I have a 3 gang box with 2 circuits. Power comes in for one circuit and feeds two switches. I know all 3 of those neutrals get tied together and all 3 grounds get tied together with pigtails to the switches. There is also a 14/3 coming in as a switch loop for a fixture on another circuit. I assume that neutral should just be capped off since it isn't doing anything. Does the ground for the 14/3 get tied to the other grounds or just to the switch?
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Two Circuits in Same Box
- Thread starter Al G
- Start date
n8n
Well-known member
The neutrals and grounds should all be tied together. Only exception would be if there were really two circuits in which case you'd have two groups of neutrals but from your description it sounds like these are all one circuit.
The switch leg neutral should be "live" but capped off at the switch end. Grounds should be connected the whole way. (if's actually kinda scary that you asked that)
The switch leg neutral should be "live" but capped off at the switch end. Grounds should be connected the whole way. (if's actually kinda scary that you asked that)
dfiler2
Well-known member
You may want to do a little checking, many times the white wire in a switch is not a neutral, it is the wire that sends power back to the light. Check the white wires to see if they are marked with black tape, if they are not it doesn't mean they are not hot, just that they weren't marked. Check at the light to see how the white wire is connected.
The neutrals and grounds should all be tied together. Only exception would be if there were really two circuits in which case you'd have two groups of neutrals but from your description it sounds like these are all one circuit.
The switch leg neutral should be "live" but capped off at the switch end. Grounds should be connected the whole way. (if's actually kinda scary that you asked that)
There are two circuits. One circuit feeds two of the switches. The third switch controls a switch loop to fixture on a different circuit. The power for that circuit is fed at the fixture.
You may want to do a little checking, many times the white wire in a switch is not a neutral, it is the wire that sends power back to the light. Check the white wires to see if they are marked with black tape, if they are not it doesn't mean they are not hot, just that they weren't marked. Check at the light to see how the white wire is connected.
No checking needed. It's new construction and I can see it all. The switch loop uses the black and red conductors. The white does nothing.
dfiler2
Well-known member
Got it, I believe new code requires neutral at switch, so then they would be capped off if not needed. All grounds should be connected I believe, I know it wouldn't be wrong to do it that way.
The neutral at the switch is being required for different smart equipment that require power to operate that may be installed in the future..
The neutral at the switch is being required for different smart equipment that require power to operate that may be installed in the future..
Last edited:
Mustang51js
Well-known member
If you plan on using arc fault breakers don't tie the neutrals together from two curcuits
alfredeneuman
Well-known member
You may want to do a little checking, many times the white wire in a switch is not a neutral, it is the wire that sends power back to the light.
That's exactly backwards. The white wire sends the power to the switch, and the black is the switch leg.
It's done this way so one can replace the light fixture and not have 2 white wires to deal with when hooking it up. The polarity matters on the light fixture, and if you had 2 white wires there would be no way to tell that without some kind of meter with the power turned on.
n8n
Well-known member
You may want to do a little checking, many times the white wire in a switch is not a neutral, it is the wire that sends power back to the light. Check the white wires to see if they are marked with black tape, if they are not it doesn't mean they are not hot, just that they weren't marked. Check at the light to see how the white wire is connected.
He said 14/3 for a switch leg so I assumed that it was a new run pulled with an eye towards passing an inspection under current NEC which requires a neutral be present in all switch boxes.
n8n
Well-known member
That's exactly backwards. The white wire sends the power to the switch, and the black is the switch leg.
It's done this way so one can replace the light fixture and not have 2 white wires to deal with when hooking it up. The polarity matters on the light fixture, and if you had 2 white wires there would be no way to tell that without some kind of meter with the power turned on.
Unless the installing electrician did what he was supposed to and reidentified the white that wasn't a neutral with a ring of colored tape.
Your explanation actually makes sense however and I will begin doing it as you describe in situations where I'm not repulling as it does make sense that you'd want it that way if the tape happened to fall off. However it seems it would also make sense to use red (or other color) tape on the black in that situation as that black is now no longer "always hot."
n8n
Well-known member
Got it, I believe new code requires neutral at switch, so then they would be capped off if not needed. All grounds should be connected I believe, I know it wouldn't be wrong to do it that way.
The neutral at the switch is being required for different smart equipment that require power to operate that may be installed in the future..
Neutral should be capped *at switch where it is not used* but connected at the ceiling box, in case it *is* used in the future.
alfredeneuman
Well-known member
Unless the installing electrician did what he was supposed to and reidentified the white that wasn't a neutral with a ring of colored tape.
That rule just became Code in the 2008 (2005?) edition, along with taping a white wire in a breaker box used as a hot.
Prior to that it required no identification.
RunninOnEmpty
Well-known member
The neutrals and grounds should all be tied together. Only exception would be if there were really two circuits in which case you'd
Only at the distribution panel. It likely won't blow anything if you connect them together in a junction box but it will render GFCI and such useless because GFCI works by comparing the input current (from the hot line) to the output current (on the neutral line). It's less safe. As others have said, the grounds can be connected together, but not the neutrals.
Also I would highly recommend using a label maker to note the existence of 2 circuits within the box in case someone else has to work on the system at a later date. You don't want someone turning off one circuit and assuming the junction box is cold. Hopefully that person would be smart enough to test every wire in there before touching any of them, but don't count on it.
Thanks for the replies. I had actually made up the box yesterday with all the grounds tied together and the one neutral capped off. Then I had second thoughts and decided to ask. This is the only box I have with multiple circuits.
And yes, this is being done to pass inspection for new construction.
And yes, this is being done to pass inspection for new construction.
The neutrals and grounds should all be tied together.
The neutrals should be tied together and the grounds should be tied together, but the neutrals and the grounds shouldn't be tied together.
teamextreme
Well-known member
The neutrals should be tied together and the grounds should be tied together, but the neutrals and the grounds shouldn't be tied together.
Important semantics distinction. I think everyone understood this to be the case, but probably important to point out in case someone read it literally.
Are you homeowner doing own electrical ??
Yes, with permits and inspection.