Installing a Motion Detector Light

Get tips on how to safely install a motion detector into an existing outdoor light. Making sure the power is off before you work with wires can keep you safe.

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LESLIE: Coming up, we have a call from Mike in Indiana who wants to know about installing some lighting himself.

Mike, what kind of lighting are you looking to do?

MIKE: Well, what I’m interested in is a motion detector light that comes on during the night if someone or something is prowling around your backyard. And I was wondering if it’s possible for a fellow that doesn’t have much electrical experience to install one of those motion detector lights himself.

TOM: Do you have a light fixture right there, Mike? Is it just a spotlight now and you want to put a motion detector on it?

MIKE: It’s just a backdoor light right now.

TOM: OK. Well, let me say this cautiously. It’s not a very hard thing to do as long as you can be absolutely sure the power is off. There’s usually just a couple of screws that hold the light fixture on and then, typically, there’s three wires – a black one, a white one, and a ground – and you simply replace them wire for wire and then put the thing back together. And in the instructions for the motion detector, it’ll show you how to adjust it. Usually there’s a test cycle where you set it and a test button and you can actually test to make sure you know where it’s going to come on and when it’s going to come on and so on.

So it’s not that hard to do as long as you’re absolutely sure that the power is off. If you have any level of discomfort though in making sure that your power is off, then I would recommend that you contact an electrician. But if you told me you were wiring the circuit and you had to hook it up to the panel and all this sort of thing, I’d say no way, no how, don’t do it. As long as it’s just wire for wire and that you know that the power is off.

MIKE: It’s clearly marked on the box which switches to throw.

TOM: Don’t always believe the labeling. Make sure the light’s on, the light’s off.

LESLIE: Can’t you get some sort of device that tests the circuit to make sure that there’s no power coming to it?

TOM: Yes, you can. It’s a voltage detector and that’s not a bad idea. You can buy one for just a few dollars at the local home center store. I use one called a tick tracer. There are different manufacturers that make them and it basically detects a magnetic field around the wire. And so, with the power off, you sort of put the little tracer right in there and it’ll tell you if it’s off or not; just make sure. So if you’re absolutely certain the power is off, it’s not an issue.

LESLIE: And make sure you keep a friend around just in case it is.

TOM: (chuckles) There you go.

MIKE: Thank you very much.

TOM: You’re welcome, Mike. Thanks so much for calling us at 1-888-MONEY-PIT.