GFI Keeps Tripping

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Old 07-10-10, 04:43 PM
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GFI Keeps Tripping

I installed a GFI at sink counter top to bring to code. The wire is romex 20 amp #12 on 20 amp breaker.The existing wire in box are all two wire.Hot, netural, and ground.There are three sets of two wire.I found the line wire...hot to line , netural to line. My other to sets are my load.The load going over to refrig and microwave work fine does not trip gfi.(Yes I know these two shuold be dedicated circuits to refrig and micro and will be.)My other load goes across counter top that feeds ( I will call it recep A) Recep A goes under the sink and feeds ( I will call it recep B) Recep B the top of recep is hot all the time power coming from recep A. The bottom of recep B (with tab broke off) the power comes from a differant circuit.Bottom of recep B power comes from switch at sink to control garbage disposal.This switch also controls a small light at sink.If I change the load to line going across counter every thing works but is not GFI protected.
 
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Old 07-10-10, 05:14 PM
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You have a fault somwhere on the load side, but I guess you know that. I'd suggest pulling the recptacles on the load side and find the fault. It could be something as simple as a ground wire touching a neutral screw on a receptacle. That won't trip a circuit breaker, but it will trip a GFI. Also, the receptacle under the sink that is fed by two circuits is suspect. The neutral from the other circuit being combined with the neutral of the circuit with the GFI may be causing you a problem.

The bottom of recep B (with tab broke off) the power comes from a differant circuit
It's a little unusual to have two separate circuits on one duplex receptacle. I'd disconnect the circuit with the GFI here and wire nut the ends of the wires and leave them in the box.
 
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Old 07-10-10, 07:21 PM
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switch loop and shared neutral

if you turn off power to countertop and the garbage disposal receptacle under the counter ( so that the duplex is dead both upper and lower part of it ), and pull out the receptacle to see the wiring, what comes in and out of the junction box and what goes where?
 
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Old 07-10-10, 07:51 PM
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possible shared netural....

In recep B bottom of recep is switch leg for garbage disposal. Recep B top is always hot coming off of recep A. The switch at counter on own circuit is the type where they are stacked on top of each (not a single pole) In this switch I have two sets of two wire and one three wire. One leg to light, other to disposal,one is feed the other not sure...........
 
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Old 07-10-10, 08:34 PM
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if you pull out the bottom receptacle, does it have 2 12-2s coming in? as what concerns me is where the GD side of receptacle b is getting the neutral from...

http://3.bp.blogspot.com/_NM3caZ-c5A...h+light+gd.jpg


check the drawing and see if i got your set up correctly
 

Last edited by mikerios; 07-10-10 at 09:03 PM.
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Old 07-11-10, 07:03 PM
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recep B has two 12-2.......

Mikerios....thank you for your help.....what an awsome drawing this is close to my set up.The 12-3 red is on the left of switch.This is probably the switch leg for light.There are no red legs in Recep B.Recep B has two 12-2.I believe you are on the right track as to where recep B is getting the netural from.I think a solution would be install separate gfi on recep B (garbage disposal)on load side.Install separate recep off of A with tab on (I will call this Recep C) Recep A an recep C would be gfi protected.
 
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Old 07-12-10, 05:57 PM
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seperate

then i would think thew solution would be to separate the neutrals at the recept B,

as if you got 2 - 12/2 coming in one from the GFCI, the other from
the upper switch box, if both of them are landed on the recept B, then the neutral tab needs to be broken off

as that's why the GFCI trips, it sees the return on the neutral from the other circuit and sees that as a current leak.
 
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Old 07-14-10, 04:35 PM
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apbrooks,frenchy, second opinion....

Originally Posted by mikerios View Post
then i would think thew solution would be to separate the neutrals at the recept B, .
Thanks mikerios I have never heard, nor did this and not sure if safe practice. Can other moderaters help me out here for your input apbrooks,frenchy,chancler what do ya' say
 
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Old 07-21-10, 09:33 PM
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That is little unuseal set up you have there and I did not catch one part if you mention or not did you have dishwasher there as well ??

The reason why you keep the netural seperated due the GFCI will sense unbalnced netural or hot side and it will trip pretty fast.

Normally I set the Dishwasher and Garbage dispoal on it own circuit if possible { of course mantory for new home set up }.

Merci.
Marc
 
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Old 07-24-10, 08:07 AM
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disposal only...

Originally Posted by french277V View Post
That is little unusual set up you have there and I did not catch one part if you mention or not did you have dishwasher there as well ??
It is a weird set up yes......there is no dishwasher in kitchen.
 
 

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