Introduction: Turn Your Outdoor Lights Into Motion Detector Lights

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Having exterior lights is a great idea to increase the security of your home at night. But, there are definite downsides to leaving lights on all night:

  1. Burning the midnight oil! Electricity costs can be high for high-wattage incandescent lights. Even halogen floods can be costly when run for 8-10 hours EVERY night!
  2. Bugs and spiders, oh my! Nobody likes walking through spider webs or having insect remains and spider pool all over the side of your house. If you light it, they will come.

That's where a motion detection kit can transform your existing lights. As an added bonus, a light that turns on only when it senses a person or animal is more likely to scare away a threat and get your attention.

Check out a more detailed write-up at

Step 1: Make Sure Your Current Light Box Has Knockouts for New Wiring

Step 2: Gather the Stuff You'll Need

Here's the list of things you'll to buy:

  1. Motion sensor - Make sure you get one that has a threaded interface that matches the knockout on your light box (most likely 1/2" or 3/4" knockouts). I picked up this Cooper unit at Amazon for $15 (
  2. Wire nuts - Your wires are most likely 12 or 14 guage, make sure you get wire nuts that will accept at least 3 12 ga. wires. You probably have some already, but here's a link if you don't (

And here are the tools you'll need to make it happen:

  1. Philips screwdriver
  2. Wire strippers (you can get by with a sharp knife too)

Easy enough, right?

Step 3: Turn Off Power to the Light

Turning off the light's circuit at the breaker box is the best way to make sure it won't be inadvertently turned back on. Make sure others in the house know you're working on the light (and won't turn power back on) and verify the light goes out when you flip the breaker to make sure you turned off the correct circuit.

It's always best to verify no power is present in the box with a probe or meter before starting work!

Step 4: Remove the Cover Off of the Existing Light and Prepare the Light

All you need to do is disconnect the hot wire from the light. Instead of being powered from the breaker, the light will now get it's power from the motion sensor. It essentially acts as a switch for your light after it's installed.

Step 5: Remove the Knockout for the Motion Detector and Run the New Wires Into the Light Box

Step 6: Follow the Instructions for the Motion Detector to Wire It to Power and the Light

Usually, you will connect white and black wires from the house to those on the motion detector and connect the red wire (switched voltage) to the black wire on the light. The common wire (white) on the light will still be connected to the white from the house and the common from the motion detector.

BUT, make sure you follow the instructions with your motion detector and ask for help if you get stumped. Taking some extra time is better than getting hurt or shorting something out.

Also, make sure there are no exposed wires before you tuck them back into the electrical box.

Step 7: Reinstall the Light Onto the Electrical Box and Test It Out!

Depending on the motion detector you bought, you may need to set switches to change it's behavior to not turn on during the day or stay on all night. Regardless, most will let you enter a test mode during the day to see if the detector is working correctly.

After place it in test mode, simply wave your hand in front of the light to make sure it comes on.