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Wiring an outlet for a dishwasher and garbage disposal meeting current 2017 NEC.

I have a 1940’s Cape Cod house, and am working on updating my kitchen.  Currently the kitchen has a garbage disposal, and no dishwasher.  I am going to be installing a dishwasher, and want to have it plug into the same receptical under the sink, which I understand is most commonly done.  The current wiring going to the disposal is old, and will be re-wired when I install the dishwasher.  I also want to make sure it meets the current 2017 NEC.


  I have been doing research, but I can not get a definite answer.  Here is my understanding.  If anything is wrong, please correct me.


- The garbage disposal and dishwasher each require 12/2 wire.  To run wire from the panel to the outlet, I can use 12/3 wire.

- A 20A, 120V, 2 pole circuit breaker should be used, one breaker for the dishwasher and one for the disposal.  2 pole, so if a repair is needed at the outlet, both circuits are turned off, for safety.

- One split-tab receptical is placed under the sink.  This receptical should have the tab broken on the hot side, and the tab should stay connected on the neutral side.  

- One single pole switch, for the disposal.  12/2 wire can be ran from the switch to the receptical.



Here is my confusion.  


I have read that all Kitchen recepticals are required to be AFCI protected.  Also, that all recepticals within 6 feet of the kitchen sink needs to be GFCI protected.


Where do you place the AFCI and GFCI?  My understanding is that both are required.  I also understand that you can install them at either the breaker or the receptacle.  Do you install the AFCI at the circuit breaker, and the GFCI at the receptacle?  Or, I have read that there are circuit breakers that do both AFCI and GFCI, although, I have not found one that does 2 poles.  I’m a little lost as to where these fit into the complete circuit to meet the current codes.


Please help me understand what I am missing.  I believe I understand how to wire each item together, but it would not hurt to double check that as well especially since it may change with where the GFCI and AFCI would go if they are required.




Re: Wiring an outlet for a dishwasher and garbage disposal...


You MUST have a seperate circuit for each device(appliance). You are not allowed to share a neutral for anything in a kitchen. You Must have two single pole breakers. You will also thank yourself in the long run. I also suggest intalling a single pole switch before the outlet just so that you would not have to go back to the breaker panel just to turn off that particular circuit.

AFCI/GFCI are combined in either the breaker or the device. It would not make logical sense to have an AFCI breaker and then a GFCI device. That would quickly become a maintenance nightmare. I like, and suggest using the breaker and not the device.

I have used all AFCI/GFCI breakers in my home. That way even the wire between the breaker and the first outlet is also protected. Where as if you use an AFCI/GFCI device, only the device and the wiring from that device to the next is protected.


Handy Andy In Mt Airy NC

Re: Wiring an outlet for a dishwasher and garbage disposal...


So, buy two - 20A, 120V GFCI/AFCI breakers, and break both tabs on the split tab receptical under the sink.  Run two separate 12/2 wires from the service panel to the receptacle, and connect one of the two outlets to a single pole switch for turning on/off the disposal.  Does that sound correct?

Re: Wiring an outlet for a dishwasher and garbage disposal...


I would never split a outlet like that. What happens when you need to work on one appliance, but not the other? You would have to turn both off, or take a risk of being shocked by keeping one on. Use AFCI/GFCI breakers, run the wire thru a single pole switch for ease of turning off the power to each appliance if needed, and then on to the outlet. One box and one outlet per circuit. Never cross or combine the circuits. The switches under the sink have nothing to do with turning either appliance on or off for use. They are there to turn off the power to the appliance if needed.

That is what I would do, and have done mine. I used a pilot light switch so that I would know for certain if the power is on, or off. I also used an air operated switch for the disposer. Never a good idea to mix water and an electric device. Even though they are safe enough, that is one more item between that keeps the human from touching a device that is direct connected to electric. I use all water tight conduit, boxes and fittings under the sink.


Breaker -----> Disconnect Switch ------> Power Switch for Disposer Operation -----> Outlet


Breaker ------> Disconnect Switch ------> Outlet

For even more conveinence under the sink, I installed a set if leds in rope format, I placed them inside of clear rubber tubing so they would not be damaged. I used a magnetic switch on the doors, so that when either/both doors are opened, the lights would come on. It makes it nice to work under the sink. I installed the lights first, before working on any thing else.


Handy Andy In Mt Airy

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