The LiftMaster 50400 Switch, Pass Door is an OEM interlock switch engineered for commercial and industrial overhead door systems that incorporate a pedestrian “pass” or wicket door within the curtain or panel. Its core function is to disable powered door operation whenever the pass door is open, helping prevent accidental movement of the main door and supporting compliance with common safety practices and UL 325–related jobsite requirements. The switch provides a simple, dry-contact interlock in the operator’s low-voltage control circuit, so the door operator remains inoperative until the pass door is securely closed.
Intended for use with LiftMaster commercial door operators that provide a dedicated pass-door interlock input (such as many Logic series operators), the 50400 serves as a reliable replacement part for service, repair, or new installations on rolling steel and sectional doors equipped with an integrated pedestrian door. Typical installation mounts the switch so it changes state when the pass door opens, with wiring routed in series to the operator’s interlock/safety circuit; no external power is required. For proper function and to ensure code-compliant operation, installation and adjustment should be performed by a qualified technician following the operator’s wiring diagram and verifying that the main door cannot run when the pass door is open.