As if by magic, when you approach your house, lights ignite. Then,
once you've walked inside, living room sconces gradually brighten to a warm
glow and lights continue to turn on as you walk through the house.
Infrared or ultrasonic sensors turn lights off or on automatically, depending
upon whether or not they sense the presence of someone in the room. These
are made by several companies--Leviton, LightAlert!, and LVS to name a few.
Infrared types pick up minute changes in infrared background of a room that
occur when a human is present. Ultrasonic are activated by inaudible sound
waves that sense motion.
Wall-mount occupancy sensors replace a standard single-pole switch--they
don't require special wiring. Ceiling-mount models, which can cover a larger
room, are generally installed when a house is built because most have wires
that run from the sensor to a switch.
Other related products are available, too. LVS makes a fluorescent light
fixture with a built-in occupancy sensor that's ideal for closets or a laundry
room. Lamson Home Products makes a motion-sensing light adapter that can
be screwed into a conventional light socket--ideal for security lighting.
--Don Vandervort
