Whether you need a motion detector light in a laundry room so you don't have to fumble with a switch, or outdoors to light the way when you take out the trash or to alert you when someone walks up to your house, a motion detector light is a smart investment. Many people, however, don't want to replace a light fixture that works just fine with a new motion sensor light. Instead of getting rid of your existing fixture, upgrade it to a motion detector by adding a motion light sensor. This changes your existing light to a motion detector light and doesn't require you to mess with any electrical wiring.
Unscrew the light bulb out of your existing light fixture. Set the bulb to the side because you will use it again.
Place the threaded end of a motion light sensor into the socket. A motion light sensor screws into your existing light fixture to turn your existing fixture into a motion detector light.
Screw your light bulb into the motion light sensor by threading the bulb into the socket. Your light bulb screws into the motion light sensor the exact same way it screws into your light fixture. A motion light sensor works with light bulbs that are up to 100 watts.
Turn the light switch for that electrical fixture "On" and leave it in the "On" position. The light will turn on as soon as it detects movement, and it will remain on for four minutes after it stops detecting movement.
Install a motion light sensor in each light bulb socket if you have a fixture that uses multiple light bulbs.