Electric switchboard apparatus with a breaker-fuse interlock

Claim 1

A circuit breaker-fuse interlock arrangement for an electric switchboard comprising: a first compartment in an electric switchboard containing an electric circuit breaker; a second compartment in said switchboard containing an electric fuse; means interconnecting with said first and second compartment for preventing said electric fuse from being electrically disconnected while said circuit breaker is electrically connected; first racking means for electrically connecting line and load plugs on said circuit breaker with first line and load stabs connecting with a power source and first blocking means in said first compartment for preventing access to said racking means; and second racking means for electrically connecting line and load plugs on said electric fuse with second line and load stabs connecting with said circuit breaker; said interconnecting means comprising a bell crank connected between said first and said second compartments wherein contact with said bell crank within said first compartment produces motion by said bell crank within said second compartment, a lift bar attached to said bell crank within said second compartment for becoming raised and lowered upon contact with said bell crank within said first compartment, a slide element intermediate said fuse and said lift bar for moving to a first position when said lift bar is raised and for moving to a second position when said lift bar is lowered, said slide element containing a pin projecting from a bottom of said slide and a tab projecting from said slide, said tab contacting said blocking means when said lift bar is in said first position.