James Wilkinson Sword wrote:
On Thu, 05 Jan 2017 01:13:23 -0000, Dean Hoffman
wrote:

On 1/4/17 6:32 PM, James Wilkinson Sword wrote:

Some cut.

I guess one doesn't test earth grounding with a regular ohm
meter.

You guess?

The instructor at one of my code refresher classes asked once if
anyone had
the correct type of tester. No one did out of at least 50
electricians. Earth grounding
is primarily for damage from lightning. He also had a diagram showing
how little current would flow through the earth if a well motor had a
short to the frame. The resistance was so high that there was no way
even a tiny fuse would blow if there was a short.
This is from the meter maker Fluke:
http://support.fluke.com/find-sales/Download/Asset/2633834_6115_ENG_A_W.PDF



"A good grounding resistance is 5 ohms or less" - well since I got 20
MOhms, I guess that isn't grounded.

So did you use an actual ground tester or a volt/ohm meter? It
sure seems odd that
your results don't match Mr. Ufer's and bunches of people after him.
An article in Electrical Contractor magazine says Ufer's grounding
electrodes kept the resistance at 2-5 ohms over a 20 year period.
http://www.ecmag.com/section/codes-standards/what-ufer-ground

Resistance is resistance. Concrete does NOT conduct. WATER conducts.

Not that well, it is whatever salts and impurities in it that do.



Concrete is a porous material which may or may not contain water. The
floor of your house should never contain water, or you have BIG
problems, way above a possibility of shock.