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GFI question

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USA, CA, Residential, 120VAC -
On my GFI outlets....
When I have the power off, should Neutral to Ground read "open".?
I thought it should read "short", but maybe a GFI is different.?
Thank You
 
In the US the Neutral and Ground are tied together at the entry circuit breaker panel. Therefore if I look at the power coming into an outlet and measure the white wire (neutral) to the green or bare copper wire (ground) I should read about zero ohms or yes, pretty much a short for all intensive purposes. Between the black (hot) and white (neutral) or the bare wire (ground) I should read about 120 VAC.

While a GFCI outlet of circuit breaker includes a ground wire it is not necessary for normal GFCI operation. I am not sure what you are asking.

Ron
 
Neutral and Ground should only connect at the main panel. A GFI outlet by its self will not have then connected together.

Neutral and Ground will not connect if the "switch" breaks both power and neutral. Not likely.
Many old houses do not have ground wires in the wall. They may have 3-prong plugs, installed years later, and the ground is not connected.

By "power off" did you pop the GFI? or did you turn off a switch?
 
Again.....sorry.....should have been more clear.
GFI. 1988 build, 3 wire home.
Power Off at the panel (circuit breaker)
Ground to Neutral.
DMM Says OL.
Is that right.?
Thank You
 
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Nope. Ground to neutral should be about zero ohms as they are tied at the mains entry (power panel). I would suggest an open ground if the outlet was working.

Ron
 
Well......My Greenlee GT-10 says open ground.
Does that mean No Ground.?
And yes, I can run a vacuum cleaner from the GFI.
I can measure Ground of the GFI to Ground of a good receptacle and see what that says.
 
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2 story house.
There is 1 GFI receptacle (with the red button and black button) in the Master Bath. It reads Open Ground. Receptacle in the other upstairs bath reads the same.
Down stairs, bathroom receptacle reads Open Ground. Receptacle in garage reads Open Ground.
There is another GFI receptacle (red button and a black button) in the Kitchen and that reads Normal.
BTW just to make sure, I plugged an extension cord into a good outlet in the master bedroom. The ground on that extension cord reads OL, on a DMM, to Ground of the Master bath GFI.
 
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1) If you look at a GFCI, there is no way that the GFCI could open the ground.

2) It is permissible to install a GFCI on an ungrounded circuit provided it is marked as such "No protective ground".

3) Some testers will get confused. My expensive >$200 Ideal SureTest said I had reverse polarity, when, in fact, the ground was open, but it also indicated a high ground resistance of > 16 ohms or so.
It got the ground right, but the reversed polarity wrong. The ground was likely picked up through the shield of an antenna coax to the ground block some 40 feet away.
 
Then I would say for the outlets in question the ground is open.

Ron
 
Then I would say for the outlets in question the ground is open.

Ron
No doubt.

So how do I troubleshoot this.?
Pull one of the receptacles, remove the Ground wire from it, and measure that Ground wire to a known ground.?

I guess what I am wondering.....How in the Heck is this possible.?
Could this have "happened" somehow during the life of a 1988 home.?
Is it more likely it has been this way from the beginning.?
Anybody want to take a guess.?
Thanks
 
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If I had to guess I would say there is a possibility it has been that way since day one. I would pull the receptacle and start inspecting the wiring. If a series of recepticals are on the same line there is a possibility at some point in that path the ground was omitted or broken. Things like this can be annoying as we can't see inside the walls. ;(

Ron
 
In my case, I believe that the wire nuts and twists were not installed correctly. I haven't fixed it yet, but I disconnected everything downstream from the bad ground. I know the box with the problem.

Remember that in a metal electrical box, the box AND the outlet have to be connected to ground. You generally cannot rely on the screw on the outlet to make the connection (there are special outlets where you can). Probably they are twisted, but not making intimate contact because the nut was installed incorrectly or the wrong size was used.
 
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