GFCI Receptacle Installation

[Don_M]

I’m thinking a schematic might help. Based on what I am hearing – does the below sketch represent your situation?




It looks like there are no other wires into/out of the GFCI box. If so, then is this the last receptacle in this circuit? Are there any other receptacles upstream of the GFCI/dishwasher boxes that are part of this circuit and that are/should be GFCI protected?




In any event, if the schematic is accurate, then simply “capping” the red wire in the GFCI box will probably not work – or better said will not function effectively/efficiently because the GFCI receptacle and the dishwasher would then share a common neutral which could  result in a current imbalance and trip the GFCI intermittently. The GFCI compares the current flowing out (hot side) with the return  current flowing in (neutral side). It only takes about a 5 Ma difference to trip the GFCI (that is not much!) and an additional appliance sharing the neutral creates this imbalance.




Also, per code, you are required to have two dedicated 20 A “small kitchen appliance” circuits. The existing configuration doesn’t quite get you that (since the dishwasher is also on this circuit). So, unless you want to run a bunch of new wire,  I think a DP GFCI breaker is the cleanest way to go. With a DP breaker you can the cap the red wire (only use the black on the GFCI) and the red will provide GFCI protection to the dishwasher – not really needed, but probably won’t hurt.




You could use a GFCI receptacle as you originally planned, but you would need to wire the dishwasher in parallel with the GFCI by using the red wire on the load side of the GFCI to run the dishwasher (and again this would also provide GFCI protection to the dishwasher)




(FYI - when I refer to a 3 conductor cable  (ii.e., 12/3 or 14/3 Romex)- that implies 2 hots (red and black) and 1 neutral. The ground wire isn't typically counted as a conductor)



Existing Wiring??

   


DP GFCI Breaker

   

[Willyou]

I think, based on the information you are able to give us, there is not enough certainty to be able to give you a good answer. I advise you to get an electrician to figure it out. The risks are too great not to.

[BaileyNo5]

You guys are great.  Don, thank you for the schematic, that is exactly the situation.  And I think I have figured out the WHY.

All of my kitchen outlets are wired this way, with 2 hot wires going to them, so each plug-in has it's own power source.  One of them is also tied to the dishwasher.  All the others appear to be independent.  My best guess is this was done to prevent tripping a breaker in the event multiple appliances were plugged in at the same time.  This is an OK way to wire an outlet - if it's not near a kitchen sink.  Because as we all know now, this isn't friendly to GFCI receptacles.

In the attached picture, I have capped the red (hot) wire, and attached the black (hot) and white (neutral) to the LINE connections on the GFCI outlet.  Dishwasher still runs fine, and the GFCI outlet tests good.  Capped red hot wire was wrapped securely in electrical tape before stuffing it in the back of the box.

I am declaring this a big win, because I have avoided paying for 2 expensive double pole GFCI breakers, my outlets work, and I think it is safe.

You are all invited over for Easter dinner.  With 4 receptacles in the kitchen, I can run up to 6+ major appliances at once - blenders, air fryers, toasters, rice cookers, electric fryers, you name it.  We got the power! 

[BaileyNo5]

It looks like there are no other wires into/out of the GFCI box. If so, then is this the last receptacle in this circuit? Are there any other receptacles upstream of the GFCI/dishwasher boxes that are part of this circuit and that are/should be GFCI protected?
> Yes, this is the last receptacle in the circuit.

In any event, if the schematic is accurate, then simply “capping” the red wire in the GFCI box will probably not work – or better said will not function effectively/efficiently because the GFCI receptacle and the dishwasher would then share a common neutral which could  result in a current imbalance and trip the GFCI intermittently. The GFCI compares the current flowing out (hot side) with the return  current flowing in (neutral side). It only takes about a 5 Ma difference to trip the GFCI (that is not much!) and an additional appliance sharing the neutral creates this imbalance.
> Hmmm.....this might be a problem.  I'll run the dishwasher and an appliance plugged in to the receptacle and see if anything happens.  After the test, I may end up going with one 2-pole GFCI breaker.  We'll see.

