Sharing Neutrals

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mstrlucky74

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So the spec looks to me as if we are allowed to share neutrals. Agree? Would need a circuit breaker handle tie, correct?

Thanks.
 

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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
 
mstrlucky74 said:
So the spec looks to me as if we are allowed to share neutrals. Agree? Would need a circuit breaker handle tie, correct?

Thanks.
Click to expand...

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>
 
mstrlucky74 said:
So the spec looks to me as if we are allowed to share neutrals. Agree? Would need a circuit breaker handle tie, correct?

Thanks.
Click to expand...

Yes, you need a handle-tie and can share the neutral (MWBC) when using #10 for the neutral conductor and either #12 or #10 for the phase conductors.
 
If the circuits don't have voltage between them the we are not talking about MWBC to begin with.

Jap>
 
JFletcher said:
... Wouldnt the ground need upsizing as well? ...
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EGC... no, assuming we are discussing a grounded neutral here. Required upsizing of the EGC is contingent upon the size of the ungrounded circuit conductors being greater than the minimum sufficient size.
 
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>
 
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>
 
infinity said:
Ok but how is that related to what MrLucky posted?
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The spec doesn't specifically say the two or three ungrounded conductors are of differing phases. jap is being pedantic... but FWIW, the spec' is ambiguous (defeating the purpose of a spec') and brings it out of people that must be oriented to detail to do good work.
 
Smart $ said:
The spec doesn't specifically say the two or three ungrounded conductors are of differing phases. jap is being pedantic.
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I think that we all know what is meant by "Circuits where two or three phases share a single conductor neutral."
 
If a multi wire circuit does not fit the definition of a MWBC, such as 2 or more ungrounded conductors on the same phase, are you still required to follow all of the rules for a MWBC ?

JAP>
 
infinity said:
I think that we all know what is meant by "Circuits where two or three phases share a single conductor neutral."
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Two or three A phases... or maybe B phases... could even be C phases... then again perhaps A and B... maybe B and C... ah heck, let's just make 'em ABC.

Yes, ambiguous. :p
 
infinity said:
How is this not a MWBC?
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By Definition, if the circuits don't have voltage between them, which is the case if 2 or more circuits happen to be on the same phase, then its not a MWBC

The Spec is confusing.

JAP>
 
Smart $ said:
Two or three A phases... or maybe B phases... could even be C phases... then again perhaps A and B... maybe B and C... ah heck, let's just make 'em ABC.

Yes, ambiguous. :p
Click to expand...

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>
 
Smart $ said:
Two or three A phases... or maybe B phases... could even be C phases... then again perhaps A and B... maybe B and C... ah heck, let's just make 'em ABC.

Yes, ambiguous. :p
Click to expand...


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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