Kitchen Multi-wire Circuits

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  #1  
Old 09-20-07, 03:08 PM
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Question Kitchen Multi-wire Circuits

I plan to wire a kitchen counter top receptacle, and another item (dishwasher or light fixture) on a multi-wire circuit (12/3 cable: two separate hots, shared neutral and shared ground).

This is acceptable for kitchen counter top receptacle rules, correct?
 
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  #2  
Old 09-20-07, 03:27 PM
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Yes,

IMO. I wouldn't, Don't tax the neutral.
 
  #3  
Old 09-20-07, 03:36 PM
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Multi wire circuits don't tax the neutral any more than a normal circuit. As matter of fact the neutral carries less current than a normal circuit if both circuits are being used.
 
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Old 09-20-07, 04:35 PM
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Thank you.
So this OK by NEC code, and from what Joed says safe too.
Anyone else care to confirm?
 
  #5  
Old 09-20-07, 04:39 PM
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Not an electrician but this method of wiring kitchen receptacles has been used for years. As far as I know it's still code.
 
  #6  
Old 09-20-07, 05:58 PM
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It is legal. It is safe. Provided it is wired properly. The voltage between the two hot wires MUST be 240 volts. The easiest way to accomplish this is to use a 240 volt breaker.
 
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Old 09-20-07, 06:40 PM
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The specific disadvantage of multi-wire circuits in kitchens is that you cannot use the downstream protection feature of GFCI receptacles with a shared neutral. If this circuit serves more than one receptacle, each location needs its own GFCI device with only the LINE terminals connected. It is legal to do so, but could be inconvenient.
 
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Old 09-20-07, 07:14 PM
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You can use the LOAD side (downstream) protection of a GFCI on a multiwire circuit. You just can't share the neutral on the load side or use split wired receptacles on the LOAD side. You have to split the circuit and run it as two separate circuits after the GFCI LOAD connection.
 
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Old 09-20-07, 07:27 PM
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*The easiest way to accomplish this is to use a 240 volt breaker.*

You must use a 2 pole breaker on multi wire. In the USA.

Splice /pig tail the neutral, at the 1st junction.

What is the advantage to this (multi wire SA ckt)?
 
  #10  
Old 09-20-07, 08:19 PM
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Originally Posted by lectriclee View Post
You must use a 2 pole breaker on multi wire. In the USA.
This is not a requirement as far as I know. There are certain situations where you must do so, but not in all cases. From where did you get this information?


If I were putting in this circuit, I would use 12-3 to the dishwasher receptacle or junction box, and then use 12-2 to the counter top GFCI receptacle LINE side. You can then use the 12-2 and connect any additional regular receptacles to the LOAD side of the GFCI.
 
  #11  
Old 09-20-07, 09:09 PM
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Just my opinion, but except in a small number of situations, multiwire circuits aren't worth the trouble. There are many pros and cons, but in most cases, the cons outweigh the pros.

Yea, yea, I know. There are cases where the pros outweigh the cons, but that's only for very specific situations. There's nothing (so far) in the description of this application which would suggest to me that this is one of those situations.
 
  #12  
Old 09-20-07, 09:31 PM
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I agree with John it ain't worth the trouble. If you insist... do it the way Joe and Bob suggested. It will avoid a lot of other headaches. the cost between a roll of 12/3 G and two rolls of 12/2 G is just a few dollars. I just picked up 250 feet of 12/2 G at the big box on a whim visit out of nothing else to do and got it for $57.50 on closeout. Normally around 80.00 unboxed.
How the heck???..... cause they were stocking new packaging from a new vendor. The vendor was cerro-wire and the wire I got was Simpull by southwire. Guess who owns cerro-wire .. go figure. Besides I think that yellow stuff is pretty.

Oh yeah forgot what I was going to say....(i'm still in shock)..the only time I like to run a multiwire is for long runs where voltage drop is a consideration and only then if load operation on each leg is equal or close to equal.

