I’m planning on adding two new kitchen outlets to my 55 year old house which presently has only one outlet. I want to install a 20 amp GFCI at each location, each on their own breaker.
I want to run one hot lead from a 12/3 cable to the first outlet and then connect the other hot lead from the 12/3 cable to a 12/2 cable running to the second outlet, sharing a common neutral wire.
Can the two GFCI’s share a common neutral wire?
Replies
Yes.
Spheramid Enterprises Architectural Woodworks
"Success is not spontaneous combustion, you have to set yourself on Fire"
huh ?it's not that easy !.
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The question was can they share the neutral, not how. True there are a couple of subtleties here, ie the two breakers being on different legs/busses and pigtail the neutral before the first one.
Bill will be along soon and set us all straight (;-).
Thanks Rasconc. You are right on the money with the pigtail and the two breakers being on different busses. That's what I was intending to do but wanted to keep my message short and to the point.
WHY?It seems that everyone got it right except for Wallyo and PB corrected him.Looks like I am working myself out of a "job"..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Bill question for you on this one then so there is no confiusion to any one else coming along.He is dead ending the outlets in effect, 3-12 to the first box , pigtail the white off of it to GFCI white line, red connected to the hot line in on the GFCI first one done. Black from the 2-12 to the black of the 3-12 connect the white to the pig tailed white and the white of the 12-3 then run that to the second GCFI hook up as normal.Okay first question does anything change if the white is not pigtail but both go into the white line tab of the first GFCI?Second question does any thing change if you use the load side on either one or both GFCI to feed other outlets down stream?Third question if the answer to question 2 is no you can not feed other outlets off the load side, would it be just bad pratice to wire it this way should someone else in the future decide to tap off outlet one to add a third outlet?Wallyo
that was my point. using SP breakers could cause problems in the future if someone decides to move one of those and puts it on the same leg .. I think it is a bad practice in a NM wired house IMO, all in the name of saving a few $ for a second neutral....!.
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Good question but I don't think you can share a neutral on a gfci, and have both work properly, they will be constantly thinking there is an imbalance if one has a heavy load and the other a lite load, just my gut feeling though. Might be able to do it with a 20 amp 240 gfci breaker in theory and split it to two outlets, but if you were to do that it would be cheaper to run 2 separate 12-2's one to each outlet and be done with it.
Even though I don't know the answer it is a very good question.
Wallyo
It does appear that you do not know the answer (:-)
"Good question but I don't think you can share a neutral on a gfci, and have both work properly, they will be constantly thinking there is an imbalance if one has a heavy load and the other a lite load, just my gut feeling though. Might be able to do it with a 20 amp 240 gfci breaker in theory and split it to two outlets, but if you were to do that it would be cheaper to run 2 separate 12-2's one to each outlet and be done with it.
Even though I don't know the answer it is a very good question.
Wallyo"
I twice commented that Flips posted a very good question. There is more confusion as to how to properly wire a GFCI correctly then any other electrical question.I clearly admitted to not knowing the answer, just put my thoughts down as to why I thought it would not work. There is no need to rag on me any further, if you want to point out to me technically as to why my thoughts are wrong that is fine, repeating what I wrote does not add anything to the discussion, we are all here to learn as well as give advice. I was just trying to stimulate the conversation.WallyoEdited 2/29/2008 1:31 am ET by wallyo
Edited 2/29/2008 1:32 am ET by wallyo
Sorry to offend, I guess I misdrew my smiley face. When you lead off with I don't think you can''' after saying it is a good question it does kind of muddy the water.
I hesitated to mention the search feature where one could have found at least three iterations of this one in recent history. I have tried to search many times and blown right by the info I was looking for.
As later pointed out there are some decent reasons to not use the "multiwire circuit (12-3)". You never know what someone may do later down the road and move one of the breakers to the same buss as the other one.
I started to mention to the OP that he might want to consider extending each of his two new GFCI recpt off the load side as you mentioned. If it is too much to try to fish then jut put a two gang box and add a standard duplex (or decora style) in the other space.
I will try to not kid someone I do not know so late at night. (;-})
Bob
I have not found the search feature very useful my self even when trying to find an item posted just a couple of weeks back. No offence taking just was not in the mood for being razzed. By a good question I meant as I stated GFCI have a lot of confusion alone the second confusing item to the novice is the Edison circuit, here he combined both.Read on to my next post to Bill I cannot figure out if you can send a post to more then one aside from "ALL"Wallyo
"Okay first question does anything change if the white is not pigtail but both go into the white line tab of the first GFCI?"Not electrically.But the code does not allow this. The reason is that if connection at tje receptacle is loose then you loose downstream receptacles. For a case like this is it not problem. But in general for multiwire circuits (shared neutral) if the neutral is broken then you can get 240 across 2 (sets) of receptacles and that across each one depends on what loads are inuse. Thus the code requires the neutral to be pigtailed.BTW, the service to a house is a big multiwire circuit. And if neutral is lost or damaged then you can have the same problems."Second question does any thing change if you use the load side on either one or both GFCI to feed other outlets down stream?"It depends on how they are wired. You can break it into 2 separate circuits. Run 12-2 form each GFCI to their downstream receptacles. You CAN NOT run 12-3 and keep the shared neutral. The current that goes out the hot load terminal has to return through that GFCI load neutral or else it trips. If you try to connect a shared neutral to the load side on one or both GFCI's then the same current does not return through the same GFCI and will trip. As you said earlier you can use a 2 pole GFCI breaker where all current (both hots and neutrals) go through the single sense coil that detects unbalance."Third question if the answer to question 2 is no you can not feed other outlets off the load side, would it be just bad pratice to wire it this way should someone else in the future decide to tap off outlet one to add a third outlet?"Well you can tap off the first receptacal, as long as you don't try to run 12-3 off the load side of both, either on the line side or the load side.But in general a lot of electricans, such as MD3, dont' like them in residences. More because you can have a hot circuit in the box althrough the breaker has been tripped and that ONE receptacle is dead. But the other leg that just passes through is still hot and you can have an active load and if the neutral is opened it can be hot from the downstream load on the other leg.Also wires can be put on the wrong breakers so that they are on the same leg and the neutral is the SUM of both loads. BTW, I understand the 2008 NEC requires a tye rap at the panel around the wires in a mutliwire circuit to clue people in the future that it is a multiwire circuit.Other electricans think that it is a valid method to efficiently run circuits. It is most often use for kitchens. But some will run it to far bedrooms and then split it..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
>>BTW, I understand the 2008 NEC requires a tye rap at the panel around the wires in a mutliwire circuit to clue people in the future that it is a multiwire circuit.<<
I like that idea. I have always tagged them at the panel - just trying to watch out for "the next guy".
