Why is my photocell light flashing

How to Fix a Dusk to Dawn Light Fixture

How to Repair a Dusk to Dawn or Motion Detector Light Fixture: Security Light Fixture TEST Setting Functions, Replacing a Motion Detector Head on a Dusk to Dawn Fixture, How to Test a Photo Cell.

What To Do If Your Dusk To Dawn Fixture is Erratic
Electrical Question #1:My dusk to dawn light has become erratic, coming on at dusk, staying on a while, going out, coming back on for a few minutes, going out, coming on for a while, going out.

  • The security light fixture has worked perfectly for several years.
  • Should I change the light bulb, sensor or the whole light?


This electrical wiring question came from: Rick who is a Handyman from California.
See more about Electrical Wiring in California

Electrical Question #2:

  • My next door single lady has two great hard to reach motion detector lights facing our shared driveways.
  • They have worked well for some time, but have decided either to be on or off.
  • She said she accidentally turned the inside single switch which operates them and now can not get them to turn on only at night when motion is detected.
  • She says she had the instructions how to activate them properly from the single interior switch, but can not find them.Thanks for your help, Dave!

This electrical wiring question came from Chuck, a Handyman in St. Louis, Missouri.

Dave’s Reply:
Thank you for your electrical questions.

How to Repair a Dusk to Dawn or Motion Detector Light Fixture

Application: Repair a Dusk to Dawn Light Fixture.
Skill Level: Beginner to Intermediate. This electrical project is best performed by a Licensed Electrician or Electrical Contractor.
Tools Required: Basic Hand Tools and Safe Ladder.
Estimated Time: Depends on personal experience, the light fixture and access to the light fixture.
Precaution: Identify the light fixture circuit, turn it OFF and Tag it with a Note before working with the wiring.
Notice: Replacement parts for the security light fixture should be compatible with the type of fixture that has been installed.

Security Light Fixture TEST Setting Functions

  • Be sure that the motion detector head is not switched into the TEST setting.
  • The TEST setting will over-ride the photo cell and will cause the fixture to trigger the lights to come on when any movement is sensed at any time.

Replacing a Motion Detector Head on a Dusk to Dawn Fixture

  • If necessary the motion detector head may be purchased to replace the defective motion detector head.
  • You will notice that there are a variety of sensing capabilities available, and the more sensitive the head the higher the price.
  • You may also want to compare the price of the motion detector head all by itself compared to a whole new light fixture.
  • Replacing the motion detector head typically involves the following three wires:
    • Black wire for the incoming power.
    • Red wire for the outgoing power to the light bulb sockets.
    • White neutral wire, which is typically spliced together with the white wires of the incoming power source neutral, and the white wires to each light socket.

How to Test a Photo Cell

  • If the outdoor light fixture does not have a standard motion detector head with a TEST switch option, and you need to test the photo cell, then follow the example in the following process:
    • Locate the photo cell on the light fixture, or the external photo cell control.
    • Typically the actual photo cell is inside the unit behind a round clear plastic lens, which may be located on the bottom of the motion detector, or the front side.
    • With the power on to the light fixture, place a small strip of black electrical tape over the photo cell to block the light.
    • Depending on the photo cell it may take about 30 seconds for the photo cell to turn on.
    • If the photo cell and control circuitry is functioning properly, and the light bulbs are good the fixture should light up.
    • After testing the photo cell be sure to remove the black electrical tape which will place it back into the automatic mode of operation.

How to Reset a Motion Detector Light

  • Most motion detectors are activated into the Off, On or Auto mode using the power source, which in this case is the wall switch. To do this turn the switch Off, then wait about 6 seconds, and then turn it back On. Each time this is done the motion detector will toggle into the next mode of operation.
  • NOTE: Some motion detectors come with small switches on the bottom that will activate these settings as well.

Part Reference: Dusk to Dawn Light

More about Wiring Motion Detectors and Dusk to Dawn Light Fixtures

Dusk to Dawn Lighting and Motion Detector Wiring

  • Installing Motion Detector and Security Light Fixtures

  • Installing motion detector lighting fixtures provide security and energy savings and they can easily replace an existing exterior wall fixture.

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