DW and GD MWBC

GOLDBIO · 09-13-2012, 01:01 PM

Hello All!! I have lurked here for a while now and I guess like everyone else, have found that I have a question that I am still unsure of after countless searches.

Anyways....Here is what I want to do. I have completely rewired my entire house and have been avoiding this one circuit. It is the last one left to do. I want to run a 20 Amp MWBC for my DW and GD. Obviously they would share a split receptacle with one side(GD) being switched.

I realize that this is a touchy subject after my searches

so I am not here to start a thread that has caused the same discussion (argument) to come up over and over about being on the same circuit vs. dedicated circuits and where it is found in the code.

What I haven't been able to find is a "crystal clear" this is how this is done. Whether it be written out or in a picture. I know I run 12/3 to the receptacle box and 12/2 to the switch, break the tab on the receptacle. Exactly where do all the wires get connected to the receptacle and switch?

Thanks for all the great info already out there and any help you guys can give me!

hammerlane · 09-13-2012, 01:08 PM

NOTE: no grounds shown for ease of drawing

GOLDBIO · 09-13-2012, 01:11 PM

Thanks hammerlane. Would it be much different if the 12/3 was ran to the receptacle box with the switch at the end of the run?

joed · 09-13-2012, 01:12 PM

You could do it that way however since a neutral is now required at switch boxes you would still need the three wire cable.

hammerlane · 09-13-2012, 01:14 PM

Here is a diagram where the power comes into the outlet location. the above diagram has power coming into the switch location.

NOTE: no grounds shown for ease of drawing

GOLDBIO · 09-13-2012, 01:15 PM

Quote:

Originally Posted by joed

You could do it that way however since a neutral is now required at switch boxes you would still need the three wire cable.

So doing it how hammerlane has it drawn would be acceptable? I am under the 2008 NEC.

kevinp22 · 09-13-2012, 01:16 PM

12-3 comes into receptacle box.
12-3 switch cable goes out of the box (2011 NEC requires neutrals at switches so you might as well run 12-3 instead of 12-2)

Pigtail white (neutral) and connect one neutral wire to the silver screw on the recetacle (DO NOT break the tab on the nutral side) and connect one to the white wire of the switch cable.

Break the tab on the receptacle between the two brass screws. Decide whether the top or bottom will be switched (lets assume top for the rest of my response)

Connect one of the hots (lets say the black) to the bottom brass screw on the receptacle.

Connect the other hot (lets say the red) to the black wire of the switch cable. Connect the red wire of the switch cable to the top brass screw.

Pigtail the grounds - connect the ground from the incoming cable, the switch cable and a wire to the green screw of the receptacle together.

At the SWITCH
1. Cap off the white wire
2. Connect the black and red wires to the 2 black switch terminals
3. If the box is non metallic, connect the ground from the switch cable to the green screw on the switch. Otherwise, pigtail: wire to green screw on switch, wire to green grounding screw in box, incoming ground on switch cable.

Plug corresponding appliances in

GOLDBIO · 09-13-2012, 01:17 PM

Quote:

Originally Posted by hammerlane

Here is a diagram where the power comes into the outlet location. the above diagram has power coming into the switch location.

NOTE: no grounds shown for ease of drawing

Thanks again Hammerlane. Sorry to hound you with questions. Joed has me worried about code compliance here. What you have drawn there is completely acceptable under the 2008 NEC right?

Anyone else wish to chime in?

kevinp22 · 09-13-2012, 01:18 PM

Quote:

Originally Posted by GOLDBIO

Thanks again Hammerlane. Sorry to hound you with questions. Joed has me worried about code compliance here. What you have drawn there is completely acceptable under the 2008 NEC right?

Anyone else wish to chime in?

YES but for the couple of feet of distance since you already have 12-3 run the 12-3.

hammerlane · 09-13-2012, 01:18 PM

Here is a neutral at switch location...just involves running a 12-3 to switch instead of a 12-2

Billy_Bob · 09-13-2012, 01:19 PM

If it is easier for you to understand, why not just run two separate wires and circuits to two separate outlets?
(Make life easy!)

For just one house, the extra expense is no big deal. However if you were a contractor building 50 new homes, then the savings could add up to big bucks. Thus the reason to do that.

GOLDBIO · 09-13-2012, 01:20 PM

Gotcha! Thanks guys! Couldn't be clearer to me now!!!

GOLDBIO · 09-13-2012, 01:22 PM

Quote:

Originally Posted by Billy_Bob

If it is easier for you to understand, why not just run two separate wires and circuits to two separate outlets?
(Make life easy!)

For just one house, the extra expense is no big deal. However if you were a contractor building 50 new homes, then the savings could add up to big bucks. Thus the reason to do that.

Money isn't the real issue. The issue is my panel is on the complete opposite end of the house that the kitchen is in. My panel is in the basement and I would just rather run one line instead of two. Since I am drilling like 50 holes through joists for each circuit, it cuts the work down a little.

I agree that running 12/2 to each one is a lot less confusing.

rjniles · 09-13-2012, 01:24 PM

I would run a 12-2 for the switch loop. Does anyone think you would ever put a dimmer or a timer on a disposer? Also the poster says he is under 2008.

hammerlane · 09-13-2012, 01:31 PM

Quote:

Originally Posted by rjniles

I would run a 12-2 for the switch loop.

WHy would you use 12-2 for the switch loop?