Abstract: A conventional elevator system includes an elevator shaft, an elevator cab and means for moving the elevator cab along the shaft. The elevator cab has a sliding cab door to provide access thereto and electrically operated means for moving the cab door. A door buck opening into the shaft is provided with a shaft door movable relative to the buck to expose the cab door when the cab is aligned therewith. An interlock mechanism is provided connected between the shaft door and buck which, when actuated by the closing of the shaft door, completes an electrical circuit thereby permitting actuation of the means for moving the cab door to close same and, in turn, the means for moving the cab along the shaft. The present invention relates to a secondary interlock means located within the shaft wall above the door buck and operably connected to prevent completion of the electrical circuit of the primary interlock means by external means to bypass the primary interlock mechanism when the shaft door is opened.