ECN Forum Forums Code Related Discussion NEC & other Code issues Dishwasher/Disposal

And that all makes sense to me too because when I think Dishwasher and Garbage Disposal I think appliance, not motor. Makes for a good discussion though, doesn't it? It's good to know though that in a pinch (1) 20 AMP circuit is good for both appliances and Code compliant. At least as far as I can see.

For what it's worth,

I have done a few dozen homes with Disposal & GD on a single 20-amp ckt. Never had a call back.

However, I do run a 12/3 MW ckt to a laundry room if the dryer is gas-operated.
I believe that the possibility exists that a load of wet clothes in the dryer and a load of wet clothes on the spin cycle of the washer may trip a single 20-amp ckt if the motors start simultaneously.

Absent any nameplate data, I think it is a safe bet.

8.7 and 6.7 = 15.4 amps. You are also able to round down to 15 amps. the .4 can be rounded down to 15 amps. Check the code book but for whats its worth your good to go.

Coupla things:
If you guys are using 430 for your calculations then it's 1.25 x 8.7 plus 6.7 and your looking at 17.8 as your load. Another thing is we do need to look at the manufacturer's specs and make sure that they don't ask for a dedicated 15 ampere circuit for the appliance. I'm been on both sides of that argument.

George, in the dishwasher, I doubt that the motor is the big load, it will be the heater so you will be doing 1.25% of the disposal, plus the motor load of the WD or the resistive load since they are usually non-coincident. I bet you will be using the resistive load since it is probably larger.
That is a whole lot of calculating, based on an appliance that may not even be ordered when they do the rough and long after the plan review.

This thread is NEC and other codes so let me offer a CEC solution .
Section 28 sizes multiple motor circuits as 1.25 time the largest motor plus the sum of the currents of other motors that would run at the same time or 17.575 amps. For motors this is fine on #12 but the breaker could be undersized if both motors start at the same time. Not a violation here.

The NEC rules are the same on this.


1.25 time the largest motor plus the sum of the currents of other motors that would run at the same time

But as Greg pointed out that Motor in the DW is not 8.7 amps it will be much less than that. Much of that 8.7 amps will be the heater.

Don't think this one needs to go past 210.23 (A)(2)... Over 50% you'll need another circuit.

The problem with 210.23(A)(2) is niether one of these are 10a

Exactly.... Neither is over 50%, or a continuous load. If one were 10.1A, and the other say 3A... It would need a seperate circuit.

But I would normaly make it two anyway - out of force of habit, and general standard.