Garbage Disposal Wiring


My house doesn't have a Garbage Disposal (nor do I foresee wanting one) but since I'm replacing drywall behind the kitchen sink and adding another outlet over the countertop, I want to run the wires for a GD while I'm in there. It might make the house more desirable if I ever decide to sell. I'm thinking of having a double switch box to the right of the sink, with one switch for a small flourescent light mounted over the sink and the other switch for the GD.
Here's my questions:
1. Are GD's usually hardwired straight from the switch near the sink, or do they plug into an outlet under the sink which is switched on and off by the GD switch above?
2. Does the wiring code allow an outlet to be mounted under the sink, in close proximity to the hot and cold water inlets? If so, does it have to be GFCI? If outlets are permitted under the sink, is it best to install them high (above the water inlets) or down low?
If outlets aren't allowed under the sink, I plan on installing a junction box under the sink (again: high or low?) and running the wires from the GD switch down to the JB, putting wire nuts on the ends of the wire, and a cover on the JB. If the next owner is someone who can't live without a GD, at least the wiring will be there already.
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I don't know if current code makes a specification. Non GFIC outlets were allowed under the sink. Best to use an adjustable box so that it will flush out to the cabinet back. If just using a sink front a regular box is fine. I like to put them above pan height so somewhere around 20-24" off the floor to the bottom of the box..
They can be hard wired or plug in and it should be a dedicated 20 amp circuit.
I prefer plug in because that provides an absolute disconnect at the point of service. Often 12/3 wg will be pulled and the dishwasher gets one leg of a split duplex and the garbage gets the other. Just be sure to get both breakers on the same leg so there is no potential for 220 in the box.
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Colbyt
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My understanding was that if you did it that way you HAD to use opposite legs (aka Edison circuit,) otherwise you have the potential for the neutral to be carrying 2x the rated amperage...? Also you need to use breakers with the handles tied together.
nate
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My understanding was that if you did it that way you HAD to use opposite legs (aka Edison circuit,) otherwise you have the potential for the neutral to be carrying 2x the rated amperage...? Also you need to use breakers with the handles tied together.
nate
You are correct. You never wire an Edison circuit with both hot legs on the same leg
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My understanding was that if you did it that way you HAD to use opposite legs (aka Edison circuit,) otherwise you have the potential for the neutral to be carrying 2x the rated amperage...? Also you need to use breakers with the handles tied together.
nate
I have never done it that way. And I do agree that you are right about the Edison circuit.
My son's house is on a split duplex. I will have to take a look at his panel box and see how it was done.
Colbyt
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The two legs on an Edison, or Multiwire branch circuit, have always had to be on opposite legs of the service, and with the new code, they must be attached to double pole circuit breakers

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I'll let others speak the code issues about outlets under the sink, but I will toss this out:
I have always heard (and agree) that the GD switch should be separated from other switches in such a manner as to prevent it from being turned on by mistake.
When I installed mine, I put the switch on the opposite side of the sink from the light switch, which put it behind the dish draining rack. It's just inconvenient enough that you have to *want* to turn it on - you would never accidently hit that switch when trying to turn on the light.
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Yep, good idea. My approach was to use a different color switch. Every switch and receptacle in the entire house are white -- except the switch that controls the disposer. That's gray.
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You don't need a switch on the counter top for a disposal. Many have the switch built into the drain stopper, to prevent sticking your hand in and turning it on. If you want a switch, it may be advisable to install it in the sink base cabinet, so a deliberate action must be taken, to turn it on. Disposals use only a small amount of electricity, so a 15 amp circuit is fine. You cannot wire it to your counter outlet circuit. You can install outlets in the sink base, and they do not need to be GFCI protected.
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"In" meaning "inside". You don't want to have the switch on the outside of the sink base cabinet where it could easily be bumped, or within reach of a child.
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"In" as in, you have to open the cabinet door to get to it.
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*They can be wired either way. Some disposals come with cords already attached. I prefer cords to make it easy for the plumber to install and remove without having to call an electrician.

*Yes it is permissiable to wire an outlet under the sink and it is not required to be GFCI protected though it is not a bad idea. I usually mount the boxes where they are the most accessible which is usually on the cabinet side close to the cabinet door. It is a royal PITA to work on a junction box or receptacle way back inside especially in a corner cabinet. Keep it up high so as to not interfere with household items.

*I think that is your best bet. Use a 4" square box. Leave extra slack on the cable in case it needs to be relocated or pushed aside for plumbing. Use a 20 amp circuit and keep it separate from the lighting.
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And don't bother with a wall switch. Since most better quality disposal units don't need them, why have a blank plate visible on the wall or a switch that does nothing, as every visitor will use it to try to turn on the lights, and probably even your wife, much to her anoyance. You don't want her anoyed.
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.
The stores are chock full of quality disposals that need a switch of some kind and most are of that type. As someone else stated, the kind that require the disposal plug be installed to turn it on instead of a switch work in batch mode are a royal PIA.
Another alternative is to use a switch that mounts in a hole in the sink, similar to a soap dispenser, etc. These are air based at the sink and work the actual switch which is located safely out of the way under the sink. They can be used with any disposal.
why have a blank plate visible on the wall or a

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Josh wrote:

What about the dishwaser?
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HeyBub | 2009-09-16 | 7:01:31 PM wrote:

A switch for the dishwasher is--well, I don't know what it is, but it isn't good.
My first house had such a switch. One night, after I'd lived there for years, I spent an hour taking the dishwasher apart to figure out why it wouldn't work. Someone had turned off the switch that had never been turned off before.
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SteveBell wrote:

I'm sure you flipped off the dishwasher switch before disassembling the machine!
It would be shocking if you didn't.
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HeyBub | 2009-09-17 | 9:40:07 AM wrote:

Well, since I forgot there even _was_ a switch, it being hidden way back in the corner behind the canisters and all, I didn't flip it. I assumed (yeah, I know) the timer had failed and took the door apart.
When I discovered no power to the timer, I started following wires back toward the wall. When I found no power at the junction box, I remembered the %^*@# switch. Then I had to put the thing back together again.
Lesson learned: Check power from the wall first.
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Josh wrote:

Generally the same outlet is used for the dishwasher and disposal. The disposal side is switched, the dishwasher side isn't. Avoid at all cost, disposals with switches in the disposal plug. If you don't want a wall switch, there are momentary contact switches that you install in the countertop.
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