Kitchen Remodel Electrical Question:

[oldberkeley]

I'd like to have the garbage disposal and the dishwasher plug in to a receptacle under the sink.

The garbage disposal would be switched (next to the sink) and the dishwasher would be on a GFCI (which I think is now code.)

Can these two appliances share one dedicated 20 amp circuit? If so, how would I wire it?

If not, what would be the correct way to wire this setup?

TIA.

-Gary

 

[LXCam]

Yes as long as you connected load is under 18 amps. Where you'll run into an issue is you will need to install a GFI breaker, then you can install a 20 amp receptacle and break the tie tab between top and bottom (top or bottom constant hot, the other switched). Also I hope your dishwasher is right next to the sink or the cord may not reach. Granted all though I've been in the trade for better then 30 yrs, I'm not a resi guy so there is always a chance there has been a code change that could impact that suggestion.

 

[oldberkeley]

LX- Thanks much for the quick reply.

I understand. I'd have to install a new 20 amp breaker anyway, the GFCI breaker is of course more expensive but that's OK.

Yes, the dishwasher is right next to the sink.

Also, I'm going to assume by your answer that it is impossible to split a GFCI outlet (half hot, half switched)?

-Gary

 

[justsam]

An alternative that may work for you is to use a pneumatic button switch for the disposal. It plugs into an "always hot' outlet, but requires that your sink has the punch out for it.

Regardless I would use a GFI breaker just so I did not need to crawl under the sink, move cleaning supplies etc. to reset a tripped GFI.

You may want to plan ahead and confirm the approval authority is OK with them being on the same circuit.

 

[PT Doc]

An alternative that may work for you is to use a pneumatic button switch for the disposal. It plugs into an "always hot' outlet, but requires that your sink has the punch out for it.

Regardless I would use a GFI breaker just so I did not need to crawl under the sink, move cleaning supplies etc. to reset a tripped GFI.

You may want to plan ahead and confirm the approval authority is OK with them being on the same circuit.

We have the pneumatic switch and I wouldn't ever use a switch. They are either on the side of the island or under the sink. Very inconvenient.

 

[LXCam]

Ob, right you can't split a gfi recep.

 

[Mustang51js]

You don't need it on a gfi, unless your state adopted the 2014 code already. You do need a single receptacle under the sink or a breaker lock on the breaker if it's hard wires or outlet is inaccessible. They are supposed to be on separate circuits but you can get away with it by not using both at same time

 

[zmaxmotorsports]

Just install a 2 gang box under the sink and run the 20a circuit to the line side of gfi to feed dishwasher.
Then come off of the load side of the gfi to feed a switch leg above cabinet ,then drop it back into the 2g box to feed a duplex recept which will be gfi protected to feed disposal.

 

[James-W]

My opinion is to run a separate circuit for the dishwasher and hard wire it. The cost to run the additional circuit would be relatively minimal and it is just a better way to do it.

 

[volleyball]

I agree with with the dishwasher plugged into the gfci then the load wires from the gfci to the switch and then to the disposer. You won't overload the 20a and even if you got some super binford disposer, you just wouldn't run it while the dishwasher is going.

 

[alfredeneuman]

As an alternative to the GFI breaker, you could put a faceless GFI next to the garbage disposal switch. You'd just have to use a 2 gang box.

It would be both more convenient than the breaker, and less expensive.

EDIT: I believe Ohio is still on the 2011 NEC, in which case GFI on a GD isn't required.
I don't have a copy of the 2014 NEC.

 

[wyliesdiesels]

Ummmm, IM surprised no one has mentioned this yet. why not install a MWBC(multiwire branch circuit)? Many homes use a MWBC for the dishwasher and disposal!

 

[sberry]

A disposal is rather small, I really doubt it would be an issue.

 

[James-W]

I have always felt it is best to have certain appliances on their own circuit. Appliances like freezers, refrigerators, and to a lesser extent, dishwashers, are items that you don't want to lose electrical power to. Unlike receptacles in your living room, kitchen electrical circuits tend to use more power. Many small kitchen appliances use resistive heating, like toasters, microwave ovens, coffee makers, toaster ovens, electric fry pans, electric griddles, things of that nature. Each of those items by itself poses no problem, but when you start running more than one of those items on the same circuit, you stand a good chance of tripping the circuit breaker. I guess as long as you know the breaker tripped, it isn't a problem, you can go reset it. But what if you are not aware that it tripped and it happens to be the same circuit as the freezer, or the refrigerator, is on? People are free to do what they want, I just happen to feel it would be a prudent idea to spend a few extra dollars and run additional circuits to the kitchen and keep certain appliances on their own circuit.

