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?
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.
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