#12 THHN cable assembly without a jacket.

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infinity

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celtic said:
infinity said:
How can 15 hot legs share one neutral?

I give up....how?


Is there an echo?
iwire said:
infinity said:
When can you run 15 hot legs and one neutral through a crawl space without conduit?

Never?

Some asked where you could buy or order this stuff, which seems to imply that if someone made it that it would be code compliant to use it.
 

iwire

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From the handbook. :wink:

commonneutral.JPG

A 120/240-volt, single-phase, 3-wire system (branch circuits rated at 20 amperes; maximum unbalanced current of 80 amperes).
 

winnie

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If we assume that a shared neutral circuit is appropriate in this instance, the shared neutral needs to have a derated ampacity equal to the maximum possible unbalanced current. Thus we'd be looking at using a 4/0 at a minimum, assuming single phase, balanced load on the legs, and 15A per circuit.

That link to the custom cables was quite interesting. We could get cables made up with 2 #14 and 3#12s for common a common neutral feed to a dishwasher, disposal, and receptacle.... :) ;) ;-)

-Jon
 

infinity

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iwire said:
From the handbook. :wink:

commonneutral.JPG

A 120/240-volt, single-phase, 3-wire system (branch circuits rated at 20 amperes; maximum unbalanced current of 80 amperes).


Isn't this an illustration of an outside circuit under Article 225? This would not apply to circuits within a crawlspace.
 

iwire

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infinity said:
Isn't this an illustration of an outside circuit under Article 225? This would not apply to circuits within a crawlspace.

Yes it is from 225.

Can you cite a section that generally prohibits it?

Don had a response to a proposal that basically said its prohibited but the code itself does not say that. :lol:
 

izak

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HEY, why doesnt he MAKE it up himself with the appropriate (or inappropriate) conductors and put it all in FLEX!!!

thats basically what he wants anyway, to get away from running conduit when he can pull in a hose, so let him pull in a corrugated Aluminum hose
 

infinity

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celtic said:
infinity said:
How can 15 hot legs share one neutral?

Trevor...in THIS case (hconant's OP) - would these circuits be considered MWBCs?

I'm thinking YES.


The problem that I have with this is that Bob's post shows an arrangement for one large neutral and multiple circuits under Article 225. Article 225 is for outside circuits. IMO this does not apply to an installation within a building. If this were an acceptable standard installation practice than there would be no need for the explicit approval of this installation solely for outside circuits. IMO this is one time where the "if it doesn't say that you can't, means that you can" rule doesn't apply.
 

iwire

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Trevor.....I hit quote this time. :oops: :lol:

infinity said:
IMO this is one time where the "if it doesn't say that you can't, means that you can" rule doesn't apply.

So just how do we know when "if it doesn't say that you can't, means that you can" rule doesn't apply?

What other things can't we do that are not directly prohibited?

This to me is a huge issue.

Nowhere in the NEC will you find anything that says we can not use a neutral as per the diagram I posted.

IMO this means we have an unneeded allowance in 225 to do so.

There is no safety reason not to allow the use of one large common neutral although I do not see it as economically attractive.
 

infinity

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IMO this means we have an unneeded allowance in 225 to do so.


Basically that was my point. The one specific allowance for this type of installation is under the heading of Lighting Equipment Installed Outdoors. Seems plausible to me, and as you've stated, that if the practice were generally acceptable we would have a specific code Article allowing it or not have 225.7 at all. I agree that the NEC does not say in Article XXX that you can only run one neutral for every two or three circuits, but it does say that in 225.7(B) you can run any number of circuits providing the neutral is sized properly. IMO this limits those installations solely to the parameters of 225.7.
 

iwire

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Trevor.

IMO it is a CMP mistake.

225.7 Can only allow something in covered by 225.

It can not be used to prohibit installations covered by other articles.

Unless a code section in say 200 or 300 can be shown that prohibits the practice it must be allowed regardless of 225.7s specific allowance.

Laws can not work another way.
 

BarryO

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infinity said:
When can you run 15 hot legs and one neutral through a crawl space without conduit?

When you've gotten an NRTL to certify your crawlspace as a Listed Raceway. ;)
 
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