Dishwasher and Garbage disposal on one circuit?

I don't know about code. but mine have been wired like that for 35 years now. In my case there is a surface mounted duplex receptacle in the sink base. Both appliances have a cord plugged into it. If you have to work on them you can just unplug.

It is recommended to put the GD and dishwasher on it's own 15 amp circuit or use a 20 amp circuit if you want to put them both together.

The average DW can pull 10 amps and the GD can be between 4 and 8 amps. If running the DW and turning the GD on, you will most likely trip the breaker at 15 amps since both will have a spike amp at start up.

Yah, that's what I did. Dishwasher, disposer and water softener all on one 20A GFCI Square D breaker. Hasn't tripped in 20 years.

If I am not mistaken, the first "authority" on this is the installation instructions for each appliance. AFAIK, the NEC requires that you follow the installation instructions provided by the manufacturer. If either of the instructions say that it must be on a dedicated circuit, then the NEC essentially says that it must be on a dedicated circuit.

Of course, local code trumps all.

The only way you have a chance of it working 100% of the time is if you use a 20a breaker. That is fine on 12 ga. The other option is to use 12/3 nm a 2 pole breaker and make a multiwire circuit with 2 separate 20a circuits. (the most common way of dealing with this) Land it in a 4x4 box and use 2 GFCI receptacles to be compliant with the current code.

Thanks. I am doing the wiring today. And, overnight, I was thinking that I should do it as you described that yours is set up -- with a receptacle in the sink base and have each appliance plugged into the receptacle rather than directly hardwiring them. So, that's the plan.

Thanks. I'll use a 20-amp breaker since it is 12 ga. wire. And, I am going to set it up so each appliance plugs in rather than hardwiring the appliances. I already ran the 12/2, so I am going to skip the option of using 12/3 and a double pole breaker.

Which raises the other code question, if it's code compliant to put a cord and plug on a piece of equipment where it does not come with one and the install instructions don't say it can be used with a cord. I think that's come up before and the answer is no. Not saying this is a big safety issue or anything, just that I think that issue exists. Gfre?

re: "and the install instructions don't say it can be used with a cord."

That can be taken 2 different ways and I wonder if it depends on how it is worded - or not worded.

If the instructions say "You may not use a cord and plug on this appliance" then that's easy. The NEC rule says that you must follow the manufacturer's installation instructions, so you can't use a cord and plug. That's pretty clear.

If the instructions say "You may use a cord and plug on this appliance" then that's easy too.

But what if the instructions don't even address it? Does the NEC require that the instructions explicitly say that you may use a cord and plug or is the absence of both a Can and Can't statement enough to allow it?

I'm a little surprised.

I looked at a Maytag installation manual for a dishwasher, and it shows how to either attach a cord and plug or how to direct wire it. In the back of my mind it had to be direct wired, but not so.

I've not installed a dishwasher, but I've done a disposal a couple of times , and I direct wired it.

I also looked at a disposal installation manual, and it was silent on the s ubject, BUT it did say there must be a power switch with the off position m arked and it must be within view of the opening. I hope you remembered you need to turn this thing on and off, unlike a dishwasher that has its own c ontrols.

ow to either attach a cord and plug or how to direct wire it. In the back of my mind it had to be direct wired, but not so.

es, and I direct wired it.

subject, BUT it did say there must be a power switch with the off position marked and it must be within view of the opening. I hope you remembered y ou need to turn this thing on and off, unlike a dishwasher that has its own controls.

re: "it must be within view of the opening"

What "opening" does the manual refer to? Are they referring to the opening of the cabinet under the sink?

For the disposers that I have installed, I have chosen to mount the switch above the counter so I don't have to open the cabinet, bend down to use the switch, etc. However what I made sure to do was the mount the switch in an "isolated" spot so that it wouldn't be confused with light switch, etc.

For example, in my kitchen it is on the opposite side of the sink from the switch for the light above the sink and also behind the dish rack. That makes it *slightly* inconvenient, and somewhat hidden, which was done on purpose.

In my parent's kitchen, there are switches on both sides of the sink, so I mounted the switch directly behind the faucet. The user has to reach around the faucet to operate it and it is labeled so that it (hopefully) won't be confused with a light switch.

re: "I hope you remembered you need to turn this thing on and off"

Just FYI... There are batch feed units that don't require an electrical or air switch. The power is controlled by the "stopper" or cap that you put on the unit and then turn to engage. (I am not a fan of that style. I like to turn mine on and then rinse debris down the drain while it is running.)

how to either attach a cord and plug or how to direct wire it. In the bac k of my mind it had to be direct wired, but not so.

imes, and I direct wired it.

he subject, BUT it did say there must be a power switch with the off positi on marked and it must be within view of the opening. I hope you remembered you need to turn this thing on and off, unlike a dishwasher that has its o wn controls.

I would think it's the opening of the disposal, so that the opening and switch are within sight of each other to prevent someone from putting their hand in, while someone else unaware is working a switch.

One of those air activated switches might be the best choice. You can turn it on with wet hands, while using the switch, instead of having to deal with a wall switch. Never used one though, so IDK how well they work. Never seen one with a switch underneath the cabinet.

.)

The Insinkerator owner's manual allows either cord and plug or permanent connection.

From the instructions, so it would be required to meet code:

What "it" are you saying would be required to meet code?

The stuff past the colon would be required to meet code. "This disposer requires a switch" etc.

"...except if using an air switch or batch feed accessory"

That's why I asked about your use of the word "it". If your "it" meant a marked switch within sight of the disposer sink opening, then "it" is not required in all cases because exceptions are allowed.

Just trying to clarify the situation, that's all.

As long as it is an option from the manufacturer, it is fine. There may be a question of listing if the cord is field installed and it is not the exact cord the appliance manufacturer uses but for all practical purposes, the code pretty much stops at the face of the receptacle.

I wired the GD and DW to separate poles of ganged 15A (non-GFCI) breakers. There is a momentary-contact switch for the GD.

Perce

Well, the deed is done. Both the dishwasher and the garbage disposal are installed and are working. Both are on the same 20-amp circuit using 12/2 wire. Both are plugged in to a duplex receptacle that is mounted under the sink. The receptacle is "split" where one side (the garbage disposal side) is controlled by a wall switch on the wall above the countertop near the sink. The other half of the receptacle is always hot -- not switch controlled -- and the dishwasher is plugged into that side.

The "garbage disposal" is an Insinkerator Badger 900 Food Waste Disposer. The dishwasher is a Whirlpool Model WDF320PADS1. The installation manuals for both state that they can be either direct wired or wired with a corded plug. We did the corded plug approach.