The paper concludes:
In response to a growing need to save energy and provide optimal lighting control, designers are turning to UL 924-listed [Automatic Load Control Relays, or ALCRs] to control emergency lighting circuits. ALCRs are intended to ensure that required emergency lighting comes on when needed, while being controlled at other times, usually in tandem with normal devices such as relays or occupancy sensors. The ALCR (and its load) is fed from one of the building’s emergency power branch circuits and will always have power available to it. It is not a transfer switch and does not switch between normal and emergency power. Rather, it senses the normal power line and energizes its load whenever needed, providing monitoring at the branch circuit level to ensure proper operation during local or building-wide power failures.
Download the whitepaper at http://www.wattstopper.com/getdoc/1967/ELCUWhitepaper.pdf.