I have just installed two 20amp small appliance circuits in my kitchen (remodeling).
I used 12/3 wire and alternated the receptacles between the two circuits.
The first recep. on each line has a GFCI which then feeds through to it’s respective receptacles down stream.
Here’s the problem:
When I turn on the circuits independently of each other they work fine (I’m testing with one of the yellow plugs ins with the three lights), but when I turn both circuits on together I get an assortment of reversed hot/neutral lights, and in one case all three lights come on.
Obviously I’m missing something but can’t figure it out–does anyone have any trouble shooting suggestions or solutions that come to mind.
Thanks
cje
Replies
If I am reading this right you have 2 gfci's in parellel on the same neutral?
I know gfci's don't like load sharing but I have never seen them used in this way, nor have I seen a diagram like this in the instructions. Is this an approved method?
My guess is you should have feed the circuits seperately with 12/2 and put a gfci at the head end . Maybe try taking the second gfci out of the circuit to prove my theory?
A GFCI works by compare the current in the hot lead with that in the neutral lead. Normally they are the same, but not with a ground fault.
When you run a circuit with a shared neutral then the current in the neutral will not be the same because of the 2nd hot.
You have several choices.
1) At the first box convert it to 2 runs of 12-2.
2) Don't feed downstream outlets, but install a GFCI at each outlet.
3) Replace the breaker(s) with a 240 volt GFCI breaker. At that point is compares the difference between the two hots and the neutral as they all go through the same device.
DON'T SHARE THE NEUTRAL WITH GFIs!!
When one GFI is tripped, its neutral will still be energized by any device that is using current on the other GFI.
This is an unsafe use of a device that is designed to break the exposure to current when tripped. You are by-passing that protection with the shared neutral.
Replace all of the outlets in each string with GFIs or run a dedicated neutral for each of your two down-stream outlet strings.
"Replace all the outlets in each string with GFIs or run a dedicated neutral for each of your downstream outlet strings..."
Hi Norm. Got a question for you. Bill Hartman made the suggestion to simply replace the breaker in the panel box with a 240 volt dedicated GFCI breaker. If such breaker was installed, and the 2 GFCI outlets replaced with regular outlets instead, would not this situation suffice? Please tell me what would be wrong with this set-up?
I must be missing something here, but at first glance it seems easier to replace 2 receptacles and change out the breaker, than to rewire all outlets accordingly. What am I not seeing?
Thanks.
Davo
I see only 2 problems. All your outlets will trip off in the event of a fault, and you will have to go to the panel to reset. Here is a link from Square D.
http://www.squared.com/us/products/circuitb.nsf/07a0210021262d45862564b5006e4f84/b24326ebd2d78eb485256a1b00622276/$FILE/48840-435m530.pdf
Yes, Mark you're right. If the GFCI breaker tripped, all downstream outlets on this circuit would be dead and you would have to reset the tripped breaker at the panel box (after first figuring out what caused the breaker to trip in the first place.).
I don't consider this a "problem," but rather pretty normal (That's what breakers and panel boxes are all about), and at worst, inconvenient (having to walk to panel box to reset). But, perhaps I'm still missing something here.
Davo
Both legs of the circuit will trip if you have a 220 volt GFCI breaker, which makes it a bit harder to locate the fault since there are more locations to check. I did not mean to say "downstream" outlets.
The only other thing I didn't mention is that the breaker is relatively expensive, but it probably is higher quality than the usual GFCI outlets. Other than that, you're not missing anything.
Edited 10/13/2002 7:59:21 PM ET by MARKH128
Thanks Mark.
Yes, those type of breakers do indeed cost a few bucks!
Davo
The big difference between GFCI's and normal breakers is that GFCI's are extremely sensitive, and trip far more often. That's why you want to have them in the same room with everything they control.
I've turned ordinary breakers off to work on something, but I can't remember having to go to a panel and re-set a tripped one in the last 20 - 30 years. With some GFCI's you can drink hot tea and exhale on them, and they'll trip. Expect to be re-setting them several times a year.
-- J.S.
Wouldn't a 240V GFCI be comparing the current in the two hots? If you've actually got it wired as two 120's with a shared neutral, the current in the two hots will almost never be equal.
In my town running 12/3 with 20 amp gfi on kictern counter is a code violation. I know I got wrote up on it, 12/2 only legal way
"Wouldn't a 240V GFCI be comparing the current in the two hots? If you've actually got it wired as two 120's with a shared neutral, the current in the two hots will almost never be equal."
No GFCI breakers are different. They have a pigtail on then that connects to neutral buss bar and then another terminal for the load neutral. That way the neutral current and the hot (120) or both not legs (240) current all goes throught them to be summed to see if there is any current that is going to a ground path.
Not an electrician by trade so correct me if I am wrong....I thought that it was against code to run two seperate breakers in the manner posted (common neutral). I believe the breaker must be a 240 volt type where both sides trip together and cannot be turned on or off seperately ?
Bill Koustenis
Edited 10/13/2002 6:33:33 PM ET by Mr Bill
I have left some comfusion with my comments about both 120 and 240 GFCI breakers. I was talking about general applications and not this specfic problem.
As far as the GFCI for this application (dual circuits with a shared neutral) then a 240 GFCI is needed as you have to have on common point where all both hots and the neutral feed from to measure the current differences.
But about breakers;
"Not an electrician by trade so correct me if I am wrong....I thought that it was against code to run two seperate breakers in the manner posted (common neutral). I believe the breaker must be a 240 volt type where both sides trip together and cannot be turned on or off seperately ?"
That is true only if you have 240 volt loads. If you have two sets of 120 volt loads then they can be separate breakers.
But that brings up the two complaints that people have with those circuits.
1) You think that the circuit is off as that outlet is dead, but there are wires in the box from the other leg that are still hot.
2) being on two different breakers someone can move one of the connections so that they are on the same leg.
But that brings up the two complaints that people have with those circuits.
1) You think that the circuit is off as that outlet is dead, but there are wires in the box from the other leg that are still hot.
2) being on two different breakers someone can move one of the connections so that they are on the same leg.
To your comments I would add another potential problem, related to 1) above. If someone were to shut down one circuit breaker and not the other and then disconnect the neutral (say, in a box where the hots separate), then the disconnected neutral is no longer grounded and will be hot. Perhaps an electrician would be tipped off by the presence of a red conductor and look into it more carefully first, but I suppose anyone could get taken by surprise by that hot white wire.Be seeing you...
Just another reason to avoid using 12-3 instead of 12-2. Not worth the bother to me.
thanks for the advice- will be replacing downstream receps. with GFCI tonight.
good point about 12/3
cje