Roger
 
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Old 09-20-07, 10:34 PM
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I'll add my vote for not using multi-wire circuits to those of Roger and John Nelson.

They are certainly legal and in some instances they do make sense but as a rule I do not like multi-wire circuits in residential applications.
 
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Old 09-20-07, 10:44 PM
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I will step in here as well

I useally have no issuse with the MWBC but my main condseration is that when the average " person " working on MWBC and get the netural unhooked it can do funny things along the way.

and the MWBC is kinda tricky to deal with it.
i done all the time with commercal verison and i did see how it happend if not used right alot of either or will show up

anway what other saying in here just keep it simple that will useally do the best way


by the way the NEC did change the code it will be in effect after 08 cycle all MWBC will use common tied breakers [ some states will adpot this later date ]

Merci , Marc

it is legal to used the MWBC for resdentail useage
 
  #15  
Old 09-20-07, 10:56 PM
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I'm using the Black and Decker Complete Guide to Home Wiring kitchen as my guide for this remodel. It has the two counter circuits on one 12/3 cable with GFCIs at each receptacle. I had to buy 12/3 for my electric oven circuit anyway. I have a peninsula circuit and the dishwasher to wire so I thought why not do it with the leftover 12/3. I guess I just like the idea of 'two birds with one stone'.
 
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Old 09-20-07, 11:01 PM
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Originally Posted by Romy07 View Post
I'm using the Black and Decker Complete Guide to Home Wiring kitchen as my guide for this remodel. It has the two counter circuits on one 12/3 cable with GFCIs at each receptacle. I had to buy 12/3 for my electric oven circuit anyway. I have a peninsula circuit and the dishwasher to wire so I thought why not do it with the leftover 12/3. I guess I just like the idea of 'two birds with one stone'.
HOLD on a min please before you do that please check the oven specs it will tell you what amparage it requred most oven i know useally speced for 30 amp circuits some at 40 which you can not use the 12-3 at all because the 12-3 is rated for 20 amp only and the wall oven useally run for 30 amp circuit unless the manufacter of that oven spec'ed diffrent

that why i want to warn ya before you do used that wire and end up redo again when the instruction manual say requred XX size of wire

Merci , Marc
 
  #17  
Old 09-20-07, 11:10 PM
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Thanks. I checked when I did my load calc. The manual and customer service at GE say it is a 20 amp oven. Just a built in oven no range on top.
 
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Old 09-20-07, 11:26 PM
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Ok i just want to double check to make sure you dont make a mistake which it do happend from time to time.

as long the instruction manual say 20 amp circuit and use the 12-3 you are ok on that part

[ normally i just wired in 10-3 to cover my butt because some wall oven have pretty powerfull stuff in there ya never know lol but once a while i will run into wall oven that reqired a 40 amp circuit that espcally true with top of line wall oven with all the bell and whistle ]

Merci , Marc
 
  #19  
Old 09-20-07, 11:47 PM
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No dishwasher or lights can be on this multiwire.

You cannot put the dishwasher on the 20 amp small appliance circuit nor can you put a kitchen light on it. If this multiwire circuit serves kitchen counter tops and your going to use the multiwire to satisfy the 2 20 amp small appliance circuits you cannot put the dishwasher or any lights on either leg of the multiwire. Code section prohibiting this is 210.11(c)(1) and 210.52(b)(2)

Roger
 
  #20  
Old 09-21-07, 12:00 AM
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I already have two 20 amp small appliance counter top circuits.
This dishwasher or lighting plus countertop multi-wire is the THIRD countertop circuit. Is this case OK? If not I'll just run an extra cable.
 
  #21  
Old 09-21-07, 12:05 AM
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Yep IMO that works just fine...



Roger
 
  #22  
Old 09-21-07, 12:07 AM
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Ok thanks everyone.
I'm going to bed. It's past midnight PST.
 
  #23  
Old 09-21-07, 02:09 AM
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2 POLE;

Bob, I may have misinterpreted that part, or missed something. (that book is fat).

