Hubbell Circuit-Lock pin and sleeve mechanical interlocks area revolutionary design that incorporates a disconnect switch and pin and sleeve receptacle in a compact non-metallic unit. These devices offer maximum safety by preventing users from mating or breaking a circuit under load-Hubbell™s interlock mechanism detects the presence of a plug and prevents it from being removed when the switch is in the "ON" position. It features a high visibility red handle that can be locked to meet OSHA lockout tagout regulations and the enclosure door can be locked to prevent unauthorized access. The rugged, corrosion resistant type 4X Valox enclosure features adjustable mounting feet for flexible installation, While the receptacle™s spring-loaded cover with gasket is dust tight and provides a watertight seal when turned and locked. The Patented Plug-Check mechanism detects the presence of the plug. It operates as a clutch to engage the handle with the switch and captures the plug. This action prevents the plug from being removed until the switch is turned off.