How to Wire Interior Motion Sensors

Updated February 21, 2017

Wiring motion sensors to interior lights is a great way to save energy while adding a little convenience to your home. Interior motion sensors are perfect solutions for controlling the lights in a room where not a lot of time is spent, like a garage or a basement. Simply walking into the room is enough to turn the lights on, and once out of the room, the lights will automatically go out according to the timer on the sensor.

Determine where in the room the motion sensor should be installed. Cut away the drywall to fit the old-work ceiling box. For the easiest installation, the motion sensor should be located near the first light fixture in the circuit so you can control all of the lights on the circuit through a single branch connection.

Turn off the power to the lighting circuit by finding the correct circuit breaker and toggling it off.

Open up the light switch so you can test the wires for voltage using the touch-type voltage tester.

Locate the line that is travelling from the wall switch to the first fixture in the series. This cable will have to be cut so it can enter and leave the ceiling box for the motion sensor.

Insert both ends of the feed line into the ceiling box and install the box inside the ceiling. Secure it in place by tightening down the four screws.

Strip away the outside sheath from the two cables to reveal the individual wires. Use the wire strippers to remove about 3/4 of an inch of insulation from the end of each insulated wire. Pay attention so you know which wires are coming from the switch, and which wires are travelling to the fixture.

Connect the ground wires together using a wire connector. Stuff them back inside the ceiling box.

Connect the two white wires in the ceiling to the white wire on the motion sensor. Secure them with a wire connector, and wrap the connection with electrical tape.

Connect the black wire in the ceiling coming from the switch to the black wire on the motion sensor using a wire connector. Wrap the connection with electrical tape.

Connect the black ceiling wire going to the light fixture to the red wire on the motion sensor using a wire connector, and wrap this connection with electrical tape as well.

Secure the interior motion sensor to the ceiling box, and turn the circuit breaker back on.

Leave the wall switch in the on position, and test out your installation. As long as there's movement in the room, the lights will stay on. Once you leave the room, the lights should go out in a few minutes.


Never cut an electrical cable unless you know for sure that the power is off. Always test the wires before making a cut to avoid injury.

Things You'll Need

  • Motion sensor(s)
  • Screwdrivers
  • Wire strippers
  • Touch-type voltage tester
  • Electrical tape
  • Old-work ceiling junction box
  • Drywall saw
  • Wire connectors
Cite this Article A tool to create a citation to reference this article Cite this Article

About the Author

Based in Atco, NJ, Dave Donovan has been a full-time writer for over five years. His articles are featured on hundreds of websites, and have landed him in two nationally published books "If I Had a Hammer: More Than 100 Easy Fixes and Weekend Projects" by Andrea Ridout and "How to Cheat at Home Repair" by Jeff Brendenberg.