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#203426 - 09/28/11 01:31 PM Best method/tester for Earth Ground Resistance
PE&Master Offline
Member
Registered: 02/25/06
Posts: 138
Loc: TX, USA
I've got a municipal project that needs to have the earth ground resistance measured using the fall-of-potential method.

From what i can determine this takes a meter with a couple of probes to stick in the ground at specific distances from the ground ring. Aside from that type of device (like a Fluke 1625), they make a earth ground tester that is a clamp on tester. I realize that the clamp on testor won't give me a fall-in-potential measurement but is there a major difference in the two types of testors?



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#203429 - 09/28/11 03:08 PM Re: Best method/tester for Earth Ground Resistance [Re: PE&Master]
Tesla Offline
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Registered: 06/16/04
Posts: 1273
Loc: Sacramento, CA
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Tesla
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#203430 - 09/28/11 05:52 PM Re: Best method/tester for Earth Ground Resistance [Re: PE&Master]
HotLine1 Offline


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Registered: 04/03/02
Posts: 6776
Loc: Brick, NJ USA
Tesla:

Thanks for the nice informational link!!!
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#203432 - 09/28/11 06:58 PM Re: Best method/tester for Earth Ground Resistance [Re: PE&Master]
KJay Offline
Member
Registered: 11/27/07
Posts: 763
Loc: MA, USA
I looked into getting one of the clamp on ground testers a few years back, but after I read up on them, I wasn’t confident about the accuracy or if it would do what was needed, so I opted for a traditional 3-point tester kit instead. They may have made improvements to them since then though.
The Tech Tips pdf below sort of hits on some of the things I was reading about back then.

Clamp on Method
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#203440 - 09/29/11 11:08 AM Re: Best method/tester for Earth Ground Resistance [Re: HotLine1]
PE&Master Offline
Member
Registered: 02/25/06
Posts: 138
Loc: TX, USA
Great article on the diffences.

I've decided to rent the Fluke 1625 for a couple hundred bucks.
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#203471 - 10/01/11 05:50 PM Re: Best method/tester for Earth Ground Resistance [Re: PE&Master]
nesparky Offline
Member
Registered: 06/21/01
Posts: 642
Loc: omaha,ne
It's been a while since I have been here, Just completed aroject where every building had to have the grounds tested. We used an EXTECH 3 point ground tester. Cost for a new one is about $180.00
Not as fancy or as capable as the fluke referenced above but good enough to test grounding before power is applied. The model we used instructions said not to be used if voltage tested above 10 volts
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ed
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#203476 - 10/02/11 03:55 PM Re: Best method/tester for Earth Ground Resistance [Re: PE&Master]
mikethebull Offline
Member
Registered: 03/18/07
Posts: 100
Loc: Rhode Island
I used that EXTECH 3 point meter on a distribution system for a eye glass manufacturer the equipment purchased was from Germany. That meter worked really well.
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