MWBC using two 12-2

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Ponchik

Ponchik

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Location
CA
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Electronologist
12-3 cable from the load ends in a junction box in crawl space, then two 12-2 from the panel are being used to power the 12-3. The two 12-2 are on a common trip breaker.

Any issues with this install besides the parallel neutrals?
 
edward said:
12-3 cable from the load ends in a junction box in crawl space, then two 12-2 from the panel are being used to power the 12-3. The two 12-2 are on a common trip breaker.

Any issues with this install besides the parallel neutrals?
Click to expand...

Is the 12-3 really 3 conductors and a ground?

It seems safe to me but not code compliant.
 
Aside from possibly paralleled neutrals, 300.3, and possibly 210.4(D). Im guessing the electrician ran out of 12/3 and used the 2 12/2 to finish the job. I dont see a problem safety wise but it's not code-compliant.
 
infinity said:
So the 2-12/2 cables have their neutrals in parallel or is only one neutral used?
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Both neutrals are used and they are ziptied together in the panel indicating they are a family and are being used as a MWBC. satisfies 210.4(D) even though 210.4(d) does not specifically apply to this.

petersonra said:
Is the 12-3 really 3 conductors and a ground?

It seems safe to me but not code compliant.
Click to expand...

12-3 blk,red,wht, gnd

As I mentioned earlier the only issue is paralleled neutral, also circuit conductors NOT in the same cable.

But I don't see it as a hazard.
 
edward said:
Both neutrals are used and they are ziptied together in the panel indicating they are a family and are being used as a MWBC. satisfies 210.4(D) even though 210.4(d) does not specifically apply to this.



12-3 blk,red,wht, gnd

As I mentioned earlier the only issue is paralleled neutral, also circuit conductors NOT in the same cable.

But I don't see it as a hazard.
Click to expand...

Is it a hazard, maybe, maybe not, but it still is not permitted by the NEC. As far as the two neutrals zip tied in the panel if I were to open the panel and saw two neutrals zip tied together I would have no idea why.
 
infinity said:
Is it a hazard, maybe, maybe not, but it still is not permitted by the NEC. As far as the two neutrals zip tied in the panel if I were to open the panel and saw two neutrals zip tied together I would have no idea why.
Click to expand...

I think the electrician's experience + the zip ties + the common trip breaker + a note on the panel directory should give it away as a MWBC. But I do agree it violates two NEC code sections.
 
resistance said:
Im not sure this is correct if I read the question right!?
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You are just required to bring them through the same KO.

300.3(B) Conductors of the Same Circuit.
All conductors of the same circuit and, where used, the grounded conductor and all equipment grounding conductors and bonding con-
ductors shall be contained within the same raceway, auxil-
iary gutter, cable tray, cablebus assembly, trench, cable, or
cord, unless otherwise permitted in accordance with
300.3(B)(1) through (B)(4).

(3)Nonferrous Wiring Methods. Conductors in wiring
methods with a nonmetallic or other nonmagnetic sheath,
where run in different raceways, auxiliary gutters, cable
trays, trenches, cables, or cords, shall comply with the provi-
sions of 300.20(B).
Click to expand...

300.20 Induced Currents in Ferrous Metal
Enclosures or Ferrous Metal Raceways

(B) Individual Conductors. Where a single conductor
carrying alternating current passes through metal with mag-
netic properties, the inductive effect shall be minimized by
(1) cutting slots in the metal between the individual holes
through which the individual conductors pass or (2) passing
all the conductors in the circuit through an insulating wall
sufficiently large for all of the conductors of the circuit.
Click to expand...
 
infinity said:
Is it a hazard, maybe, maybe not, but it still is not permitted by the NEC. As far as the two neutrals zip tied in the panel if I were to open the panel and saw two neutrals zip tied together I would have no idea why.
Click to expand...

edward said:
I think the electrician's experience + the zip ties + the common trip breaker + a note on the panel directory should give it away as a MWBC. But I do agree it violates two NEC code sections.
Click to expand...

The addition of the note would make it more obvious. :)
 
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