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Discussion Starter · #1 · (Edited)
I'm replacing the knob and tube in my home and I'd like to have a "double light switch box" (I'm sure there's a better name for that) where each switch is for a light on a different branch circuit. The wiring would be COMPLETELY separate: not sharing neutrals, grounds, etc. I would expect this to be fine (and common!), but since I've never had different circuits (separate breakers) occupy the same box, I thought I'd ask. If this can't be done, then I'll put 2 single light switch boxes right beside one another, but that seems silly.
 

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That's fine.

In fact they make boxes with partitions to help with that sort of thing.

You have the right idea re: neutrals.

However, safety grounds can commingle.

Since the devices are on different yokes, the breakers do not need to be handle-tied.
 

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Discussion Starter · #3 ·
That's fine.

In fact they make boxes with partitions to help with that sort of thing.

You have the right idea re: neutrals.

However, safety grounds can commingle.

Since the devices are on different yokes, the breakers do not need to be handle-tied.

Thank you! Is there a consensus on whether it's better to have the grounds tied together or separate? I've already purchased a standard box, but I can get one with a separator if that's best practice?
 

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Re: sharing neutrals. (If I'm understanding the question correctly) There's no need to run 2 feeders from 2 different breakers, unless you just want to. One 15 or 20 amp breaker can function on two lights with two separate switches. Tie the neutrals together, terminate on each light.

Maybe I misuderstood the OP.
 

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Discussion Starter · #6 ·
Re: sharing neutrals. (If I'm understanding the question correctly) There's no need to run 2 feeders from 2 different breakers, unless you just want to. One 15 or 20 amp breaker can function on two lights with two separate switches. Tie the neutrals together, terminate on each light.

Maybe I misuderstood the OP.
I realize that the two lights could be powered by the same feeder, but I want them to be on separate feeders.
 

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I've never heard or read that the grounds from separate circuits have to be touching when in the same box. As long as each has a consistent patch back to the panel, it is the same as if they are connected there. I would like to know the reference number.
What you are planning is done all the time. I would label the back side of the cover to indicate such.
 

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I've never heard or read that the grounds from separate circuits have to be touching when in the same box. As long as each has a consistent patch back to the panel, it is the same as if they are connected there. I would like to know the reference number.
What you are planning is done all the time. I would label the back side of the cover to indicate such.
It wasn't said that they HAD to be, it was said that the MAY be. In either case, they should be terminated on the switches.

There's no need to cause confusion here, and create more replies than necessary . The two who replied to him know what they're doing.

Brian: follow Seharper, and rj's advice.
 

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I've never heard or read that the grounds from separate circuits have to be touching when in the same box. As long as each has a consistent patch back to the panel, it is the same as if they are connected there. I would like to know the reference number.
What you are planning is done all the time. I would label the back side of the cover to indicate such.
250.148 requires all grounding conductors in a box be connected together.
 

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Do you necessarily need seperate neutrals? You could use 2 circuits and share a neutral. To each his own i guess.
You really, really, really need to separate neutrals from 2 different circuits. Really. Always.

There's no "to each his own" to it; it's not a style thing; crossing separate circuits' neutrals is bad.

I'm not talking about MWBCs.
 

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I've never heard or read that the grounds from separate circuits have to be touching when in the same box. As long as each has a consistent patch back to the panel, it is the same as if they are connected there. I would like to know the reference number.
What you are planning is done all the time. I would label the back side of the cover to indicate such.
This is why you shouldn't be giving advice on an electrical forum.
 
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Do you necessarily need seperate neutrals? You could use 2 circuits and share a neutral. To each his own i guess.

And I'll say it again because it is very dangerous.

NO-this can not be done. Unless this is set up as a MWBC sharing neutrals can cause a neutral overload.


Brian85-Please Google this. You will see how dangerous this is to do sharing neutrals.
 

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Discussion Starter · #17 ·
Thanks everyone. Based on the great feedback the two switches will ONLY be connected by their 2 ground wires.


A follow-up, related question: Is it possible that 1 of the 2 circuits in this is 15 amp and the other is 20 amp? To be clear, following the advice in this thread, that would mean that a ground wire from 12-2 romex is connected to a ground wire from 14-2 romex. Nothing else in the two branch circuits would be connected in any way. I expect this is permissible, but I'm not sure whether this is bad practice.
 

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All ground wires in a box without regard to wire size or circuit rating must be connected together. So yes the 14 and 12 ground should be connected.
 
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