referring to fig1 and 6 circuit breaker 11 is identical to circuit breaker 10 and those features of circuit breaker 11 which are hereinafter mentioned and which are identical to those of circuit breaker 10 will be identified by the same reference numerals followed by 39 the rear sides 24 24 39 of circuit breakers 10 11 face toward each other and are gap separated by gap 35 behind each casing rear surface 24 24 39 is respective backing plate 37 37 39 which includes projecting supports that extend into and engage the circuit breaker casings for holding the circuit breakers securely in position at the top of backing plates 37 37 39 is the junction 39 which includes a screw threaded riveted or the like connection for holding the backing plates in the position illustrated in fig6 the below described interlock 50 is contoured to provide clearance for the securement junction 39 as discussed further below referring to fig1 and 2 extending between the handles 32 and 32 39 is the handle cap 36 which bridges across seats on and is attached to the handles 32 32 39 it is the handle cap 36 that is pressed upon and this in turn depresses both of the handles 32 32 39 for operating the circuit breakers 34 on 34 and 34 off 34 beneath cap 36 is attached the cruciform shaped trip rock bar 38 which is suspended from the interior.