MENNEKES MSR Series switched and interlocked receptacles combine UL 1686-C1 compliance with safety and flexibility. They provide an interlocking receptacle and HP-rated disconnect switch in one pre-wired NEMA 4X; 12 unit that’s easy to install. A patented interlock mechanism prohibits the switch from being turned "ON" unless the plug is fully inserted, and the plug cannot be removed unless the switch is turned "OFF."