JimNever underestimate the value of a sharp pencil or good light.
BillJust a couple of observations:Wiring GFCI's has had so much confusion locally on doing it right, especially when Hot Tubs are concerned, that a HOME OWNER is no longer allowed to pull a permit and do it himself. The permit must be pulled and the work performed by a licensed electrician on all HOT TUBS. The inspectors got tired of call backs due to HO's doing it wrong.Can't remember but the last time I did an Edison circuit on my sisters house helping my brother inlaw the inspector did not like it much, not that we did it wrong just the reasons mentioned already someone goes and in the future moves a breaker to the same side were his reasons. He even said it is within code, but he thought they should not be allowed in residential. The part I cannot remember is I think he made us put a tie across the two breaker handles in effect making it a 240 breaker. I will look next time I am there. I agree with JTC1 the cable tie is a good idea, you learn every day.Third point (I will check with my electrician when I see him on Tuesday to see if this is another local thing), but the last kitchen remodel I worked on (the home owner used their own Sparky). They wired the outlets with 12-4, for those not familiar white, black, red and white with red stripe. I had never seen 12-4 before asked why and I thought they said it is what code called for, that 12-3 was no longer allowed for split circuits that was a few years back, so code could of change or it is a local thing.WallyoI must add a third edit and correct myself before I get run over the coals, it is not 12-4, but the correct calling appears to be 12-2-2 at least that is how HD called it. Had to get paint and checked on it while looking at dimmers, 12-3 was priced at 1.07 while 12-2-2 was 1.08 per foot cut. The 12-2-2 had a yellow tag usually clearance.
Edited 2/29/2008 11:36 am ET by wallyoEdited 2/29/2008 11:39 am ET by wallyo
Edited 2/29/2008 1:27 pm ET by wallyo
Hot tub wiring has a bunch of special requirments such as requiring insulated ground wire, if outside. I have not sure of all of the details off hand.But for the most common packaged hot tubs it is not that difficult. They could have issued a cheatsheet like many building offices do for decks.But if you are putting one to gether (separate pumsps, heaters, lights) and/or with a pool then you can get into a lot of very tricky areas.BTW, there are 2 different 12-4's. One is 3 "hots" or switched and 1 neutral. The there is a pair of hot/neutrals as you described.The 3+1 might save a very, very small amount of copper, It can be used for things like a 3/4 way switches where you want to run the the circuit through several lights or if you want both switched and unswitched power at the far end. And the 2+2 only might have a very minor saving in cost for things like kitches where you want to have alternating receptacles and would have run 12-3 if it wasn't for the GFCI's.It can also be used where a multi-wrie circuit would have been used in the past for multiple bedrooms. AFCI's won't work with shared neutrals. They have a GFCI like feature, but is set to trip at 30 ma unbalanced currents which is too high for human protection. It's purpose is to detect deteriating insulation.But for either case the the only place that it might be cost effective is if it is a tract builder and have everything planned out to the penny in cost. Otherwise is not worth it to get the extra type of cables." The part I cannot remember is I think he made us put a tie across the two breaker handles in effect making it a 240 breaker."I have to look up the exact wording and they keep changing it.BUT IIRC the concept is that if you have a 240 load on the circuit then you need a common trip breaker (ie, 2 pole). If you have a single device with both legs on it then you need can use a 2 breakers with an approved tie bar. It some areas (and until recently the code in Canada) it used to be common practice to break the tab on the receptacles and wire on half of the duplex to one leg and the other leg to the half. With a tie bar when you manually tripped the breaker you would get both. But an overload may or may not trip both legs.If both legs did not land on the same device you could use 2 separate breakers..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
That might be why he had us tie the breakers, ie we split the outlets with the side tab that way if one was working on the outlet one whould be sure to turn power off to the top and bottom outlets. But still need to check if I did it, I just remember him bring it up.Wallyolook at my edit you may have missed itThanks
Just to clarify a little further over some of your concerns. I intend to connect the two hot leads from the 12-3 to a 20 amp double pole breaker and not two single pole breakers as you probably assumed from the poor wording of my original question. I also have no need, nor am I planning to connect to the load terminals in either receptacle.
Thanks guys for your help and your quick responses. I really appreciate it.
Paul
Edited 3/2/2008 10:27 pm ET by Flips
Since the "load" is coming from downstream of the GFI it's not going to know if it is a "shared" neutral or not.
The neutrals back in the panel are all tied together on the neutral bar.
“The world is a dangerous place, not because of those who do evil, but because of those who look on and do nothing.” —Albert Einstein