 

[Norcal]

I have always felt it is best to have certain appliances on their own circuit. Appliances like freezers, refrigerators, and to a lesser extent, dishwashers, are items that you don't want to lose electrical power to. Unlike receptacles in your living room, kitchen electrical circuits tend to use more power. Many small kitchen appliances use resistive heating, like toasters, microwave ovens, coffee makers, toaster ovens, electric fry pans, electric griddles, things of that nature. Each of those items by itself poses no problem, but when you start running more than one of those items on the same circuit, you stand a good chance of tripping the circuit breaker. I guess as long as you know the breaker tripped, it isn't a problem, you can go reset it. But what if you are not aware that it tripped and it happens to be the same circuit as the freezer, or the refrigerator, is on? People are free to do what they want, I just happen to feel it would be a prudent idea to spend a few extra dollars and run additional circuits to the kitchen and keep certain appliances on their own circuit.

Dishwashers, disposals, range hoods, built in microwaves, lighting, cannot be on the small appliance branch circuits, a refrigerator, or the power to supply the igniter for a gas range is permitted to be on those circuits.

How often does a breaker trip? Not often & they trip for a reason, same thing applies to GFCI's in kitchens, if it does trip it is most likely a defective appliance & that's why they are there, it used to make me nervous w/ fridges on GFCI protected circuits but they have been required kitchens for a long time & appliance manufacturers have built their products knowing that.

 

[James-W]

Dishwashers, disposals, range hoods, built in microwaves, lighting, cannot be on the small appliance branch circuits, a refrigerator, or the power to supply the igniter for a gas range is permitted to be on those circuits.

How often does a breaker trip? Not often & they trip for a reason, same thing applies to GFCI's in kitchens, if it does trip it is most likely a defective appliance & that's why they are there, it used to make me nervous w/ fridges on GFCI protected circuits but they have been required kitchens for a long time & appliance manufacturers have built their products knowing that.

Whether or not it is permitted, in my opinion at least, is not really the issue. Not trying to start an argument, but why would you NOT want to have appliances like your refrigerator or your freezer on a separate circuit? For the extra cost to run a few more circuits, does it not make sense to just do it since you are remodeling and have the kitchen torn apart anyway?

 

[volleyball]

That sounds fine and all but what if the refrigerator circuit trips and since there is nothing else on the circuit, you have no clue until the odor gets so strong.
There is code for many specialized circuits already.
I worked for a guy who wired up every receptacle on its own circuit. He had 4 panels. He thought he would save future issues but it was actually worse.
More is good. Even more is bad.

 

[TheEquineFencer]

Ummmm, IM surprised no one has mentioned this yet. why not install a MWBC(multiwire branch circuit)? Many homes use a MWBC for the dishwasher and disposal!

I was thinking the same thing. In electrical Class at Pitt CC, that's how we wired the houses we built and auctioned off.

 

[sberry]

It still takes up another space in a panel.

 

[Norcal]

I was thinking the same thing. In electrical Class at Pitt CC, that's how we wired the houses we built and auctioned off.

Snake oil, more commonly known as AFCI's has made multi-wire circuits less economical since a 2-pole AFCI would be needed, but at the current time, a multi-wire circuit for a DW & disposal is a good idea, they can be 15A, w/ 14 AWG.

The day is coming where the areas having GFCI protection & exempted from AFCI requirements will end, & both GFCI's,and AFCI's, will be required in kitchens, baths, & garages. Just my opinion, I like the idea of AFCI's but in reality the electrical contractors & users have been the test subjects for something that has never performed as claimed, now that GFCI requirements have been extended to under counter dishwashers, it also remains a matter of time before garbage disposals, receptacles behind refrigerators and any other exempted item(s) are required to be protected also.

 

[rlitman]

Just install a 2 gang box under the sink and run the 20a circuit to the line side of gfi to feed dishwasher.
Then come off of the load side of the gfi to feed a switch leg above cabinet ,then drop it back into the 2g box to feed a duplex recept which will be gfi protected to feed disposal.

Yep, which leaves you extra outlets for say a hot water dispenser.

The other option is to get a batch fed disposal, which does not require a switch.

 

[yeldogt]

I thought dishwashers needed a dedicated circuit ? Was that because they all had high wattage dryers back then ...that many don't have now?

Personally I like the batch feed disposers ... but have had to use a regular type on a couple of sinks due to the batch feed being too big --- I used the insinkerator push button control that mounts on the counter -- they are great.

We always hardwired the dishwasher -- but I am told that the code is changing in some locations.

