Two (2) 12/2 UF-2 as feeder to accessory structure?

Merry Christmas

lakee911

Senior Member
Location
Columbus, OH
Can two (2) runs of 12/2 UF-2 be used as feeder to an accessory structure? Feed from a 2P 20A CB. Thanks.

Though odd, I can't find where the code would disallow it. Parrallel neutral is just redundant and not necessarily required.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Agree. A multiwire branch circuit would be allowed

Part II. Buildings or Other Structures Supplied by a Feeder(s)
or Branch Circuit(s)
225.30 Number of Supplies. A building or other structure
that is served by a branch circuit or feeder on the load side of a
service disconnecting means shall be supplied by only one
feeder or branch circuit unless permitted in 225.30(A)
through (E). For the purpose of this section, a multiwire
branch circuit shall be considered a single circuit.
Where a branch circuit or feeder originates in these additional
buildings or other structures, only one feeder or branch
circuit shall be permitted to supply power back to the original
building or structure, unless permitted in 225.30(A)
through (E).
 

winnie

Senior Member
Location
Springfield, MA, USA
Occupation
Electric motor research
IMHO only one circuit is permitted, but that can be a 'Multiwire branch circuit '.

In general all conductors of a circuit must be run in the same conduit or cable. However I believe you can use two non-metallic cables side by side for a single circuit.

Jon
 

tom baker

First Chief Moderator
Staff member
IMHO only one circuit is permitted, but that can be a 'Multiwire branch circuit '.

In general all conductors of a circuit must be run in the same conduit or cable. However I believe you can use two non-metallic cables side by side for a single circuit.

Jon
How does that meet the definition of MWBC and all conductors in the same raceway or cable?
 

tallgirl

Senior Member
Location
Great White North
Occupation
Controls Systems firmware engineer
It would need to be a MWBC to qualify as a single circuit so only one neutral.
But for how long? Sooner or later there are going to be "2" neutrals unless the MWBC feeds nothing but split-wired receptacles ...

If you look at ... the video ... eventually L1 and L2 are no longer in the same cable. All that's being proposed is separating L1 and L2, and a neutral to go with each, a lot sooner than the example Mike gives in ... this video.

 

winnie

Senior Member
Location
Springfield, MA, USA
Occupation
Electric motor research
How does that meet the definition of MWBC and all conductors in the same raceway or cable?

Wouldn't 300.3(B)(3) apply to UF cable? If I have 2 UF cables side by side, always passing through the same holes if entering metal enclosures, then I think you could use conductors from both cables to form a single circuit. Black from cable A to one pole of a double pole breaker, black from cable B to the second pole, white from either cable as neutral, white from other cable unused, and both grounds used.

-Jon
 

lakee911

Senior Member
Location
Columbus, OH
Wouldn't 300.3(B)(3) apply to UF cable? If I have 2 UF cables side by side, always passing through the same holes if entering metal enclosures, then I think you could use conductors from both cables to form a single circuit. Black from cable A to one pole of a double pole breaker, black from cable B to the second pole, white from either cable as neutral, white from other cable unused, and both grounds used.

-Jon
That would be another way with two cables and no paralleling.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
But for how long? Sooner or later there are going to be "2" neutrals unless the MWBC feeds nothing but split-wired receptacles ...
I was talking about the supply conductors from one structure to another. The second structure would have a disconnecting means so you could have two neutrals after that point.
 

tallgirl

Senior Member
Location
Great White North
Occupation
Controls Systems firmware engineer
I was talking about the supply conductors from one structure to another. The second structure would have a disconnecting means so you could have two neutrals after that point.
I was picking nits.

MWBCs work electrically because the neutral currents cancel at the point where they are connected, wherever that is, even if it's inside the panel where the MWBC originates. They work financially because, as Mike says in that video, they save the cost of a wire.

This isn't an MWBC problem, it's a "separate structure" problem.


What's described is common data center wiring where 120/208 is run under the floor and single phase whips are taken off a box with no intervening disconnecting means. It's less common in pre-wired office cube partitions (another example given) because all of the phase conductors tend to be present. But for data centers? It's 120/208 Wye to a box under a rack, and if the rack doesn't need all the available power and only has 120 volt loads, all that's brought up through the floor is a single phase, with it's own neutral, and there's no disconnecting means below the floor, only at the PDU.
 
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