which includes an opening, said outer box adapted to fit in the recess of the cover portion, the linear projections of the outer box fitting slidably in the channels of the side walls of the cover portion, the operating element of the attachment in the outer box adapted to extend through the opening in the bottom wall of the cover portion to the interior of the case portion, the front wall of the circuit breaking housing including a pair of channels each of which includes an interlocking projection, the pair of engaging means of the outer box adapted to fit into said pair of channels with the engaging holes accepting the interlocking projections.