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In addition to my 2 dedicated small appliance circuits on the main counter, my kitchen has an island with sink and dishwasher. I have two dedicated circuits available for the island and need to wire the dishwasher, the disposal, and the outlets on either end of the island.

What is the approved way to wire all three of these with two dedicated circuits? My instinct tells me disposal and one outlet on one circuit. Dishwasher and other outlet on remaining. Both are 20A and both will be gfci. Location is Ca.

Thanks!

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    How much current do the dishwasher and disposal pull? – ThreePhaseEel Jan 13 '18 at 0:48
  • You said your Island has these items already - why do you need to rewire it ? Are you adding something here ? – Ken Jan 13 '18 at 3:16
  • The kitchen is a renovation. Completely new layout. I will check on what they pull. – Tammy whynot Jan 13 '18 at 5:35
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    Dishwasher is 10.6A and the disposal is 6.3A. – Tammy whynot Jan 13 '18 at 5:38
  • They are fixed appliances. Best to have them seperate from the outlets – Ryan Walkowski Jan 13 '18 at 18:31
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The first rule is that you can't have any receptacles on a circuit if the fixed load is more than 50% of circuit capacity. So on a 20A circuit, that means 10A. Your 10.6A dishwasher cannot be on the same circuit with any receptacles.

The second rule is that if an appliance is able/likely to run continuously for >3 hours, you must plan for 125% of its capacity on the circuit. I'm not sure if a dishwasher qualifies, but if so, it counts as 125% of 10.6A or 13.25 amps. The disposal is definitely not a continuous load, so it counts at 100%, or 6.3 amps. Together, they count as 19.55 amps, which nicely fits a 20A circuit.

This design seems to "write itself": the dishwasher circuit can't have receptacles, leaving it with a bunch of spare capacity nothing can use except the disposal.

That would leave the other circuit wide-open for receptacles only.

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Over time wiring methods have changed because of a greater demand for power in many of our appliances. In the beginning no one had problem with connecting a disposal and a dishwasher on the same circuit. We would put in a split duplex receptacle then switch one to the disposal and keep one hot for the dishwasher. Now most contractors will put each appliance on a separate circuit.

So from a logical standpoint I would put the dishwasher on one circuit. Then I would install the disposal and other receptacles on the other. There is no rule saying a disposal can't be on a small appliance circuit and there is no rule that says you can only have two small appliance circuits in the kitchen. Finally, how many times would you be running a high power usage appliance and the disposal at the same time.

PS The NEC has always struggled in dealing with residential kitchens. Especially about small appliance circuits and fixed appliance circuits. Even the 2017 NEC has made changes defining and redefining these sections. Right now there is a debate about GFCI protection and penetrating partitions. Meaning there are a lot of different opinions on this subject.

Hope this helps and good luck.

  • It does help. Thank you. It makes sense to me as you are correct, the disposal and the outlets are not likely to be run at the same time. What I don’t understand is how splitting a duplex receptacle into two plugs mitigates the load on the circuit. Or are you talking about running one circuit to one plug in a duplex and the other plug from a separate circuit? If that is the case runn8ng each circuit to its own duplex seems less complicated. – Tammy whynot Jan 13 '18 at 15:50

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