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Multiple Motion Detectors for Light Fixtures

Can Two Motion Detectors be Used to Control Outdoor Flood Lights? How to Wire Multiple Motion Detectors for Outside Lighting.

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Motion Detectors for Outdoor Lights
Electrical Question: Can two motion detectors be used for outdoor flood lights?

This electrical wiring question came from: Ricky, a Homeowner from Fayette North Carolina.

Dave’s Reply:
Thanks for your electrical wiring question Ricky.

Multiple Motion Detectors for Outdoor Lighting

Application: Wiring Motion Detector Controlled Light Fixtures.
Skill Level: Beginner to Intermediate – Best performed by a Licensed Electrician.
Tools Required: Basic Hand Tools and Non Conductive Ladder.
Estimated Time: Depends on personal experience, the light fixture and access to the motion detector light fixture.
Precaution: Identify the light fixture circuit, turn it OFF and Tag it with a Note before working with the wiring.

How to Wire Multiple Motion Detectors for Outside Lights

I have tested this type of control system before, and what I found is that if you wire two motion sensors directly together they will conflict with each other and cause the light fixture to turn on and off rapidly. However, two or more motion detectors can be wired for this type of application using another method which is  explained below.

Wiring Two or More Motion Detectors and Light Fixtures

See the application where this system was installed at a project for Lighting Covered Stairs

Additional Options for Controlling Outdoor Light Fixtures

Typical Wiring Diagram for this Application

wiring diagram motion detector controls

More about Wiring Motion Detector Light Fixtures

Wire Motion Detector Lights
Installing Motion Detector Light Fixtures
Installing motion detector lighting fixtures provide security and energy savings and they can easily replace an existing exterior wall fixture.


More about Electrical Relay Construction and Purpose – Part 1

Electrical Wire for Motion Detectors

Electrical Wire for Light Fixtures
Complete listing of electrical wire types and parts used for home projects with electrical code information serves as selection guidelines.

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FAQs Frequently Asked Questions and Comments

6 Responses to “Multiple Motion Detectors for Light Fixtures”
  1. Howie says:

    Can you explain what a relay is? If its a product, how do I choose the correct relay for the application. Finally, how to wire a relay to connect multiple motion detectors to a string of lights? I have checked multiple sources and everyone gives the same answer in using multiple motion detectors for a string of lights, use a relay, but nobody explains how to do it.

  2. Dave Rongey says:

    Howard, I have added a link to the relay section of the website. There are a few wiring diagrams and some information that should help you. If this does not help then make another comment and I may have to get a little more practical information for you. Dave

  3. Tom Fettig says:

    Did you mean this to read:
    I would like to control my outdoor flood lights with more than one motion detector so the light can be triggered to come on if there is movement detected in different directions.
    If this can be done using standard motion detectors,

    (do both red wires from the motion sensor tie to each other.)
    Change to:
    (Tie both red wires from the motion sensor tie to each other.)

    Then the two black wires from the motion sensor will tie to the hot wire from the main power.

  4. Dave Rongey says:

    Hi Tom,
    With this type of setup the motion detectors do not tie to one another. Each motion detector must connect to a separate control relay. I have tried connecting the red wires from the motion detectors to each other and for some reason when motion is detected the two motion detectors make the lights flash on and off. However when I wired each motion detector to a separate relay the lights would control properly. This method can be used when there are motion detectors that are far apart, or at separate levels. This way if any of the motion detectors still detects motion the connected relay is still activated, therefore the lights will still stay on, even though another motion detector may not be detecting motion. This way the passageway remains lighted until there is no motion detected and the set time delay has expired.
    Thanks for your input Tom. I realize this will create questions and that is OK. I will be producing a wiring diagram to explain the wiring in detail.
    I also placed a link to the page where this setup was installed, and I will add more information showing the final working system.
    I hope this helps,

  5. chris says:

    I have a Boulder outdoor motion detector. I think the model number is NW-12 300 watts output. It has four wires coming from the inside of it, two white, one black, one red. I have a light fixture with two light bulbs each one of them has a white and a black wire coming out of them how do I hook this up?

  6. Dave Rongey says:

    Hi Chris, Typically the black wire on the motion detector is connected to the black wire of the incoming circuit power of the light fixture box. The red wire of the motion detector connects to the black wires of the lights. The white wires of the motion detector, and the lights all splice together with the white wire of the incoming circuit power cable. Be sure to consult the wiring diagram and documentation that came with the motion detector for specific instructions.
    I hope this helps you,