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#20365 - 01/13/03 03:51 PM multiwire circuit
jdevlin Offline
Member

Registered: 08/07/02
Posts: 402
Loc: welland ontario canada
Here is question that was posed today. Can anyone tell if it would violate any code.
A mutli wire circuit with both branches off the same leg using #14 wire and the neutral using #10. Since #10 is rated for 30 amp would there be a code violation.
NOTE:No one is actually trying this is was just a question that was raised.

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#20366 - 01/13/03 03:54 PM Re: multiwire circuit
HotLine1 Offline

Member

Registered: 04/03/02
Posts: 6804
Loc: Brick, NJ USA
A handle tie on the OCP???
I'm OK with the #10 neutral, and you do have 15 amp OCP on the two hots right??
John
_________________________
John

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#20367 - 01/13/03 03:56 PM Re: multiwire circuit
jdevlin Offline
Member

Registered: 08/07/02
Posts: 402
Loc: welland ontario canada
Yes 15 amp ocp. The handle tie never came up in the discusion.

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#20368 - 01/13/03 05:19 PM Re: multiwire circuit
iwire Offline
Moderator

Registered: 01/05/03
Posts: 4343
Loc: North Attleboro, MA USA
Do you mean to say both hots on the same phase?

That will make for a strange handle tie.:
_________________________
Bob Badger
Construction & Maintenance Electrician
Massachusetts

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#20369 - 01/13/03 06:05 PM Re: multiwire circuit
HotLine1 Offline

Member

Registered: 04/03/02
Posts: 6804
Loc: Brick, NJ USA
Iwire:
OK, you're awake. I should have said something like " a tandem/piggyback breaker" with a handle tie.
John
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#20370 - 01/13/03 06:47 PM Re: multiwire circuit
lighthouse Offline
Member

Registered: 01/02/03
Posts: 141
Loc: philadelphia pa 19125
jdevlin...this is one practice that i never liked.i under stand that your running less wire(cost)but if you lose the neutral you could have 240 volts going to a receptacle.

i know they do sell this cable.standard mc cable with a super neutral.but i think it/'s 3#12 and a#10 neutral and a #12 ground for a 3 phase panel .don't no if it comes in #14/w 10 neutral.

i don't see a violation here.15 amp ocp and a #10 neutral.better then the 14/3 used and someone changes the breakers around.

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#20371 - 01/13/03 07:34 PM Re: multiwire circuit
Hutch Offline
Member

Registered: 05/27/02
Posts: 383
Loc: South Oxfordshire, UK
If you're on the same leg I don't see the 240V problem with the lost neutral.

In that regard, a tied pair of breakers should be required for code but I've never seen these tied across the same leg. Can you tie your own?

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#20372 - 01/13/03 07:36 PM Re: multiwire circuit
iwire Offline
Moderator

Registered: 01/05/03
Posts: 4343
Loc: North Attleboro, MA USA
I am still confused

jdevlin said

"A mutli wire circuit with both branches off the same leg"

Article 100: Branch Circuit, Multiwire
makes clear that the hots are from different phases

If this is the case all #14s would be fine

But "with both branches off the same leg"
this would not be a multiwire branch circuit, it would be two hots of the same phase coming back on one neutral
the current would add up to potentially 30amps
never seen this done (On purpose) and my reaction would be that it is a violation,
But I do not know how to find it.

lighthouse we do this all the time with 4 wire 3H + 1N + 1G the advantages outway the problems for us.

And for the cables AFC will pretty much get whatever you need.

I just did a job using MC with 3 whites 2 greens 1 each black red blue all #10s Matched up to the office cube furniture
_________________________
Bob Badger
Construction & Maintenance Electrician
Massachusetts

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#20373 - 01/13/03 08:04 PM Re: multiwire circuit
lighthouse Offline
Member

Registered: 01/02/03
Posts: 141
Loc: philadelphia pa 19125
Hutch..your right there no way you can get 240 volts on the same circuit.i was just trying to explain this circuit on two seperate circuits breakers.myself i just don't like this practice.

iwire..office cube furniture.3 circuits w/1 isolated ground.receptacles mark a,b,c. nice you can change the receptacles to whatever circuit you like.

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#20374 - 01/14/03 04:11 AM Re: multiwire circuit
jdevlin Offline
Member

Registered: 08/07/02
Posts: 402
Loc: welland ontario canada
Please not I am not attempting to do this. It was just a discussion that came up as to wether it was a code violation or not IF it was done.

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