Do me a favor – run the dishwasher and then run an small appliance on the GFCI receptacle and see if it trips

EDIT: @Don_M: OK, I ran the dishwasher and then plugged an air fryer into the outlet. Both ran for about 10 minutes without tripping the breaker or the GFCI. Seems like it might be OK. We'll keep an eye on it over the next week or so. If there are any problems, I can probably pull the dishwasher out and snake wire between the dishwasher and the GFCI outlet. I'll keep you posted.

[Don_M]

No desire to rain on your parade (or victory dance, as the case may be!), but I think you may have intermittent nuisance tripping issues with just capping the red wire as you have shown. If the schematic is correct, then the dishwasher AND the GFCI receptacle share the same neutral and the current which the GFCI “monitors” may become imbalanced when running the dishwasher AND using the GCFI receptacle  to, say, power a small appliance. IMO - not the best way to wire this circuit (likely doesn’t meet code).

Do me a favor – run the dishwasher and then run an small appliance on the GFCI receptacle and see if it trips. If it does trip, then below is a potential alternate way to wire. Two questions: (1) can you access the JB where the dishwasher is hard wired, and (2) can you pull a small 2 conductor Romex between the GFCI box and the dishwasher box?

If so, then you can have the dishwasher feed off the GFCI as a downstream load* and protect the dishwasher thru the GFCI*. Under this configuration, you would not really need the DP breaker since the red wire is superfluous.

*FWIW – I believe new code requirement is for dishwashers to be independently GFCI protected, and so this is not exactly that, but you may be grandfathered in under your current set-up

   

[Roly]

No desire to rain on your parade (or victory dance, as the case may be!), but I think you may have intermittent nuisance tripping issues with just capping the red wire as you have shown. If the schematic is correct, then the dishwasher AND the GFCI receptacle share the same neutral and the current which the GFCI “monitors” may become imbalanced when running the dishwasher AND using the GCFI receptacle  to, say, power a small appliance. IMO - not the best way to wire this circuit (likely doesn’t meet code).

Do me a favor – run the dishwasher and then run an small appliance on the GFCI receptacle and see if it trips. If it does trip, then below is a potential alternate way to wire. Two questions: (1) can you access the JB where the dishwasher is hard wired, and (2) can you pull a small 2 conductor Romex between the GFCI box and the dishwasher box?

If so, then you can have the dishwasher feed off the GFCI as a downstream load* and protect the dishwasher thru the GFCI*. Under this configuration, you would not really need the DP breaker since the red wire is superfluous.

*FWIW – I believe new code requirement is for dishwashers to be independently GFCI protected, and so this is not exactly that, but you may be grandfathered in under your current set-up

Don try redrawing the schematic where the power from the breakers goes to the junction box first.   Then the dishwasher neutral is not going thru the gfci. 
Cant tell which hot is connected to the dishwasher but if you have trouble with the breaker tripping then remove and cap the black wire on the gfci and connect the red to the gfci.   Since you tested it it should be ok.    Older codes did not require the dishwasher be ground fault protected if they were hard wired as this is.   Roly

[BaileyNo5]

Don try redrawing the schematic where the power from the breakers goes to the junction box first.   Then the dishwasher neutral is not going thru the gfci. 
Cant tell which hot is connected to the dishwasher but if you have trouble with the breaker tripping then remove and cap the black wire on the gfci and connect the red to the gfci.   Since you tested it it should be ok.    Older codes did not require the dishwasher be ground fault protected if they were hard wired as this is.   Roly

Hey Roly thanks for your contributions and help.  So far it looks like capping the red wire is going to work.

[BaileyNo5]

The outlet on the other side of the sink was wired the same, and I used the same approach - capped the red wire and tied the black and white into the LINE on the GFCI. As far as I can tell nothing else is wired into this circuit, it only has one outlet on it. Outlet works fine, GFCI tests good.