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Old 03-22-2019, 03:27 PM   #1
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Default Neutral Question

Hi gang, been a hot minute!!

I have a scenario where we are running a 50 amp 3-ph circuit that requires no neutral, however we are incorporating a few 120v control devices (contactor/timer) which will be tapped and fused-down from one of the legs (2 amps). Question is, can I run a #12 neutral with this circuit?

Ideally I would get a 208v contactor and timer and not utilize a neutral, however client has already purchased these items and insists on using them.
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Old 03-22-2019, 03:43 PM   #2
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If you are going to run a #12 neutral, why not just run a normal 120V 2-wire circuit instead of tapping and fusing it?
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Old 03-22-2019, 04:28 PM   #3
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If you are going to run a #12 neutral, why not just run a normal 120V 2-wire circuit instead of tapping and fusing it?
Well, there will be a control box, and client is adding all necessary items too, which means less wire/labor (250ft) on my end. We are basically taking over a project that they intended on doing in-house so trying to make it as painless as possible. They will do the control side.

Mainly, I want to know from code perspective whether it would be compliant...I can't see a reason it isn't so as long as it's fused within its ratings.
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Old 03-22-2019, 04:33 PM   #4
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Well, there will be a control box, and client is adding all necessary items too, which means less wire/labor (250ft) on my end. We are basically taking over a project that they intended on doing in-house so trying to make it as painless as possible. They will do the control side.

Mainly, I want to know from code perspective whether it would be compliant...I can't see a reason it isn't so as long as it's fused within its ratings.
No. Well not per the Canadian code you can’t.
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Old 03-22-2019, 04:33 PM   #5
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Question is, can I run a #12 neutral with this circuit?
No. It may not be smaller than the EGC.
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Old 03-22-2019, 04:35 PM   #6
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No. It may not be smaller than the EGC.
This makes sense. Do you happen to know code ref?
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Old 03-22-2019, 04:41 PM   #7
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Originally Posted by electricut View Post
Hi gang, been a hot minute!!

I have a scenario where we are running a 50 amp 3-ph circuit that requires no neutral, however we are incorporating a few 120v control devices (contactor/timer) which will be tapped and fused-down from one of the legs (2 amps). Question is, can I run a #12 neutral with this circuit?

Ideally I would get a 208v contactor and timer and not utilize a neutral, however client has already purchased these items and insists on using them.
Use two legs, and a transformer with nice built in fuse block.
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Old 03-22-2019, 04:45 PM   #8
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Use two legs, and a transformer with nice built in fuse block.
Yeah, there are definitely better options like what you are saying, but they are gonna use what they already purchased, which has no xfrmr included.
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Old 03-22-2019, 04:46 PM   #9
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Originally Posted by electricut View Post
Well, there will be a control box, and client is adding all necessary items too, which means less wire/labor (250ft) on my end. We are basically taking over a project that they intended on doing in-house so trying to make it as painless as possible. They will do the control side.

Mainly, I want to know from code perspective whether it would be compliant...I can't see a reason it isn't so as long as it's fused within its ratings.
I am not understanding why you would pull 1 #12 but not 2 of them. Why have to tap and fuse it?
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Old 03-22-2019, 05:08 PM   #10
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Yeah, there are definitely better options like what you are saying, but they are gonna use what they already purchased, which has no xfrmr included.
Tell them they will need to buy one. For only 2 amps, it will be small, probably fit in the same box as the contactor, and not cost much.

Do it right
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Old 03-22-2019, 05:50 PM   #11
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This makes sense. Do you happen to know code ref?
Well, shoot. Now that you've asked I can't locate it. For feeders it's easy enough and maybe that's what I was thinking of. Right now I can't find anything to justify a smaller neutral on a MWBC at all. I will keep looking (for my own sanity as well, I was pretty certain of this) but in the meantime it might be best to ignore what I said.
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Old 03-22-2019, 06:39 PM   #12
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Well, shoot. Now that you've asked I can't locate it. For feeders it's easy enough and maybe that's what I was thinking of. Right now I can't find anything to justify a smaller neutral on a MWBC at all. I will keep looking (for my own sanity as well, I was pretty certain of this) but in the meantime it might be best to ignore what I said.
Are you thinking about the service neutral?
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Old 03-22-2019, 06:47 PM   #13
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Hi gang, been a hot minute!!

I have a scenario where we are running a 50 amp 3-ph circuit that requires no neutral, however we are incorporating a few 120v control devices (contactor/timer) which will be tapped and fused-down from one of the legs (2 amps). Question is, can I run a #12 neutral with this circuit?

Ideally I would get a 208v contactor and timer and not utilize a neutral, however client has already purchased these items and insists on using them.
There are a couple good answer posted in the fourm in here and for myself .,,

I would get a properly sized transformer with fused block on it and be done with it and not have to mess with neutral conductor at all.

Oh by the way # 12 awg on 50 amp circuit is a no go ( look up at art 430 and 440 that is a starting point and there are few other codes in the mix it will pop up )
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Old 03-22-2019, 06:50 PM   #14
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Well, shoot. Now that you've asked I can't locate it. For feeders it's easy enough and maybe that's what I was thinking of. Right now I can't find anything to justify a smaller neutral on a MWBC at all. I will keep looking (for my own sanity as well, I was pretty certain of this) but in the meantime it might be best to ignore what I said.
Just keep in your mind the service neutral and feeder neutral is different item to deal with it.
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Old 03-22-2019, 07:40 PM   #15
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I have not seen a section for branch circuit neutrals and I have brought this up a few times.

It makes sense to me that in the scenario of a short circuit (hot to neutral) that the neutral should be able to carry the fault. This is why there is a minimum size equipment grounding conductor so why would a neutral be allowed to be smaller than the equipment grounding conductor?
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Old 03-22-2019, 08:26 PM   #16
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I have not seen a section for branch circuit neutrals and I have brought this up a few times.

It makes sense to me that in the scenario of a short circuit (hot to neutral) that the neutral should be able to carry the fault. This is why there is a minimum size equipment grounding conductor so why would a neutral be allowed to be smaller than the equipment grounding conductor?
Our code refers to the white wire as a grounded conductor and it needs to be sized to carry the load. An actual neutral is only a conductor that carries the unbalanced load and can be smaller than the ungrounded because of that. It can never be smaller than the bond though.
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