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I am replacing a garage door opener that is hardwired. I have disconnected everything and inside I have three wires black, white, and red. My original plan was to wire up an outlet. In the past when I have wired an outlet

I have always had a ground wire. I did some research and it appears that you do not need a ground wire if you are in metal conduit. Is that correct?

Edit for picture The black, red, and white wires.

I was able to use an electrical ground tester on the box I put in and everything worked.

I am now doing the second garage door and it also has a red wire. The red wire on the first opener was screwed into a connector in the opener. In the second opener it was just screwed into the inside of the box, not connected to anything.

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  • Can you provide a few pictures of what you've got there? There seems to be some confusion.
    – JACK
    Nov 12, 2021 at 18:37
  • @jack Added an image Nov 14, 2021 at 18:44
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    Now with picture: That is not a metal conduit and that is not a ground wire. That is an armored cable, and the thin bare wire is a bonding wire that MIGHT allow you to use the armor as grounding, if it is permitted by code and if it is installed properly at both ends. I do not think it is possible to do that properly by mounting it directly to the motor housing because the cable inlet is designed for a plastic cord. The red wire was either unused or might be so a garage ceiling light can be switched on and off by the door opener.
    – jay613
    Nov 14, 2021 at 18:59

3 Answers 3

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Edit: This was an early answer assuming there was actually metal conduit in the wall with a metal box. Resulting comments and question edit showed that this was not the case...


Metal conduit can act as a grounding conductor if it was installed properly. You need to test to see if it provides a path to ground, and an easy way would be to see if there is continuity between the white wire (neutral) and the metal box and conduit.

If the conduit is acting like a ground any fixture or appliance that you install needs to be grounded with a ground screw in the back of the box. If you are installing an outlet, it also needs to be grounded. They do make outlets that are "self grounding" with metal spring clips that touch the metal box so you have to make sure you get the right outlet (not the cheap $1 ones...).

self grounding clip

Self grounding clip is the brass piece under the screw

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  • If I get one of these self grounding outlets will that solve my problem? Also I have the blue old work box as the receptacle. Would you recommend the metal one? Nov 12, 2021 at 18:25
  • @TylerJensen if you have metal conduit, you shouldn't be using a plastic box. If you have a plastic box then it's obviously not acting like a ground.
    – JPhi1618
    Nov 12, 2021 at 18:27
  • I purchased when I thought I had a ground. If I get a metal box and self grounding outlet should I be in the clear? Nov 12, 2021 at 18:33
  • @TylerJensen the metal box will need to be properly and tightly connected to the metal conduit, and you do need to verify the continuity of the ground once that is done. Then you should be good to go with a self-grounding outlet.
    – JPhi1618
    Nov 12, 2021 at 18:35
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    There is no existing metal box, there is no cord, the power cord was removed entirely. The conduit was attached directly. Nov 12, 2021 at 20:50
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This appears to be armored cable, not conduit, but yes, you have a grounding means

From the undersized bare wire bonding strip and paper packing, I can tell that this is a (fairly modern) armored cable, not a case of wires in conduit. As a result, you'll need to use an armored cable connector (complete with "redhead" bushing or insulated throat) to connect it to your garage door opener. If the opener knockout is in plastic, not metal, you'll need to use a connector that provides a screw for attaching a bonding jumper over to the garage door opener's grounding terminal.

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  • I am not connecting direct to the garage door opener, I am creating an outlet. I am using the self grounding outlet, into a metal box, with a metal cover. The connector for the box and pipe is a metal, I believe it is called a Halex1/2 in. Flexible Metal Conduit (FMC) Squeeze Connector. Everything feels pretty solid and my ground tester is showing that it is correct. Could that be wrong? Nov 14, 2021 at 20:01
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    Your setup should be fine then, since you have the receptacle in there to pick up ground from the box via the self-grounding ears, and the box is grounded via the connector Nov 14, 2021 at 20:46
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Verify that the conduit was purposefully and correctly installed to provide a ground path, then yes you can use it for that.

Sounds like you may have a 240V motor. Because it's hard wired with two phases. Do you? Do you have an unusually large heavy door? Not a typical residential one? If so, buy the replacement before installing the outlet.

Finally, if you buy an outlet that will be installed in the ceiling, buy a very high quality one. The 99-cent outlets from hardware superstores may allow the motor plug to jiggle free when ceiling-mounted.

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  • I have a standard residential door and it is the standard Chamberlain 1/2 horsepower from Home Depot. The opener I am replacing is the basic 1990's Craftsman. I don't think it should be out of the ordinary. Nov 12, 2021 at 18:27
  • @TylerJensen having a black and red wire for a garage door opener is the only thing odd. It could be that one of the wires is controlled with a light switch and the other one is always hot, so verify that before connecting. Either the back or red will be unused, and I assume was unused by the old opener?
    – JPhi1618
    Nov 12, 2021 at 18:37
  • I have black, white, and red. I assumed that the red was for light switch. Nov 12, 2021 at 18:39
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    Don't assume anything. Ever. Get a voltmeter and learn how to use it before you mess with wiring. Or hire somebody who knows how.
    – Kyle B
    Nov 12, 2021 at 18:42
  • @KyleB I got my multimeter out. If I touch black and white I get 120v if I touch black and red I get 120v. If I touch red and white I get 0. That is what I am hoping for correct? Nov 12, 2021 at 19:38

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