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Swansea, IL
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Sagamore Hills, Ohio
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 GFCI Question
[#2] Posted: 06/16/2010 - 3:45:41 PM |  |  |
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How old is the house Mark?
Is it a true grounded system (bootleg grounds ruled out)?
If the outlet has reversed polaity those three light testers will show it when first plugged in.
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Terry
http://www.hlis.net
This space for let - please inquire within.
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Portland, OR
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GFCI Question
[#3] Posted: 06/16/2010 - 3:53:48 PM | | |
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Testers always do that when "trying" to cause a ground fault so I don't think it means you have a problem. All of the GFI outlet (and likely breaker) manufacturers specify the only true way to test is with the 'test' button on their equipment. As long as that works it's fine.
I would never have found what you describe since I stopped carrying the 3 prong tester with a GFI test button for this exact reason.... and I got sick of moving mountains of stored items to reset the GFI I tripped.
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Swansea, IL
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GFCI Question
[#4] Posted: 06/16/2010 - 3:59:56 PM | | |
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House built in 1947. Updated panel maybe 10 years old. I did not pull the outlets to rule out false grounds, but that is a good point. It there were a bootleg ground then the tester would not work in tripping the GFCI breaker.
The more I think about it - I like the false ground idea. Makes sense for now. I'll sleep on it and decide how to write it up in the morning.
Thanks Terry
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Mark A. Perry
www.ahis1.com
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Sagamore Hills, Ohio
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GFCI Question
[#5] Posted: 06/16/2010 - 4:20:15 PM | | |
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Although rather costly I always use this tool on older homes with 3-prong outlets -
http://www.professionalequipme...testers/
as it will call out a false ground.
Only reason I picked Professional Equipment was the ease in finding the tool. I'm sure they can be found elsewhere at a better price.
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Terry
http://www.hlis.net
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Philly, PA
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GFCI Question
[#6] Posted: 06/16/2010 - 4:22:13 PM | | |
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It would still trip with the tester with a bootleg ground. Did you test your tester on any other GFCI recepts? They have a habit of dying. Did you happen to check whether power to the kitchen receptacles was actually cut off when you tripped the breaker (maybe mislabeled?)
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Swansea, IL
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Sagamore Hills, Ohio
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Rochester, New York
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Lafayette, Louisiana
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GFCI Question
[#10] Posted: 06/17/2010 - 05:54:08 AM | | |
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For the record, can someone describe 'bootleg ground' and 'false ground'? The only terms I'm certaqin of are 'grounding connection present' and 'grounding connection not present'.
Marc
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"If Guam gets too overpopulated, it might tip over."
Congressman Hank Johnson (D) GA |
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Philly, PA
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GFCI Question
[#11] Posted: 06/17/2010 - 06:14:37 AM | | |
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Marc, they are talking about a jumper from the neutral terminal to the grounding terminal in the outlet so it tests as grounded but isn't.
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Philly, PA
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GFCI Question
[#12] Posted: 06/17/2010 - 09:27:53 AM | | |
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Quote: Originally posted by Chad FabryQuote: I've never run into a GFCI breaker or outlet that was on a false ground circuit so I've never had the opportunity to test first hand. If the tester creates a fault or imbalance by shunting some of the current to a ground then it won't trip the GFCI if there's a false ground. The circuit remains balanced; the diverted current is still following its intended path.
Makes sense. If a GFCI receptacle has a bootleg ground the tester will trip it but if the GFCI is downstream, the tester wont trip at a regular receptacle upstream with bootleg ground (as in Jim's scenario).
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Lexington, KY
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Lafayette, Louisiana
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GFCI Question
[#14] Posted: 06/17/2010 - 11:37:28 AM | | |
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Got it. Thanks.
Marc
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"If Guam gets too overpopulated, it might tip over."
Congressman Hank Johnson (D) GA |
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Sagamore Hills, Ohio
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GFCI Question
[#15] Posted: 06/17/2010 - 12:04:14 PM | | |
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Quote: Originally posted by Richard SaundersQuote: Originally posted by Chad FabryQuote: I've never run into a GFCI breaker or outlet that was on a false ground circuit so I've never had the opportunity to test first hand. If the tester creates a fault or imbalance by shunting some of the current to a ground then it won't trip the GFCI if there's a false ground. The circuit remains balanced; the diverted current is still following its intended path. Makes sense. If a GFCI receptacle has a bootleg ground the tester will trip it but if the GFCI is downstream, the tester wont trip at a regular receptacle upstream with bootleg ground (as in Jim's scenario).
No the tester shouldn't trip it in either case.
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Terry
http://www.hlis.net
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Philly, PA
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GFCI Question
[#16] Posted: 06/17/2010 - 12:39:09 PM | | |
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It will trip if the GFCI has a bootleg ground. Try it yourself.
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Sagamore Hills, Ohio
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Philly, PA
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GFCI Question
[#18] Posted: 06/17/2010 - 7:06:21 PM | | |
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Terry, as I know you know, the tester shunts a bit of current from the hot to ground, un-equalizing the load and tripping the GFCI. With the downstream GFCI, this wouldn't be "noticed" by the circuit in the downstream GFCI breaker because with the bootleg ground you have the same current through the neutral as before pushing the test button. But, at the actual receptacle you are testing, the GFCI circuit is upstream from the bonded neutral and ground, the circuit "notices" that some current has been shunted away from the neutral.
Like Chad said, there's no imbalance downstream, only at the actual receptacle.
Don't know if I explained that well, I didn't "get" it until I read Chad's post.
I think you could build a device to check for bootleg grounds using your tester and a plug-in GFCI receptacle but it makes my head hurt to figure out how to wire it.
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Portland, OR
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GFCI Question
[#19] Posted: 06/17/2010 - 10:12:57 PM | | |
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Keep in mind there are plenty of other ways to "boot leg" a ground aside from the neutral to ground jumper at the outlet. Most of which we would rarely find.
You could bond an outlet to a co-ax cable box and likely get a decent ground reading.... it doesn't mean it's a good or correct ground.
How many times have you been in an old basement or crawl space and seen a 70 year old ground clamp on a water pipe? Again, wrong but will light the three prong tester in question to read "correct".
Personally, I consider the "grounded" readings I get at the outlets compared to the number or ground wires I see at the panel to get a general idea of what's going on. When I get suspicous I'll pull a few outlets to look for the ground to neutral jumper which often pops up when things aren't adding up.
One thing I know for sure.... I'll never find every incorrectly grounded/bonded outlet in an older house and make no claim to.
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