US Patent 7623042 Wireless network control for building lighting system

Wireless control of lighting fixtures via a wireless radio network using a radio-controlled relay device located between a lighting fixture or a ballast of a fluorescent fixture and its power supply. The radio-controlled device receives signals from remote controllers or via a computer interface. The wireless device is also configured to monitor the power consumption of a lighting fixture (or ballast) and send that information to the network. In the wireless control network, light level sensors and motion sensors also send information to the network to allow lights to respond to daylight levels or occupancy.