Defeater for mechanical safety interlock for covers of explosion-proof electrical housing

Claim 1

In an explosion-proof electrical enclosure apparatus comprising a housing having a body with an access opening and threads therearound and a cap threaded onto said threads and covering said opening, an electrical switch within said housing and operable between a switch-open position and a switch-closed position, said switch having a member within said housing for moving the switch between said positions which member is operable from outside said housing, a locking device interengaging said cap and said body and movable between a first position at which said cap is locked at a desired location against rotation and a second position at which said cap is free to be rotated to unthread the cap for removal to expose said opening, and interlocking means operatively interconnecting the switch operating member and said cap locking device and including a locking part movable along a path between two positions respectively corresponding to said two positions of said member for retaining said locking device in said first position thereof so long as the member is in the switch-closed position while freeing the locking device for movement to the second position so long as the member is in the switch-open position, the improvement comprising: defeater means operatively engaging said interlocking means for moving said locking part along a second path between its position at the switch-closed position and a third position thereof at which it frees the locking device for movement to the second position, said defeater means includes an operating component unmanifestly located at the exterior of said body for moving said locking part along said second path.