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Old 08-17-2011, 09:53 PM   #1
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Tripping GFIs


I have an outside GFI that trips--sometimes overnight, sometimes after a couple of weeks, sometimes when its wet and sometimes dry, ... I've been trying to diagnose this problem and have separated the wires downstream of the GFI into sections one at a time to try to isolate the section that causes the issue.

In the process of doing this, I began testing the buried wiring to see if I could find anything wrong with the sections. I found that I had some continuity (not much, but some) between hot & ground. There wasn't anything else attached to the wire (no outlet, switch, light, etc). One end had 3 ends all separated and in the air and I was testing from the other end. It was simply a buried piece of underground rated wiring that had some continuity between two of the conductors.

Could the wire itself be bad? Is what I'm doing somehow causing false readings? I have some other examples that are equally strange that I cannot explain.

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Old 08-17-2011, 10:15 PM   #2
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Tripping GFIs


Sounds like the wire/cable is nicked/damaged.

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Old 08-17-2011, 10:26 PM   #3
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Tripping GFIs


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Sounds like the wire/cable is nicked/damaged.
So here's another one, that's even stranger--I'll call it Case 2.

I have an underground rated wire buried for ~120 feet and sticking out of the ground at the other end. I have detached that end from the outlet it was attached to and the conductors are separated and in the air.

I disconnected the other end of the wire at the next upstream junction box such that there are six conductors separated and in the air. Three of the conductors come from the panel and the other three are the other end of the buried wire referenced above.

In the process, I check continuity between conductors and find there is continuity (5K ohms) between the ground from the panel and the hot from the buried section. I also find there is continuity (10K ohms) between the ground from the panel and the ground from the buried section.

How in the world can this be the case? Is what I'm doing somehow fatally flawed? The should be a COMPLETE open, right?
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Old 08-17-2011, 11:28 PM   #4
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Tripping GFIs


insulation is not perfect, only good enough to 'hold in' the rated voltages, but 5 and 10k ohms is quite low, but not a direct short. i would want to think there is a cut in the buried section..
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Old 08-17-2011, 11:36 PM   #5
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Tripping GFIs


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insulation is not perfect, only good enough to 'hold in' the rated voltages, but 5 and 10k ohms is quite low, but not a direct short. i would want to think there is a cut in the buried section..
That would sound logical but let me repeat what I'm testing. I'm testing the continuity across the ground conductor in a wire that leads to the panel with a hot (and then ground) for a COMPLETELY SEPARATE and UNATTACHED wire that goes through the ground ~120'...and finding there is only 5-10K between the two. How can there be any continuity between the two? Am I missing something?
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Old 08-18-2011, 07:36 AM   #6
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Tripping GFIs


All you would need would be a nick in the insulation and for moisture in the ground to bridge the gap to provide continuity.
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Old 08-18-2011, 08:44 AM   #7
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Tripping GFIs


My dad had a similar problem with a buried cable------His power bill nearly doubled----

That's what started the search going-----Much cheaper to just replace that run of cable.
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Old 08-18-2011, 12:43 PM   #8
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Tripping GFIs


Are you touching the leads of the meter when you measure continuity? Your fingers may have 5-10K resistance, if they're slightly damp.

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