System Sensors PSP1 plug-in switch is a special application supervisory switch designed for applications where no other type of listed valve supervisory switch can be installed. The PSP1 is to be used on non-rising stem gate valves and ball and angle valves. The unit is approved for Class A and Class B circuits. The PSP1 consists of a rugged rain tight metal housing. With its NEMA 3 rated housing and water-resistant cord, the PSP1 may be used in either indoor or outdoor applications. The PSP1 features a 360 versatile mounting design and an adjustable length cord which allow more freedom to install the unit at the most desirable alignment angle. The PSP1 employs a supervisory cord which, when pulled out, closes a set of normally open contacts. A lockout feature prevents reinsertion of the cord until the cover is removed, and the unit is reset. Removal of the cover or cutting of the cord results in an open circuit.