On 1/4/17 2:00 PM, James Wilkinson Sword wrote:

It was more about getting an electric shock by standing on the floor
of your house while touching something live. This was suggested by
someone recently as being a danger. I just measured some concrete
to make sure I wasn't being ignorant, and it was off the scale
(20MOhms)

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