I will read it more closely today.
 
  #24  
Old 09-21-07, 08:26 AM
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I looked at multiwire circuits for the kitchen countertops and decided it wasn't worth it, especially if I have to split the circuit for GFCI protection anyway. However, my AHJ requires the dishwasher and disposal to be on separate circuits, so a multiwire makes sense there. I'm using a two pole breaker because I want to make sure both halves of the receptacle are dead when I cut the power.
 
  #25  
Old 09-21-07, 08:30 AM
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Originally Posted by biking_brian View Post
I'm using a two pole breaker because I want to make sure both halves of the receptacle are dead when I cut the power.
No, you are using one because its required. In this instance (both hots connected to the same device), a common trip is required.
 
  #26  
Old 09-21-07, 08:45 AM
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Thats fine Brian. Code actually requires (mandatory) that you have a common trip double pole when a multiwire lands on one yoke (device). Also for receptacles on a multiwire serving a general purpose circuit or any others for that matter (receptacles) that the neutral will not be broken if the receptacle is removed. so this means you need to pigtail it to the receptacle silver screw.

http://ecmweb.com/nec/electric_branch_circuits_part/

http://ecmweb.com/mag/electric_multi...anch_circuits/

Roger
 
  #27  
Old 09-21-07, 08:45 AM
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Thanks for the clarification. My original basis was that the two pole breaker was required, but then skimming this thread, I got the impression that it was optional - but had forgotten we weren't always talking about two hots to the same device in this thread.
 
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Old 09-21-07, 01:34 PM
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Originally Posted by racraft View Post
No, you are using one because its required. In this instance (both hots connected to the same device), a common trip is required.


Yup, Right again. I got myself confused.
 
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Old 09-21-07, 05:53 PM
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Originally Posted by Romy07 View Post
I already have two 20 amp small appliance counter top circuits.
This dishwasher or lighting plus countertop multi-wire is the THIRD countertop circuit. Is this case OK? If not I'll just run an extra cable.
I don't think I saw a correct reply to this yet. The "plus countertop" part of this is NOT allowed.

You cannot have anything else on a kitchen "receptacle" circuit. This rule does not go away once you meet the "two S-A circuit" requirement. The S-A circuit requirement is "two or more 20-ampere small-appliance branch circuits shall be provided for all receptacle outlets specified by 210.52(B)."
Two or more. If the circuit feeds general receptacles in kitchen or related rooms it is a S-A circuit.
See 210.52(B)


210.52
(B) Small Appliances
(1) Receptacle Outlets Served
In the kitchen, pantry, breakfast room, dining room, or similar area of a dwelling unit, the two or more 20-ampere small-appliance branch circuits required by 210.11(C)(1) shall serve all wall and floor receptacle outlets covered by 210.52(A), all countertop outlets covered by 210.52(C), and receptacle outlets for refrigeration equipment.



 
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Old 09-21-07, 05:56 PM
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YEAH!!!!!

We got vB codes back!!!!!!!!

THANK YOU!!!
 
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Old 09-21-07, 06:57 PM
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Thumbs up

The little things in life !! NO?
 
  #32  
Old 09-21-07, 07:17 PM
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Speedy

I've actually been having some trouble reading english lately.... But.....

I know about the "plus countertops" and the 2 or more. If I'm understanding this he is going to serve a dishwasher and maybe a light on one leg and the counter top receptacle on the other leg of the 20 amp... multiwire .... this still would not be ok? I suppose if his local code requires dedication to the dishwasher he may be out of luck but lets say he doesn't do the light. So he has one leg to the dishwasher and one to the peninsula countertop receptacle, that won't work as far as code goes?

As an aside the inspectors here would likely give you exception for a light with the dishwasher. Unless it was that one you see at the carnivals.....

Roger
 
  #33  
Old 09-21-07, 07:56 PM
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It's all good.

MWBC. IMO

Ckt #1 to the peninsula, GFI of course. (neutral spliced)
Ckt #3 to the DW and light.

