The 3Q Interlock is an electromechanical door interlock for the residential elevator market. It was designed to facilitate compliance with the 3/4″ hoistway door to landing sill space requirement. The clearance between the back side of hoistway doors and the hoistway edge of the landing sill shall not exceed 3/4 inches. This requirement is found in the ASME A17.1 national safety code for elevators, section 5.3.1.7.2. The 3Q Interlock measures less than 3/4″ in depth (0.6″), allowing it to fit behind the door and within the gap allowed by the ASME A17.1 code.