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GFCI breaker tripping

I

Inspector 102

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Joined
Oct 22, 2009
Messages
371
Location
N/E Indiana
A detached garage was sub-fed from the home with 4-wire assembly to a subpanel. Neutrals and grounds were isolated in the subpanel with the grounding bar kit bonded to the enclosure through the bonding screw. The homeowner installed 2- GFCi breakers to protect the general purpose receptacles and immediately the breakers trip with no load on them. A regular breaker was installed and no tripping. The homeowner wants the breaker instead of receptacles, but as the inspector, I have no clue what is wrong with this installation that is causing the tripping. Any thoughts?
 
There can be many things wrong with this install. First is it a MWBC? If it is then 2 sp gfci breakers will not work and will always trip. My other guess is a neutral to ground short. It is very suspicious that both circuits don't work. Something is wired incorrectly for sure.
 
Dennis, with no load, i.e. nothing plugged in, would a neutral to ground short trip a breaker?
 
Last edited by a moderator:
I guess I should have said that I know it will. I have tripped gfci circuits when changing a light and the neutral and ground touched.
 
The first thing wrong is that in a detached garage the panel needs to be installed as a main panel not a sub. Complete with it's own GEC. If it were an attached garage it would be set up as a sub panel and the enclosure would not be bonded
 
fiddler said:
The first thing wrong is that in a detached garage the panel needs to be installed as a main panel not a sub. Complete with it's own GEC. If it were an attached garage it would be set up as a sub panel and the enclosure would not be bonded
Click to expand...
I believe the OP has it correct. The neutral is isolated and the ground bar is attached or bonded to the can. The GEC is connected to the equipment ground bar not the neutral.

What you are saying is not quite correct. A detached garage needs 4 wires as of the 2008 NEC and the neutral and grounds are isolated. The difference is the gec gets connected only to the ground bar. The detached garage is really a sub panel with a grounding electrode added to it.

Even if the bonding where incorrect it should not affect the gfci.
 
Inspector 102 said:
A detached garage was sub-fed from the home with 4-wire assembly to a subpanel. Neutrals and grounds were isolated in the subpanel with the grounding bar kit bonded to the enclosure through the bonding screw. The homeowner installed 2- GFCi breakers to protect the general purpose receptacles and immediately the breakers trip with no load on them. A regular breaker was installed and no tripping. The homeowner wants the breaker instead of receptacles, but as the inspector, I have no clue what is wrong with this installation that is causing the tripping. Any thoughts?
Click to expand...
Were you able to find out what was causing the problem?
 
$ $

From Mike Holt's Forum:

Inspector 102 states:



"The culprit was finally found in a factory wired cord & plug connection to afluorescent light fixture that was plugged in.........I looked at everything field installed

and found no issues and it still had me stumped. Homeowner finally said he had plugged

lights in and never thought it would be the issue.........Wire connector had nicked the

neutral wire and allowed grounding to the fixture itself........Why is it always the little

things that trip us every time......Thanks for all the advice."
Click to expand...
$ $
 
Thank you Northstar for posting for the other site, forgot to update this one. The homeowner only had 1 GFCI, but tried a second one. It was not 2 separate circuits. Definitely a new one on me. Never had anyone have problems, and was not sure if it was the 4 wire and ground rods installed possibly creating the problem. The homeowner was happy it was not the work he did and it was sent from the factory or move around enough to create a fray on the whip to cause the fault. Breaker doing its job very well.
 
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