The TR Series Retrofit Lighting Relays are magnetically latching type devices with a built-in transformer for low voltage control of lighting circuits. Designed to mount in existing junction or pull boxes, these units can be connected to provide master sweep-off and sweep-on control of lighting while existing line voltage switches and wiring remain in place for local on/off and override functions. Low voltage inputs require momentary contact closures (SPDT for on/off control, SPST for off control only) and may be combined up to 40 per phase within Class 2 wiring limits. Relay contacts are 20A normally open and can switch up to a 1 hp motor load. This unique technology, which allows a single coil to serve as both a transformer secondary and a relay operator, results in a compact and economical package for both retrofit and new installations.