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funfool 11-29-2012 09:13 PM

reasons for a gfi to trip?
Working on a laundry room remodel, currently has a gfi for the washer.
It has a 20 amp circuit feeding a junction box, from that box feeds a total of 2 ceiling lights, the washer gfi, and a new outlet into a hallway that probably will never be used except for a night light or something.

Gets a little trickier because is actually two hots going into the junction box.
Problem is, if I connect the gfi correctly to line side, then run the other outlet in hallway on load side, trips the gfi.
My first thought was a bad gfi and replaced. Does same thing.
Now I am thinking that with 2 power feeds coming into J-box, if neutrals were tied in together, would this cause the gfi to trip like this?
Works fine on line side, just trips when adding a load to it.

Is a confusing mess inside the j-box and not sure if the neutrals are tied together ... think big blue wire nuts.
Just my best guess at this time.
Just wondering what else would cause this ... the gfi as is, has worked for the washing machine for years.

joecaption 11-29-2012 09:16 PM

Can not have a shared nutral on a GFI.

Stubbie 11-29-2012 09:31 PM

1 Attachment(s)
Sounds like you have a multi wire branch circuit with shared neutral. You cannot protect any receptacles on the load terminals of a gfci when running a MWBC. The down stream receptacle must be another gfci connected to its line terminals

Kinda like this

AllanJ 11-29-2012 10:01 PM

To continue GFCI protection from the load terminals of a GFCI receptacle unit you need a separate 2 wire cable not connected to any other incoming hots or neutrals in the box.

Everything connected to the load terminals of a GFCI unit is a subcircuit unto itself.

funfool 11-29-2012 10:49 PM

Is all I could think of that makes sense ...
Really is not part of my job and would now be a change order to correct the issue.

Now wondering if is worth the cost of repair.
Who ever did it 22 years ago, used a under sized box. and I would have to tear it out and use proper sized box, once opened up who knows how much more will need to be done.

Is a shared neutral really that bad, been this way for 20 years?
I dunno and why asking.

I know I can walk into many homes and start picking out code violations and or things that need repaired, next thing you know we bulldoze the house and build a new one.
Is an old house built in the '50s and been upgraded several times.
Am I crying wolf to say this needs to be fixed?

AllanJ 11-30-2012 06:23 AM

A shared neutral is not necessarily bad but, the hot and neutral emanating from the load terminals of a GFCI unit cannot be commingled with a hot or neutral in the feed from anywhere else.

So for each cable continuing downstream from the box with the new GFCI you have the choice of: (1)_make it part of the GFCI protected (load terminal) continuation or (2) make it the raw power (unprotected) continuation.

While a GFCI receptacle counts the same two points of box fill as an ordinary receptacle, the GFCI is somewhat larger and can force the issue regarding replacing the box with a larger one, whether or not you use the load terminals.

When installing the GFCI I would not put in larger boxes at locations along the circuit that are not being modified or disturbed. Nor would I put in a larger box at a location that gets nothing but a new regular receptacle unit.

A "laundry room remodel" will require a new 20 amp circuit directly back to the panel with receptacle(s)* only in the laundry area and no other loads such as fans or lights, if such a dedicated circuit is not already there. Existing circuits do not have to be removed or modified just because of this.

* A minimum of one "round" 20 amp single or two "round" 15 amp singles or one duplex.

funfool 11-30-2012 08:43 AM

I feel better about the neutral now. I thought that was the issue, I have just never wired anything in that fashion and ran into the problem.
We considered bringing in the electrician for this job, is pretty small and he cant get to it till next week.
I basically just left everything as is except for one wire.

This a old garage apartment conversion, there is two 15 amp circuits for plugs and lighting, the 1 20 amp that used to be for kitchen.
Several years ago stove and fridge was removed and replaced with washer and dryer.
Still looks like a kitchen with a washer and dryer in it.
I removed an old pantry, kitchen sink and cabinets, built closet for washer and dryer, looks like a laundry room now.

The 20 amp breaker was running gas stove, fridge, range vent.
I extended the fridge outlet and moved it to hallway.
The gfi for washer stays as is.
I found the hot wire for the old range vent, they wire nutted it and stuffed it in the wall and patched over it.
I put it in a J-box and used it to feed the light for the closet.
Not exactly code, but close for a old garage been remodeled 3 times.

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