SQLit wrote:


"Bob" wrote in message
...
I'd like to add a quality grounding rod to my house. I know from prior
research, that ground water exists from maybe 12
to 17 feet below ground, below which is hardpan. It seems that a 17 foot
ground rod would give me the best ground, but
10 feet seems to the the longest I can find. Are there longer ground rods
available? Where? Is my reasoning
"reasonable"?

bob

google is your friend
http://www.erico.com/products/copperbonded.asp


quality grounding rod?

I know of no study that has found that getting a ground rod into the water
table is worth the effort. Sure would be hard for us folks in the SW
deserts.

Placement of the "supplemental ground rod" should be outside the sphere of
the primary grounding system. Amec makes a meter that can measure
ohms/volts to ground with out interruption.

http://www.giscogeo.com/pages/grsae371.html My personal favorite.

I measured my last house and found that the installed ufer ground was less
than 10 ohms. Not much reason to spend the effort in setting another
ground
in that situation. That was done on a dry July morning.

From the picture and the text that device is only measuring current. Its
somehow calculating resistance based on that - I cant imagine it being
anywhere's near accurate. If it were that simple you could use your clampon
ammeter and a table.
Eric