Disposal Circuit Update

Question

I moved to a house built in 1995 and want to update the disposal connection, but found some conflicting rules that I don't know how best to comply with.

The existing connection is a 14-2 NM cable run through the middle of the sink cabinet. Many years of the faucet sprayer hose rubbing against the cable is evident.

If I could bring that cable back to a surface-mount receptacle on the back of the cabinet, that would seem more safe. I realize the latest NEC requires new kitchen receptacles to have AFCI protection. So I checked inside the panelboard. I found the disposal is part of a MWBC with the dishwasher.

According to Siemens, their single pole AFCI breakers are not appropriate for a MWBC. I could buy the 2-pole AFCI breaker, but this raises many more questions.

The latest NEC also requires GFCI for dishwashers, and I'm concerned I would be breaking rules by doing anything to the original dishwasher circuit breaker. There doesn't seem to be a 2-pole dual function circuit breaker available for this situation.

It looks like there are rules preventing me from using an AFCI type receptacle, because the disposal is switched and not on a continuous run.

Is there a simple way to add this disposal receptacle in compliance with 2020 NEC?

Edit: I've learned the disposal switch box is the first box on the MWBC, has 2 switches and 4 other cables connected. Adding a blank face GFCI for the dishwasher and a duplex switch is possible, but is it required?

Answer 1

I'd just go with the blank face GFCI + duplex switch approach

The simplest and cheapest way to handle this for the foreseeable future would be to put a 2-pole AFCI breaker in at the panel, then rearrange the disposal switch box to use a duplex switch (2 switches on the same yoke) beside a deadfront (sometimes called blank face) GFCI for the dishwasher. This puts the dishwasher GFCI in a convenient place if it ever trips, and works around the issue with the lack of 2-pole DFCI breakers without requiring the replacement of the homerun cable.

Answer 2

The work that you are not disturbing should be grandfathered.

That means it only needs to meet Code for the day the permit was issued.

Since AFCI is primarily to protect the wiring in the walls, I don't see a point to an AFCI receptacle. Though, it would protect a flexible cable that is being chafed.

Answer 3

It looks like the NEC never anticipated unavailability of dual function circuit breakers for MWBCs.

While 406.4(D)(3) addresses replacement of receptacles requiring GFCI, there is no mention of updating hardwired appliances or of replacement of circuit breakers.

I think this means it's simply not feasible to add GFCI protection in this situation without modifying the dishwasher circuit. So replacing the old circuit breakers with a 2-pole AFCI seems reasonable.