Sharing Neutrals

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infinity said:
Well I know exactly what is meant by "Circuits where two or three phases share a single conductor neutral" and it's not even close to what you've posted. :roll:
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You believe the spec' is referring to a MWBC, and you are likely correct. But it is an assumption, which doesn't say much for it being a specification... let alone in a trade where assumptions can get you very dead.
 
Smart $ said:
You believe the spec' is referring to a MWBC, and you are likely correct. But it is an assumption, which doesn't say much for it being a specification... let alone in a trade where assumptions can get you very dead.
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I'm starting to think that you're trolling, if you were a first year apprentice I would cut you some slack.
 
Smart $ said:
You believe the spec' is referring to a MWBC, and you are likely correct. But it is an assumption, which doesn't say much for it being a specification... let alone in a trade where assumptions can get you very dead.
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That's exactly right.

One could assume they wanted the #10 neutral just in case 2 or more circuits happened to end up on the same phase.
In which case no handle ties would be needed at all on the branch circuits of this project.

JAP>
 
Smart $ said:
Well if I am trolling, it appears to be working... :blink::D:slaphead:
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Yea, and by the way, what did you mean when you called me "pedantic" ?

I need to know whether in need to be offended or not.... :)


JAP>
 
jap said:
Yea, and by the way, what did you mean when you called me "pedantic" ?

I need to know whether in need to be offended or not.... :)


JAP>
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Google it... so you don't have to take my word for it. :p

If you don't, then you should be offended. :D
 
Smart $ said:
Google it... so you don't have to take my word for it. :p

If you don't, then you should be offended. :D
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Just did,,, and I'm guilty.
I am going to try and use that phrase more often now.

It just sounds cool....

JAP>
 
jap said:
Just did,,, and I'm guilty.
I am going to try and use that phrase more often now.

It just sounds cool....

JAP>
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Winston Churchill is said to have said to a grammarian who criticized him for ending a sentence with a preposition:
"That sir, is arrant pedantry, up with which I shall not put!"
 
GoldDigger said:
Winston Churchill is said to have said to a grammarian who criticized him for ending a sentence with a preposition:
"That sir, is arrant pedantry, up with which I shall not put!"
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I'm with Winston.


JAP>
 
JFletcher said:
yeah, looks like MWBC are allowed per this job spec, but unless it's all EMT/conduit no one is going to use it. I dont think anyone even makes MC with 2-3 14ga ungrounded and a 10ga neutral. Wouldnt the ground need upsizing as well? Maybe super-neutral 12ga exists, havent ever looked for it. Probably not commonly stocked and probably not cheap.

yes, needs a handle tie and conductors not in a cable assembly have to be grouped in the panel.

There is absolutely no reason to use #14 hots with a 10 neutral. Ever.

Seriously long runs where everything is #10 for VD makes the most sense, tho that spec doesnt state #10 be used for ungrounded conductors too
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well if you were gonna run 12/3 MC for your branch circuits but couldn't because of the #10 neutral reuquirment why wouldn't you just run 10/3? Why would you run 12/2 a pick up one circuit?
 
jap said:
Because post #2 stated it as a MWBC which that would all depend, and , would also need a second look at the size of the neutral should the 3 circuits happen to be all on the same phase I would think, by the way that spec is worded.


JAP>
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That would be a violation
 
jap said:
Which would be the case if 2 or more circuits were on the same phase, in which case your not dealing with a MWBC by definition.

JAP>
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Ok I know ..dumb question. When are circuits on the same phase....1,3,5,7 etc.. are the same phase? What would constitute different phases?
 
jap said:
And I bet there are several projects with the neutral loaded up simply because of this ambiguous spec.
Its when you go to try and find an approved handle tie for the circuits on the same phase is when it becomes interesting. :)

JAP>
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I bet! good point!
 
mstrlucky74 said:
well if you were gonna run 12/3 MC for your branch circuits but couldn't because of the #10 neutral reuquirment why wouldn't you just run 10/3? Why would you run 12/2 a pick up one circuit?
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Better question, why spec a #10 neutral for 15A circuits? Running two of the same phase hot on a neutral isnt allowed anyway.

Why not install 10/3 from a single phase panel (or for a single phase circuit) when 12 would do? Material cost, installation time, weight, waste of materials.

Someone wanna calculate the horrendous PF non linear loads would be to actually need a 10ga noodle on a 3ph 15a circuit, or a 20? I can maybe see a 10 neutral on 12 ungrounded, but not on 14. Im sure the job spec elsewhere prohibits 14, so no big deal really, if it's all conduit.

Otherwise I'll just pull something like this:

https://www.gexpro.com/steel-armor-...d-10-2-neutral-12-2-ground-250/product/149773

and not care how much extra it costs. Not my dime.
 
Thanks Smart$ for the ground info.

jap said:
The way it reads you can share but to me its worded wrong.

The spec says nothing about a multiwire branch circuit or circuits on different phases.

Going by strictly what is reads could apply to 2 or 3 circuits on the same phase.

JAP>
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Going by the NEC, two or more hots on the same phase sharing a neutral would be parallel conductors and a violation in the case of 15 or 20A circuits.
 
mstrlucky74 said:
Ok I know ..dumb question. When are circuits on the same phase....1,3,5,7 etc.. are the same phase? What would constitute different phases?
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Depends how you number your circuits :)
Better to look at it as to which buss the circuit is connected. For a MWBC you want A-B-C (Or A-B on single phase).
 
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