The 2 must be seperate.

Barring any local code, 05 allows this.

I would not want it that way. (Personal reasons only)
 
  #34  
Old 09-21-07, 09:17 PM
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According to my interpretation of the code, it would be legal to put the dishwasher and lighting circuit on the same 3-wire as the counter top circuit. Article 210.4(A) States that a mutlwire branch circuit can be considered 2 seperate circuits. Therefore, the lighting should legally be able to share a neutral with the counter top small appliance branch circuit.

I would prefer to keep the lights on a seperate circuit from the dishwasher though. Won't get the dimming effect that way then.

I prefer to use mutliwire branch circuits, because it's cheaper and there's less cables to pull. It also means less spaces used on the neutral bar. I really don't see any downsides to it in residential as long as you know what you're doing. Even if there's GFCI protection involved, you just split the cable up at or before the GFCI (assuming you're protecting at the outlet and not the breaker). So you run 2 seperate cables from there..... At least you made your homerun quicker and easier.
 
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Old 09-21-07, 09:55 PM
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Let me throw this at you Brew and I hope I don't bring the internet police down on me.

In your area if you were to be the one doing this remodel and you had already brought 2 20 amps to the receptacles on a multiwire for the countertop. And lets say your not dealing with a dishwasher to make this a little more complicated. And you added a pennisula with a duplex receptacle to the kitchen. You ran a 20 amp 12/2 G to that one duplex receptacle and then caught one light.

If you brought that to your inspectors attention and asked for exception would he flag you for catching that one light?

Roger
 
  #36  
Old 09-21-07, 10:28 PM
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Roger,

It possible if it is on MWBC or 12-2-2 romax® cable on it it good chance you can split it off from there but some area code have very thin line to crossover on this code.


I have simuair sisuation but this is on commercal area and we were allowed this but resdentail area it kinda pretty much the HI [ home inspector ] say so if you feel " not right " with this just ask them the code referince to back it up.

IMO kitchen area is one of very few place i have to watch very carefully with MWBC

Merci , Marc
 
  #37  
Old 09-22-07, 12:55 AM
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I'm just giving my interpretation of the code in that situation. You've read my opinion, so I'm not sure exactly what you're asking. Ultimately, the AHJ has the final say. Some inspectors are so picky that they won't allow legal installations out of personal preference. There are others that will stand there and talk your ears off while the building's burning down around you and they'll give it a pass.

I don't see anything that technically makes it illegal. I personally don't feel that there's anything wrong with it. If the inspector's a harda**, he might flag it. There are others that would rather tell me their life story, won't bother to look into how it's all wired, and then I'd have to remind them to sign-off on the inspection as they leave.
 
  #38  
Old 09-22-07, 02:33 AM
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I was curious because we would get the exception 9 times out of ten around here.

You didn't give an opinion on the countertop receptacle...plus light you gave one on the dishwasher ..plus light....big difference.

BTW... you need to lower your defensive shield a tad. If I have said something that ticked you off in a previous post somewhere let me apologize and lets start over. You keep talking down to people and I can see why you have so many problems. Are you somebody we should know? We are all here to learn and give advice to those who ask. We are not perfect. Your demeaning of inspectors didn't impress me one bit. I think it was totally inappropriate... so climb down off your thrown and join the rest of us poor common folk.

Roger
 
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Old 09-22-07, 03:57 AM
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You are quite right Roger. I mis-read post #20, and I see you DID address the "not mixing lighting and the DW with the S-A circuit" issue previously.

Sorry 'bout that.
 
  #40  
Old 09-22-07, 05:16 AM
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Oh Heck Speedy just forget it.

Know why I knew? .....I learned it from you about a year ago...... Still have it high lighted (with penciled in notes) in my code book out in the truck.

I know how it feels to misread.....look here

http://forum.doityourself.com/showthread.php?t=318431

Jeez that was a bad one.


Roger
 
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