From a double pole 20-amp breaker, I ran 12/3 w/g to a quad box with a 120 receptacle and a 240 receptacle. Red wire from one pole of the breaker to the 240, ground to the grounds, white to neutral bar in the panel and then the 120 outlet, and black from the other pole of the breaker to the box where it's pigtailed and split to the 120 and 240. The inspector failed me because this "produces uneven loads on the breakers".

I'm confused because everything I've read/seen indicates that this is exactly how to run such a circuit and the inspector could not well explain the problem or point it out in the code. Worse case if I run a tool drawing 20 amps on the 240 and plug something in drawing 10amps on the 120, both poles trip no harm no foul. I don't understand the problem or what exactly in the code I violated. He wants me to add another breaker, pull another wire, and put the 120 on its own hot.

  • Similar: diy.stackexchange.com/questions/77451/…
    – isherwood
    Jul 27, 2018 at 18:51
  • Also: diy.stackexchange.com/questions/102576/…
    – isherwood
    Jul 27, 2018 at 18:53
  • Are the breakers two 1-pole breakers that are handle-tied (and therefore only common maintenance shutoff)? Or are they a single 2-pole breaker that is common trip? Jul 27, 2018 at 20:15
  • 2
    It might be clearer for the inspector if you split the 120V receptacle (broke off its hot tab) and fed one outlet from red and the other outlet from black. That is more of a classical MWBC. As it looks now, it doesn't "look like a MWBC", it looks like you tapped a 120V circuit off a 240V. Jul 27, 2018 at 20:18
  • 1
    It's a single 2-pole breaker with a common trip.
    – tb510
    Jul 27, 2018 at 21:23

1 Answer 1


According to 210.4.c of the NEC MWB shall supply only line to neutral loads. With 2 exceptions. #1 supplies only 1 utilization equipment. #2. All ungrounded conductors opened are opened simultaneously by the branch circuit OCD. Because of this wording many inspectors won't allow line to line to be used but it is legal , if you have a NEC hand book you can even see an example exhibit 210.2 that I have used in the past for an air conditioner and standard outlet in my case it was a 20 amp 240/120 outlet. How do they know what you are going to plug into it?

  • I don't understand what this answer is getting at. If there is a 12/3 cable from a 2-pole breaker leading to a duplex receptacle with broken tab on hot, red hot on one and black on the other, does the NEC allow connecting two 12/2 cables (hot from red on one and hot from black on the other? Jul 28, 2018 at 21:14
  • I believe there are 2 separate outlets in this case but not sure, I have had the same problem in the past because of the wording but after showing the inspector the the exhibit in the hand book he changed his opinion. Even though they were separate outlets in a 4×4 box a 20 amp 120 and a 20 amp 240 is the same as a duplex split but it cost 1/4 of the single duplex or I think this is what the question is asking.
    – Ed Beal
    Jul 28, 2018 at 23:20
  • Yes it was 2 separate outlets in the box 1 20amp 120 / 1 20 amp 240. Red only goes to the 240. Black is split to the 120/240. The tab on the 120 was intact. I didn't see the point in breaking the tab (there isn't one anyway -- GFI outlet bc its a garage) and splitting the red to other half. I'm never going to run 3 tools at the same time on all 3 outlets.
    – tb510
    Jul 29, 2018 at 0:33
  • Pull up the NEC hand book 210.2 as I said and call the inspector (most inspectors use the hand book) you have done it right but as I said most inspectors need the pictures in the hand book for something they haven't seen a thousand times!.
    – Ed Beal
    Jul 29, 2018 at 1:33
  • As @Harper commented maybe you should just split the hot on the 120 V receptacle (break the tab) and feed hots separately. It wouldn't cost anything and it would give the symmetry that the inspector wants. Jul 29, 2018 at 18:06

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