Just as a point of reference, last time I checked the driven galvanized pipe that is my electrode at the service panel [from 1935?] reads about 65 ohms with the plumbing/water-pipe bond isolated, but the steel casing on the water well with static water at around 70 feet measures about 2 ohms using a conventional Biddle “3-lead”/fall-of-potential test set.
There is a 1970 paper ieee-pcic.org/archive/fagan_lee_paper.pdf that is sort of a followup to George Ufer’s earlier work.
At a new public-school building once, a contractor wanted a test on a driven rod, which measured about 22 ohms. He thought that may be ‘too close’ to 25 ohms and likely the inspector would accuse him of “fudging the numbers,” so he used a bucket of water to soak the two test electrodes. Then, he blew a gasket when the retest reading increased to about 23 ohms(!)
[This message has been edited by Bjarney (edited 06-20-2004).]
