I've seen a few similar questions but each has a small difference that makes the answers there irrelevant for me.


I just finished a kitchen remodel, including redoing much of the kitchen electrical work. An electrician did most of the wiring in the walls but I'm finishing the "trim work" (receptacles, switches etc..). I'm trying to verify that I have things wired correctly before I request inspection (in WA state, following 2020 NEC).

What I have


  • A MWBC, with a 15A two-pole breaker, covering the two circuits for my dishwasher and garbage disposal (respectively). The breaker is a plain one with no AFCI or GFCI.
  • A "plain" (not GFCI/AFCI/etc..) duplex receptacle under the kitchen sink, wired as a split-tab receptacle (metal tab broken off to separate the dishwasher and disposal circuits).
  • An extra 14/2 cable connecting the "hot" wire of the disposal circuit to a switch next to the kitchen sink.


  • Dishwasher and disposal are both connected via a power cable (i.e. not hard-wired).
  • The manuals for both appliances say nothing about GFCI or AFCI. They just say to do whatever the local regulations require.


As I understand it:

  • New dishwasher outlets need to be both GFCI and AFCI protected.
  • New disposal outlets need to be AFCI protected (GFCI is optional here).

Right now neither circuit has GFCI or AFCI.

The simplest solution for me would have been to grab a "Dual Function" breaker like this one instead of my current two-pole breaker. Unfortunately, I don't think Square D Homeline makes any two-pole 15A "Dual Function" breakers.

For $120-200 I can get either GFCI or AFCI at the breaker, but that leaves me without the other. And I don't think I can use a GFCI receptacle either since I need to wire it as a split-tab receptacle.

Additional details

  • The wiring for this circuit wasn't touched as part of my remodel, aside from just replacing the plain receptacle with a newer white one. All the wiring in the wall and panel should be the same as it was before. But all the other circuits in the kitchen were replaced.
  • The house was originally built in 1993, so whatever code was in place at the time applied.
  • I have a 200A Square D Homeline 40/80 space/circuit panel.
  • I believe WA state is on 2020 NEC, and I can't find any specific local laws that overrule these parts.
  • I've called my inspection office and they told me to just read the laws online.

My questions

  1. Do I even need to bring these circuits into compliance, given that they were like this before and the wiring in the wall and panel hasn't changed?
  2. If yes, what are my options here? I'm willing to consider different options at either end, but I don't want to do anything in the wall or run a different circuit since we've already closed up everything.
  • 1
    If you're going to eliminate the logical option of putting in an extra box to put the kitchen end protection in, have fun with that. Cheapest way to do the job.
    – Ecnerwal
    Apr 10, 2023 at 23:00
  • 2
    Just replacing the receptacle, that circuit should be grandfather in. Question will be what the code said when that circuit was placed if it is in code. Adding GFCI would be a good idea.
    – crip659
    Apr 10, 2023 at 23:01
  • 1
    @Ecnerwal are you proposing replacing the 1-gang box with a 2-gang old-work box that has two separate receptacles, then doing the AF/GF at the receptacle? if so that's an interesting option and might be simple enough.
    – peter
    Apr 10, 2023 at 23:23
  • Another option just came to mind: if there's no requirement for dedicated DW and diposal circuits, can I just cap out the red wire in both the panel and the electric box, and use a 1-pole CACFI breaker for this circuit?
    – peter
    Apr 10, 2023 at 23:24
  • If the remodel is significant and you did a lot of new wiring, and especially if you damaged significant portions of the kitchen walls and are going to completely tile/paint the new room, I doubt an inspector would let you grandfather one lonely outlet. And especially not one that heavily involves metal appliances and water. You should WANT to go above and beyond for this one.
    – jay613
    Apr 11, 2023 at 14:39

1 Answer 1


If you replace the 1-gang box with a 2gang (or 4 inch or 4-11/16 inch with appropriate 2-gang faceplate), you can do AFCI at the breaker and GFCI at the receptacle by splitting the MWBC into two GFCI receptacles in that box.

The other direction (GFCI at breaker and AFCI at receptacle) isn't to code unless the wiring method is in metal the whole way to the receptacle, which is unlikely in most jurisdictions that are not very fire paranoid.

It's very likely that you need the MWBC because it's very likely that one or both of the appliances are over half of 15A (i.e. >7.5A) and when that happens, you're supposed to dedicate the circuit to the appliance that draws more than half the breaker value, IIRC.

You might be technically correct that this untouched circuit does not need to be upgraded, but that risks a potential disagreement with the inspector on the one hand, and possible issues that the modern code requirements are there to prevent, on the other.

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