Outdoor motion lights can save you money because they turn lights on only when you need them. Having an automated light outside your door makes coming home after dark much safer and more pleasant. They're convenient because you don't have to fumble around looking for a switch, and they add to a home's security.
Turn off the circuit breaker that supplies power to the fixture.
Unscrew the light bulbs in your existing fixture and test the fixture to make sure there's no voltage running through the wires. Place one prong of your voltage tester on the brass threads inside the empty light socket. Place the other prong on the center metal tab at the bottom of the empty light socket. Read the voltage meter on the display of the voltage tester to make sure there's no power.
Remove the screws that connect the existing fixture to the wall, and pull the fixture away to expose the wiring.
Untwist the wire nuts that secure the wires together, and slowly pull the wires apart. If there is any electrical tape around the wires, remove that as well. To ensure optimum safety, don't touch the bare wires as you work. Pull the fixture away from the wall completely once you disconnect all of the wiring.
Place a mounting strap over the existing electrical box and screw it in place.
Hang the watertight gasket, which should come in the package with your new outside motion light, over the electrical wiring that sticks out of the electrical box. This helps protect wiring from the elements.
Run the bare copper wire, located inside the electrical box, to the green screw inside the motion light fixture. This acts as the ground wire. Rotate the copper wire clockwise, forming a loop, then tighten it around the green screw. Tighten the screw to secure the copper wire in place.
Connect your electrical wiring according to the color-coded system. Pair the white neutral wires together, and screw a wire nut over the top of the pair. Twist them together and make a solid connection. Do the same for the black wires, which are the hot wires. To secure the wire nuts in place, wrap electrical tape around the bottom of each wire nut.
Secure the base of motion light to the wall. Line up the base with the watertight gasket and screw the light into the mounting strip, using the screws provided. Restore power to the light.
Read the owner's manual for instructions on how to set the motion sensor sensitivity and the delay time. Usually on the base of the fixture you'll find a tab that you can adjust to set the amount of time you want the light to stay on after it detects motion and the distance you want the motion sensor to respond to. Contact an electrician to run the appropriate wires if you want to conduct motion light installation in an area where you do not have an existing light fixture.