How to Wire a Motion Detector

By Dave Donovan

Motion detectors are a great addition to any outdoor lighting scheme. They offer improved security measures, and they help to keep your electric bill down by reducing the amount of time a particular light is left on.

Things You'll Need

  • Motion detector
  • Screwdrivers
  • Wire strippers
  • Wire connectors
  • Electrical tape
  • Voltage tester (touch type)

Step 1

The first step to wiring a motion detector is to choose which light you want to have the capabilities. It can be an entryway light, a light on the garage or pretty much any other exterior light on your home. You want to make sure that, where you are installing it, the detector will have a clear line of sight to the area you want it to scan. If there are bushes or tree branches in the way, then the motion detector will be sensing movement all night long and the light will never go out!

Step 2

Once you have the light chosen, turn off the circuit that powers the light. You can turn the switch off if you want, but for safety reasons, it's best to turn off the breaker.Next, remove the light fixture from the wall. Before you disconnect the wires, use the touch-type voltage tester to ensure that the line is turned off. After you check the voltage, disconnect the wires.

Step 3

Many exterior lights come with pre-drilled holes suitable for installing a motion detector or photo sensor. These access holes usually have a cap that can be unscrewed. Look on your light fixture for a knockout or access hole cap and remove it. If your light fixture does not have an access hole, you can create your own by drilling one in with a 3/4" hole saw or simply purchase a newer light fixture.

Step 4

Take your motion detector and make sure that it has the rubber weatherproof grommet inserted over its threads. Then, insert the wires through the access hole on the light fixture. Use the accompanying lock nut to secure the motion detector to the light fixture.

Step 5

Next, use your wire strippers to strip away any necessary insulation from the wires. You should have about 3/4" of exposed wire at the ends of each wire. Take the white wire from the motion detector and connect it to the white wire from the light fixture and the white wire coming out of the wall.Take the red wire from the motion detector and connect it to the black wire coming from the light fixture.Take the black wire coming from the motion detector and connect it to the black wire coming out of the wall.Make sure all of the wire connectors are on tight and wrap electrical tape around each one.

Step 6

Secure the light fixture back to the wall box and turn the circuit breaker back on. Now, when it gets dark outside, and something or someone walks in front of the motion detector, the lights will automatically come on!

Tips & Warnings

  • Most motion detectors have settings that you can personalize, like range of detection and length of time the light will stay on.