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I have a multi wire branch circuit using two 20amp breakers and a single run of 12/3 wire to a single split outlet in our laundry room. The top outlet (black) powers the gas dryer, the bottom outlet (red) powers the washer. We are adding a wet bar to the opposite side of the laundry room wall. I would like to run power from that laundry outlet to a new GFCI breaker outlet (because it will be within 3 feet of a sink), and then on to another outlet that will power beverage fridges. Can I pigtail connections to one of the outlets in the laundry room receptacle in order to provide this new power? Will the GFCI work correctly for itself and the new outlet downstream of it? Or will the shared neutral and ground screw up my plan?

Proposed Wiring Diagram

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  • So if i'm understanding you guys correctly the laundry outlet that currently exists in our house (California, built in the 90s) is no longer up to code? There is no handle tie on the breakers which is why it took me awhile to even determine it was two separate breakers for one receptacle. We added a GFCI to the washing machine plug, one of those self contained add ons. Vaulted ceilings and 100+ weather is going to delay running new wire. What a bummer. Here I thought I found an overpowered circuit that would be easy to tap into.
    – SJacobson
    Aug 16, 2020 at 21:13

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The fact that it is a multiwire branch circuit may have been allowed in the past I don’t remember but think it may have been ok. Today the laundry branch circuit is a required circuit and it is a dedicated circuit and can have no other receptacles so it would not be code compliant by today’s code or many code revisions back to add the GFCI receptacle even if properly wired.

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    OP has a dedicated laundry circuit, the red half-circuit. Nothing says other circuits can’t also have outlets in the laundry room... does it?
    – Harper - Reinstate Monica
    Aug 16, 2020 at 0:59
  • At Harper Go ahead put that as an answer As a professional electrician I would not try to sneak that by today’s code that would not fly in my jurisdiction as a dedicated circuit as it shares a neutral that is not dedicated. I have run into this into this with sump pumps where the inspector would not allow a multiwire because the pump was required a dedicated circuit in that case.
    – Ed Beal
    Aug 16, 2020 at 1:17
  • Well, that is a good point...
    – Harper - Reinstate Monica
    Aug 16, 2020 at 3:08
  • @EdBeal -- 210.4(A) states that "Branch circuits recognized by this article shall be permitted as multiwire circuits. A multiwire circuit shall be permitted to be considered as multiple circuits." So, I suspect that the Code intent is closer to what Harper is saying than what you've run into with your inspectors, although I don't have a Handbook handy to confirm that
    – ThreePhaseEel
    Aug 16, 2020 at 6:10
  • An inspector told me that because they share a neutral that is not dedicated. I have a hand book and have re read the section including commentary. Dedicated circuits are not addressed. Since I have been called on this as I said and it was on a permitted job (thus the inspection) I would not try it again. Other inspectors may not even notice or agree. This was a real life situation not I think the code states. Depending on the number of inspections on the permit a flag or failure may even cost 50$ + or whatever the local fees are and a delay in finishing 1 extra run of wire becomes cheaper.
    – Ed Beal
    Aug 16, 2020 at 14:45
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First, the two breakers need a handle-tie. Or replace them with a 2-pole breaker.

When you splice or extend neutral on a MWBC, you must pigtail the neutral. You cannot use a device such as a recep to splice.

Other than that, I do not see a problem, except... ok. Bear with me. Modern Code requires the laundry room have a dedicated circuit all its own. It doesn’t say two, just one. If you are grandfathered, you don’t need to update to new Code, but you’re still not allowed to make things worse.

But my interpretation of that is that you have a dedicated circuit, the red. Extending the black to a mini bar is fine.

Now Ed Beal has concerns that a lot of inspectors will not like a multi-wire branch circuit serving half a dedicated application. So it'd be worth talking to your AHJ about that.

But here's an idea: what is a general safety problem is a lack of GFCI in the laundry room. So I would kill two birds with one stone and replace the laundry recep with a GFCI recep on the red circuit only. Both problems solved!

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  • Not sure how putting a GFCI in would solve a shared neutral the sump circuit I mentioned was in a unfinished basement and the other half was to be for receptacles that were GFCI protected that was a no go for that inspector. This guy knew me and explained it the same as I did that sump pump was required to be a dedicated circuit sharing the neutral was not dedicated. Some inspectors may not catch this and grandfathering really can be an issue with updates.
    – Ed Beal
    Aug 16, 2020 at 4:04

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