Correcting GFCI for dishwasher and disposal

Question

See image for my proposed solution. I'd like to know if this is considered correct.

My house is 84 years old and I am certainly inheriting many sins so please keep that in mind. While I may not be able to reach today's code with the constraints I have, anything will be better than how it was before this.

I am having to replace my dishwasher, and what I found was a single circuit with a single GFCI outlet above counter which was improperly wired, meaning all the connections were made to the line side of the GFCI, and nothing was connected to the load side. From the line side of the GFCI, one connection went through a switch which was hardwired to the disposal, and a separate hardwire went to the dishwasher. Probably been this way for 10-15 years I'm guessing.

I'd like to get to a GCFI protected half-hot outlet under the sink and eliminate the hardwires for the disposal and dishwasher. Circuit is currently all 12-2 and a 20A breaker.

NOTE: Grounding conductor not drawn, just to keep the diagram readable

Answer 1

Your plan generally looks good. A few things to consider:

• Deadfront vs. Receptacle

While strictly speaking you may be able to use a GFCI/receptacle, I don't recommend it. Why? Overload possibility. With a GFCI/receptacle, someone could plug in a toaster oven or other high-current appliance while the dishwasher is running and trip the breaker. Assuming this circuit is separate from the minimum two countertop receptacle circuits, make it a circuit only for the dishwasher and disposal and you avoid the possible problem. A deadfront GFCI installs exactly the same as a GFCI/receptacle, it just has no place to plug anything into it.

• Hardwired vs. Receptacle Dishwasher and Disposal

Personally, I am a fan of hardwired appliances. The only catch is that code now requires either a visible disconnect or a lockout mechanism for service. Unplugging an appliance is a very easy disconnect. However, I am pretty sure that a deadfront GFCI that is switch-rated (i.e., instead of, or in addition to, TEST/RESET, it is also labeled ON/OFF) will also work as a visible disconnect provide it is within sight of the protected equipment. So the deadfront GFCI ends up allowing hardwiring of the dishwasher and disposal.

• Total Power Requirement

You should make sure that the dishwasher and disposal together do not require more than 20A. While it is unlikely that this will cause frequent nuisance trips, it is a consideration and you really don't want to overload the circuit unnecessarily. A typical disposal such as an Insinkerator Badger 5 1/2 horsepower has a rating of 6.9A. I checked a few dishwashers (Frigidaire, Whirlpool, Kitchenaid, GE) and they range from 7A to 15A. Most only hit their top rated power usage when heating (either heating water or drying), so most will be OK with a disposal on a 20A circuit.