Is this the neutral wire that I can use?

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Old 09-20-17, 02:51 PM
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Is this the neutral wire that I can use?

I am trying to install a home automation timer switch for my outside lights, which of course requires a neutral wire. I am not certain that I have a neutral wire in my electrical box for this and wanted to make sure. The switch box serves three different switches. Two of the switches (interior 3-way lights) are on one circuit and the outside light switch is on a separate circuit. Each of the interior switches have white wires that go to them. However, I notice at the back of the electrical box is a pair of white wires that come out of the wall into the box, but are not connected to any of the switches. I am thinking that maybe perhaps this might be my neutral wire that I can use? See the attached image. So, how do I know whether this is in fact a neutral and that it is on the correct circuit so I can use it for my outside lights home automation switch? I have a multi-meter to do whatever checks are necessary. Thanks

 
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Old 09-20-17, 03:09 PM
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If you have white wires that are wirenut together they are neutrals. One way to know for sure is if you have a meter is to check for 120V from a black to those whites.
 
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Old 09-20-17, 08:24 PM
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Great, thanks so much. I will check the voltage to confirm. This gives me some hope that I can actually get my home automation system working properly!
 
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Old 09-20-17, 08:45 PM
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Welcome to the forums.

If it was one of the three way switches you were replacing with a wifi type..... you'd be out of luck as the neutral for that circuit is not there.

You'll probably see four cables in that box.
2) three wire cables.... one to each three way switch.
2) two wire cables.... two whites combined and the two blacks on the switch you are replacing.
When confirming the two whites are neutrals.... you'll also need to determine which black wire on the switch is the hot one. That goes to the new switch's black. The other black will be the load and go to the new switch's red wire.
 
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Old 09-21-17, 07:33 AM
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Great, thanks Pete. Yes, there are four cables in my box. Three of them are three-wire cables with red, black, and white wires (plus ground). And one is a two-wire cable with just black and white wires (and ground).

Two of the three 3-wire cables go to the existing 3-way switches.

For the remaining 3-wire and 2-wire cables, the whites are wire-nutted together and go nowhere else. The blacks are also wire-nutted together and then connect to the existing outdoor light switch. Finally, the remaining red wire from the 3-wire cable goes to the existing outdoor light switch.

So, given the above, I assume I can re-use the red and black wires to my new switch and also wire-nut the new switch's neutral wire to the two wire-nutted white wires (once I confirm these are actually neutral wires). And, in doing all this, I hope nothing explodes or burns down!
 
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Old 09-21-17, 10:30 AM
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Sounds like a plan.................
 
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Old 09-24-17, 03:17 PM
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Tried this wiring method but outside lights don't turn on. Not sure why!

Hmm, I thought I had wired everything correctly but my new Leviton Dimmer Switch does not turn on my lights. The green light comes on on the switch and the green dimmer lights on the switch seem to work but the outside lights don't turn on. Right now, I am very puzzled as to why. I have attached a diagram of how I have wired things. I am wondering if I did the right thing by capping off the red wire? And perhaps maybe the red wire should go to the red terminal?
 

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Old 09-24-17, 03:39 PM
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I guess I assumed the two-wire cable on the left was what went out to my outside lights. And the three-wire cable, second from left, is what is coming in from the breaker. The reason for this is that the black wire in this 3-wire cable is hot while the black on the 2-wire cable is not. So, am I making some wrong assumptions here?
 
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Old 09-24-17, 07:05 PM
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And the three-wire cable, second from left, is what is coming in from the breaker.
Except in a couple of specific situations which do not apply here a cable from the breaker will not be three conductor. It will be 2-conductor.

The reason for this is that the black wire in this 3-wire cable is hot while the black on the 2-wire cable is not.
Sounds like you used a non contact tester. They can not be used for real testing. You need to use a multimeter, preferably analog, or a test light. Disconnect the black of the cable and test to neutral or ground.
 
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Old 09-24-17, 07:34 PM
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We discussed a red and black wire on the old switch...... so yes.... there needs to be a red wire reconnected.

If you didn't connect the red wire to the new switch then that means you only have white and black connected..... is that correct ?
 
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Old 09-25-17, 10:04 AM
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Success! Thanks so much for your help. It was very much needed!

So, here's what my wiring ended up looking like now that it all works properly. It really helped me to be able to identify and verify the neutral wire as well as to confirm which of the black wires was the hot one. My home automation light switch now works perfectly!
 
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Old 09-25-17, 10:20 AM
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Looks good. Nice job.
 
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