code-complianceelectricalkitchens
I'm in California.
Current code, AFAICT, requires a dedicated circuit for dishwasher. That means that, by default, the disposal (being under sink) would also have its own circuit.
In my kitchen renovation we're intending on two disposals. One in a primary sink and another in a prep sink. They will be on different receptacles, on opposite sides of the room.
Can these two disposals share a single 20A circuit or must each disposal have a dedicated circuit?
No, Code says nowhere that a receptacle-type AFCI or GFCI is required; breaker-type GFCIs and AFCIs are also usable whenever AFCI or GFCI protection is called for by the NEC or otherwise desirable. In fact, circuit breaker manufacturers now offer a device that's both a GFCI and a CAFCI in the same package -- look for a DFCI (Dual-Function Circuit Interruptor) breaker.
As to your clarified question (cites from the 2014 NEC):
The refrigerator receptacle and the dedicated microwave receptacle do not require GFCI protection, as those receptacles are not installed to serve the kitchen countertop surfaces, and likely are more than 6' from the edge of your kitchen sink as well.
The DW circuit, however, does require a GFCI, even though it is hardwired, as per 210.8(D):
(D) Kitchen Dishwasher Branch Circuit. GFCI protection shall be provided for outlets that supply dishwashers installed in dwelling unit locations.
Note the word "outlets" in this passage, vs. the use of the term "receptacles" in 210.8(A) -- in Code parlance, an "outlet" is a place where power is tapped from a circuit to serve a utilization device, whether it be a hardwired device, a luminaire, or a cord-and-plug connected device, while a "receptacle" is what you plug cords into.
The disposal does not require GFCI protection either, unless its receptacle is within six feet of the top inside edge of the sink bowl "as the cord flies". (In other words, the receptacle, while not covered by 210.8(A) point 6, may fall under 210.8(A) point 7.)
Yes, you are right. Current code wants the dishwasher GFCI protected. However, unlike the dishwasher, there is no specific article that explicitly states a disposal requires one.
A Double pole GFCI 20 Amp breaker can protect two individual appliances. The Wiring is known as a MWBC "multi-wire branch circuit" and uses 12-3 "Black, Red, White, and Ground".
However, current code also wants everything in a kitchen, including dishwashers to be ARC-fault protected. One solution is to use a Double-Pole Dual GFCI/ARC fault 20 Amp breaker.
But since you ran two separate branch circuits I don't think code allows you to combine the neutrals as one in the panel because the conductors are not in the same sheath/raceway when they leave the panel. In which case, you would just do as you mentioned using a 2-gang box with one GFCI and one regular outlet, which is probably far way less expensive!
Best Answer
Which code are you referring to? I am not aware of any requirement in the NEC that requires a dishwasher or a disposal to be on a separate circuit. However it is considered good practice.
Since you are asking about two disposals, we are talking about two motor loads. 2017 NEC Article 220.18 (A) Motor Operated and Combination Loads, states that the calculated load of motors or loads, shall be 125% of the largest motor and the sum of all the other motors and loads. HP to Amperage conversion can be found in NEC Table NEC 430.248.
For example if you are installing 2 disposals that are both 1/2 HP the required amperage would be 9.8 amps, 9.8+9.8+(25%*9.8)= 22 amps. So that would be too large for a 20A circuit. If the disposals where 1/3 HP it would change to 7.2+7.2+(25%*7.2)= 16.2 amps, which would fit on a 20A circuit.
This example shows that it would not be wise to put any disposals on the same circuit. Since even though you might install 2 1/3 HP disposals or less, someone in the future could change them out to larger HP later and overload the circuit.
Remember I said it was good electrical practice. A good electrician will always size a circuit to handle all future loads, not just the ones present at the time.
Good luck with your project.