Motion sensors automatically control outdoor lights. Depending on the model and sensitivity of the motion sensor, even a small animal will activate the light switch. Installing a motion sensor to an existing fixture will take approximately an hour of time, if you have the proper parts and a few hand tools.
Remove all electrical power from the outdoor light fixture that is going to be wired for the motion sensor. This may entail shutting off the circuit breaker or pulling the fuse that supplies power to the electrical circuit.
Unscrew and remove the light bulb from the fixture. Dismantle any glass lenses or covers from the light fixture.
Pull the fixture from the electrical box. Use the pliers to loosen any fixture nuts or the screwdriver to loosen any mounting screws. Observe the electrical connections inside the light fixture mounting box.
Loosen and remove the plastic wire nuts from the wire connections. Note the black insulated wire is the power supply, and the white insulated wire is the electrical system neutral wire. The bare copper wire that is connected to the light fixture itself is the electrical systems grounding wire.
Observe the electrical wires on the motion sensor. Typically, three wires are attached to a motion sensor. Refer to your particular model for any specific instructions or connections as various models may have different wiring methods. The most common motion sensor will use a red insulated wire, a black insulated wire and a white insulated wire.
Use the wire strippers and remove ¾ of an inch of the insulation from the motion sensor wires to reveal the bare copper underneath.
Mount the motion sensor to the outdoor fixture. Typically there are two ½-inch diameter "knock out" holes on the exterior fixture. Use the screwdriver to remove one of the ½-inch diameter metal discs to make the hole. Fit the threaded portion of the motion sensor through the ½-inch diameter hole. Place the electrical nut over the threads to tighten the motion sensor to the exterior light fixture housing. Finish tightening the electrical nut with the pliers.
Connect the electrical wires in the following order. Twist the red insulated bare copper wire from the motion sensor together with the black wire from the light fixture. Make a good electrical connection using the pliers. Cover with a plastic wire nut. Twist the two white wires together in the same fashion. Cover the bare copper wires with a wire nut. Connect the black wire from the motion sensor to the black wire that is coming from the power supply circuit breaker or fuse. Finally, connect the bare grounding copper wire back to the metal housing on the light fixture.
Install the fixture onto the electrical box. Replace any glass lenses and the light bulb. Reenergize the electrical circuit by turning on the circuit breaker or installing the fuse. Turn on any interior light switch that controls the fixture. Move your hand in front of the motion sensor. The light should come on. Consult the manufacturers directions for any specific instructions concerning angular and sensitivity adjustment to the motion sensor.