How to Convert Outdoor Light to Turn on Automatically at Night

Convert your outdoor lights to turn on at night automatically using a photocell.

I wanted to convert my exterior light in front of my garage to turn on automatically at dusk and off at daylight.

Bonus Tip: Save even more money on electricity by using a fluorescent or LED bulb instead of a regular incandescent bulb for this project.

A 100 watt incandescent bulb running for 12 hours will consume 1,200 watts. A 100 watt equivalent fluorescent bulb using only 23 watts running for 12 hours will consume only 276 watts. That's almost 1,000 watts less! This is a fun project to do and it's pretty satisfying when you see your upgraded light fixture spring into action every night by saving you money, illuminating your property and making it safer.

You can pickup the main component for this project at Home Depot, Radio Shack, or a hardware store. I purchased my Replacement Wire-in Photocell for Outdoor Lights at Home Depot, it cost me a whopping $7.00 and installation was extremely simple. I also bought a 100 watt equivalent fluorescent bulb, which only uses 23 watts of power at $6.73 a pop.

DISCLAIMER: This project requires that you deal with electrical work. If you do not feel safe doing this project, hire an electrician or handyman by using the form below.


  • Electrical Caps

  • Electrical Tape

  • Wire-in Photocell for Outdoor Lights (2 wire installation)

  • Basic tools to remove and reinstall your light fixture.

  • Glue Gun or Double Sided Tape

Getting Started On Your Automatic Exterior Light Project

Convert Light Fixture with Photocell to Turn On Automatically1. Turn off your circuit breaker to your outdoor light.

Safety TIP: Leave your outdoor light turned on and flip the breaker switch for it. Once the light has turned off, you know that you have found the correct breaker. For extra safety double check the light fixture by toggling the lights switch on and off a few times to ensure that the exterior light does not power on anymore.

If you have never worked with electricity before, go ahead and turn off all the breakers, that way there should be no power at all going through your entire house.

2. You will have to most likely disassemble the housing for your exterior light. Mine was mounted right above the garage door. Once I had the housing disassembled, I took a photo, and you should do so as well.This way, you know exactly how to put things back in case you make a mistake,

 Afterwards, I cleaned the fixture up and used some black spray paint to refurbish the fixture. After spraying two coats of black paint on the fixture, I let it air dry in the sun for 30 minutes.

3. The Photocell is really simple to install, it only has two black wires and it basically needs to be tapped into the black wire that is already running to your light fixture from your house.

4. Separate the connection between the existing black wire from your house and the light fixture.

5. Connect one photocell wire to the black wire coming from your house and twist the exposed copper wire together tightly.

6. Now connect the second black wire from the photocell to your light fixture, and also twist the exposed copper wires together.

6. Put electrical caps on both of your new connections and twist them several times or until the cap tightens around the wires noticeably.

7. Tape the caps to the wires with electrical tape.


8. Now we are going to test the photocell by turning on the circuit breaker to the outdoor light, and by covering the photocell eye with your hand. If the light turns on when you cover the cell, you know that you did a proper job. If it doesn't, try cupping your hand over the photocell. Sometimes the cells are too sensitive and the only way they turn on is if they sense total darkness all the way around. If that still doesn't work, turn off the circuit breaker again and remove the photocell. Now reconnect your wiring to how it was in the original state (Refer to the picture you took). Then turn on the breaker again and test to see if the light works. If it does, and it should, you may have a broken photocell.

9. Reassemble your light fixture and wait for nightfall to collect brownie points from your wife or husband !


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