Quick question for a newbie. I have a 2 gang box with 2 light switches installed. One switch is wired with a neutral. The other switch has no neutral. I'd like to swap the switch wired without a neutral to a timer switch (aka smart switch). Why can't I tie the neutral from the other switch circuit to the smart switch neutral? Neither circuit is GFCI.
Wiring for dummies question: all neutrals the same?
- Thread starter s14kev
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Are you sure it is a neutral? Could be a 3-way switch where the white was not reidentified.
Shiftless
Well-known member
Let’s wait for a pro to answer that one.
In the meantime, I’ll say that often switches are wired with NM cable and wired in a manner where the white wire should be painted black. If the installer was too lazy or ignorant to do that, your white wire might not really be a neutral.
What say the sparkies??
Edit: Thanks Norcal...looks like both of us posted at the same time.
In the meantime, I’ll say that often switches are wired with NM cable and wired in a manner where the white wire should be painted black. If the installer was too lazy or ignorant to do that, your white wire might not really be a neutral.
What say the sparkies??
Edit: Thanks Norcal...looks like both of us posted at the same time.
Dagny
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yes but it shouldn't be hooked to any of the screws if it is a neutral.
jeffmattero76
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If a white wire is hooked to a switch, it is most likely not a neutral. It is a "switch loop" or a 3way switch. Pictures would help.
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Sorry. My initial post wasn't too clear. There are two switches in the same 2 gang box. One circuit is wired like the picture below with no neutral and the other is wired like the picture with neutral. I want to put a timer switch (which needs a neutral) on the circuit wired with no neutral. Can I tie in the neutral from the other circuit to do this?
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jeffmattero76
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If the two switches are on different circuits, by code, the answer is no. Current code states that the neutral conductor must run in the same cable as the hot conductor.
That being said, it will work, but will not be code compliant as I understand it. The two breakers for these circuits should be one below the other, and the handles of the breakers must be tied together. I have rental properties that had a similar wiring scheme. I don't know for sure, but I am guessing that it was code compliant when installed 60 years ago.
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That being said, it will work, but will not be code compliant as I understand it. The two breakers for these circuits should be one below the other, and the handles of the breakers must be tied together. I have rental properties that had a similar wiring scheme. I don't know for sure, but I am guessing that it was code compliant when installed 60 years ago.
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redidbull
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The difference in those two pics is where the power comes in. One shows the 110v coming into the switch box which has the neutral going straight through to the light. The second has the 110v going into the light box so the neutral does not make it to the switch because it is not needed. It all depends on where the power enters. Jim
MikeF2316
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If they're on different breakers, it would be possible for the circuit using the neutral to be putting 12 amps (using an example) on the neutral. Adding the neutral for the other circuit connected to an electronic switch will add next to no current. But then maybe later someone else could something else into that circuit that adds appreciable neutral current, putting that neutral wire over its current rating. Or (extremely unlikely) the electronic switch could fail in such a way to cause neutral current.
If they're on the same breaker, you would create an interesting problem for our hypothetical future person when the breaker starts tripping for apparently no reason.
And of course, as mentioned it's against code.
All that said, being human, I'd probably use that neutral with the idea I'd take that switch out before I move.
If they're on the same breaker, you would create an interesting problem for our hypothetical future person when the breaker starts tripping for apparently no reason.
And of course, as mentioned it's against code.
All that said, being human, I'd probably use that neutral with the idea I'd take that switch out before I move.
jeffmattero76
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If they are on different breakers that are one below the other they are on different phases. As such, the shared neutral will only see the DIFFERENCE in the current. In other words, if one circuit is drawing 13 amps and the other is drawing 10 amps, the shared neutral would only see 3 amps.
If, on the other hand, both circuits were on the same phase, the neutral would see 23 amps. Assuming 14 gauge wire, it is only allowed to carry 15 amps. Thus, you have a potential for a fire.
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If, on the other hand, both circuits were on the same phase, the neutral would see 23 amps. Assuming 14 gauge wire, it is only allowed to carry 15 amps. Thus, you have a potential for a fire.
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MikeF2316
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Right, all my scenarios were worst case. If they're on opposite phases, then the only issue is with code. And if currently they are on different breakers and the same phase, moving one of the wires to the opposite phase would be advisable. Tying the breakers would be a good idea too.
pentavolvo
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Not saying it’s code but stuff like this is done all the time and in my opinion is a hell of a lot safer then using the ground wire
AntonLargiader
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The diagrams show that the white wire isn’t actually a neutral. How about a pic of what you actually have?
Milton Shaw
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A wire, regardless of color, is only a neutral when it is connected to neutral in the main box, otherwise it could be current carrying conductor. Always measure and check before you assume its a neutral. Color codes in old construction or handyman DIY cannot be trusted.
AntonLargiader
Well-known member
Nothing can really be trusted. In my old commercial building I had a neutral for a circuit that was fed from a different panel. My whole box is de-powered and a neutral is carrying current...
Slowgsr
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No you cannot. Same breaker, same circuit still no. Neutral needs to be in the same cable/conduit controlling the device which your switching.
theoldwizard1
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Current code requires that all boxes have a neutral and a ground, irregardless if the feed hits the switch box or the load box first. In the case of your first picture, where power goes to the load box, you need 3 conductor (plus ground) going to the switch box.
This way "smart" switches or "smart" loads have hot and neutral. This is why ovens and dryers are now 4 conductor.
If the wire is there already, you are grandfathered.
This way "smart" switches or "smart" loads have hot and neutral. This is why ovens and dryers are now 4 conductor.
If the wire is there already, you are grandfathered.
wyliesdiesels
Well-known member
A neutral is considered a current carrying conductor.
Just because it *looks* like the same as the picture doesn't necessarily means they are the same. Regular light switch does not have a connection for neutral. The picture that you are referring to is from a website talking about smart switches. Unless your current switch is a smart switch, or a digital timer, chances are that the "extra" wire coming out from that switch is not a neutral wire.
You have to be able to describe what kind of switches you have if you want people to help you.