 

[James-W]

That sounds fine and all but what if the refrigerator circuit trips and since there is nothing else on the circuit, you have no clue until the odor gets so strong.
There is code for many specialized circuits already.
I worked for a guy who wired up every receptacle on its own circuit. He had 4 panels. He thought he would save future issues but it was actually worse.
More is good. Even more is bad.

If the refrigerator is on its own circuit and the breaker trips, it tripped for a reason and the reason is most likely because the refrigerator developed a serious problem. That being the case you would need to get the refrigerator repaired, or replaced. Resetting the breaker is not going to fix the problem. But my thinking is, with the refrigerator on its own circuit, you won't have someone plugging in something else in an outlet on the same circuit and tripping the breaker. If they do that without realizing the refrigerator is on that same circuit, they may not reset the breaker right away. They may wait for the "man of the house" to come home and do it, and that would not be the best thing to do.

I am curious as to why having each outlet on its own circuit would make things worse. Would you please enlighten me on this? Not trying to put you on the spot, just curious as to why having more circuits would cause problems.

 

[yeldogt]

If the refrigerator is on its own circuit and the breaker trips, it tripped for a reason and the reason is most likely because the refrigerator developed a serious problem. That being the case you would need to get the refrigerator repaired, or replaced. Resetting the breaker is not going to fix the problem.

I am curious as to why having each outlet on its own circuit would make things worse. Would you please enlighten me on this? Not trying to put you on the spot, just curious as to why having more circuits would cause problems.

When I first started doing rehabs back in the 80's refrigerators did not need a dedicated circuit due to the low electric load .... they don't draw very much. Even less today.

Running separate circuits for every outlet would create a mess at the panel -- or four panels !

 

[Mustang51js]

Snake oil, more commonly known as AFCI's has made multi-wire circuits less economical since a 2-pole AFCI would be needed, but at the current time, a multi-wire circuit for a DW & disposal is a good idea, they can be 15A, w/ 14 AWG.

The day is coming where the areas having GFCI protection & exempted from AFCI requirements will end, & both GFCI's,and AFCI's, will be required in kitchens, baths, & garages. Just my opinion, I like the idea of AFCI's but in reality the electrical contractors & users have been the test subjects for something that has never performed as claimed, now that GFCI requirements have been extended to under counter dishwashers, it also remains a matter of time before garbage disposals, receptacles behind refrigerators and any other exempted item(s) are required to be protected also.

My understanding of the new code if your state adopts it that you will need to gfi protect the frig also,so will have to install a faceless gfi on counter next to frig. In the future it's just going to cause homeowners to spend more money with all these extra things that need to be done

 

[alfredeneuman]

The rules on GFIs made lots of sense when they were first adopted, and I still agree with their use, but I think they've gone a little overboard this time.

Both the snake oil AFCI and the "GFI everyplace under the Sun", are due to the large numbers of manufacturer's reps on the Code Making Panels that write the Code.
They want to sell more of their products, nothing more.

The snake oil AFCI rules even came out before any of them were commercially available, to be enforced at a future time.

A case of a solution in search of a problem

 

[justsam]

Yep, which leaves you extra outlets for say a hot water dispenser.

The other option is to get a batch fed disposal, which does not require a switch.

In the unlikely scenario of running the garbage disposal, 5-10 Amps, and dishwasher at 10 Amps, adding another 6 to 7 Amps for Hot water dispenser may not be a good idea.

Of course I am a big fan of individual circuits if it is my own home, and the AHJ may have their own way of wanting things done.

 

[wyliesdiesels]

The rules on GFIs made lots of sense when they were first adopted, and I still agree with their use, but I think they've gone a little overboard this time.

Both the snake oil AFCI and the "GFI everyplace under the Sun", are due to the large numbers of manufacturer's reps on the Code Making Panels that write the Code.
They want to sell more of their products, nothing more.

The snake oil AFCI rules even came out before any of them were commercially available, to be enforced at a future time.

A case of a solution in search of a problem

 

[oldberkeley]

Thanks for all the input.

I've decided to just go with a separate dedicated circuit for the garbage disposal.

I've got the switch installed on the countertop backsplash, ran 12-2 w/ground to a 20A breaker.

Under the sink, I'm going to use a 20A single outlet in a metal box.

My questions:

Not exactly sure about the correct way to fasten and wire the box itself. What I'd like to do is cut a small hole in the drywall and cabinet back and run the cable through that; use the two knockouts on the back of the box and two plastic button connectors to wire the box; then fasten the box directly to the cabinet back. No exposed wires.

Is this acceptable/correct?

TIA.