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I'm finding a lot of conflicting information on this, and I think the code has changed a lot over the years, and many posts in forums are about multi-wire branch circuits (or being confused with them).

Based on either NEC 2014 or 2017 (which will be adopted here in about three months), what are the specific requirements, if any, for splitting a 20A duplex outlet on the tabs and having the top fed by one 20A breaker and the bottom feed by a second 20A breaker?

In this case, there would be two hots, two neutrals, and two grounds, since I would run two 12/2 romex runs to it. I know the neutral tab needs to be broken on the receptacle and the correct neutral placed on each side for safety and for AFCI to work.

I've read all sorts of conflicting information about this, much of which seems to get confused with MWBC (probably because that is how you would feed this setup "back in the day" when AFCI wasn't required).

What are the specific and current code requirements for wiring two circuits to one duplex receptacle? Specific NEC article and section numbers would be appreciated.

To clarify, these are the types of concerns that may or may not apply:

  1. Labeling requirements. Should a warning be provided somewhere that de-energize one plug does not de-energize both?
  2. Do they need to trip together?
  3. Do the handles need to be joined (tandem breaker, 2 pole, etc)?
  4. Since they are not sharing a neutral, it should be OK for them to be on the same leg. In fact, I think it would be good practice to put them on the same leg, because then you wouldn't be able to have 240 at a box most people expect to be 120.
  5. Similarly, it seems the arc potential would be greater if the hots were on opposite legs, since there is more electromotive force, which could jump a larger air gap.
  6. Something else that I didn't think of, since the people who write the code have put lots of thought into it based of field data and electrical engineering principles.
  7. The most common application for breaking the tab is switch controlled outlets, which our usually supplied by the same branch, just one side is after a switch. In the event of receptacle failure where the hots touched, the light would just turn on. If the two hots were on different legs, it might cause bigger problems.
  8. Sometimes certain features can only be used in certain cases. For example, you must wire the screw terminal for 12ga/20a circuits, but can legally back stab 14ga/15a. I thought perhaps there may be similar rules about when you could use two separate hots on a receptacle.
  • I guess I am not sure what the question is since you are running 2 separate circuits Its not a multi wire branch circuit. You would need a handle tied breaker but that may be local req will look it up. – Ed Beal Oct 5 '17 at 18:53
  • @EdBeal I've updated the question with some of the things I thought might be an issue, like labeling requirements and handle ties. – Nick Oct 5 '17 at 20:05
  • Still not back to my books but the handle tie on the 2 breakers turns both circuits off so if working on 1 the other is also off. There is only 120v to ground yes 240 from hot to hot but not a problem as you noticed this has been done for years with MWBC. If 14 awg you can back stab but don't do it. 12 awg will be clamped or wrapped and tightened. – Ed Beal Oct 5 '17 at 20:19
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Edit NEC 2017 , 210.7 where 2 or more branch circuits supply the same yoke a means to simultaneously disconnect the ungrounded conductor At the source Knew it was in there but thought it might be local we have 28 pages of exceptions to the code for my state and even more for the county. Hope this helps 2014 NEC is the same. So it can be handle ties or common trip (common trip would be a touch safer) handle ties don't trip both circuits 100% according to UL.

  • A two-pole, common trip arc fault... now that's an expensive breaker! – Nick Oct 5 '17 at 23:44
  • @nick it's not so bad... two-pole implies both common trip and common maintenance shutoff. So it boils down to simply 2-pole AFCI. Any 240V or 120/240V load would use this, including an MWBC. – Harper Oct 6 '17 at 1:25
  • It’s a government conspiracy with the breaker manufacturers! I’m kidding!! – Craig Oct 10 '17 at 15:10
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That's just considered normal wiring

As Ed Beal points out, the only special thing is that since both recpetacles are on the same yoke, they must have a common maintenance shut-off. Because realistically, repairmen don't actaully stick a tester in both receptacles, they just probe one, and do stuff until it shuts off. Whatever does that, must shut them both off.

In the case of the ubiquitous dual NEMA 5 receptacle, you simply have two receptacles on the same yoke, and if you snap off the tabs, they are independent receptacles.

The grounding system can be blended since it comes out of the same panel, so if you are running two 12/2's instead of 12/2/2 cable, simply tie them together in the back of the box. You must pigtail them if more than 1 is involved: removing the receptacle can't sever anything else's ground.

Also if you plan to daisy chain these down to other receptacles, do not put one on the screw and one on the stab. Either pigtail, or go for receptacles like Leviton's screw-and-clamp which are designed and rated for 2 wires per terminal.

To your questions

  • 1 Warning signs? No need, an electrician is expected to measure for power being present, and any of a variety of devices (like a night light) will do this. If you wanted to give them a hint, put "AFCI protected" both above and below the sockets.
  • 2 Common trip? Not required. That would differ from #3 if the installation method was fuses and a shutoff switch.
  • 3 Common maintenance shutoff? @EdBeal points out "YES" because they are on a common yoke, based on 210.7 in 2014 and 2017 Codes.
  • 4 On the same leg, I would call marginally better, but it contradicts #3 so it's not gonna happen.
  • 5 Risk of 240V arcing? In any case your AFCIs will snuff that right out.
  • 6 I can't think of anything.
  • 7 Worrying about the hots touching, you are stuck with it because of #3.
  • 8 Nothing special about separating receptacles, they are meant to be able to be independent.
  • I'd love to use 12/2/2, but it's 4 times the price of 12/2. So it' much cheaper to pull two 12/2 runs. I've also updated the question with some of the things I thought might be an issue, like labeling requirements. – Nick Oct 5 '17 at 20:05
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    210.7 requires simultaneously disconnect of ungrounded at source if on same yoke both in 14 & 17 code – Ed Beal Oct 5 '17 at 20:53
  • @EdBeal I don't have those codes handy but they make sense. – Harper Oct 5 '17 at 21:01
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    Wouldn't #3 and #4/#7 be mutually exclusive? ie. You can't have them on the same leg and have a common maintenance shut off, since any two adjacent breakers would be opposite legs, right? Or in other words, requiring a common shutoff would force you to use opposite legs? – Nick Oct 5 '17 at 23:34
  • @Nick that's a very good point. So clearly the Code authors have thought this through, and intend it. – Harper Oct 6 '17 at 1:22

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