Jim Lux wrote:
Sal M. Onella wrote:
Dave Lemper wrote in message
...
The soil in central Texas is called Caliche with a lot of clay,
CaCO3 & shale. Attempting to drive in a ground rod
yielded only a mushroom on top & blisters on me.
Local tool rental place has concrete bits, but maximum
length of 18 inches. Possibly longer bits are available in
a larger city.

Renting a back hoe is out.
Any suggestions appreciated.
Dave WB3DWE



Here's a snippet from the state of Washington's website that quotes
the NEC:

NEC 250-52 (c)(3) (1999 edition) requires that ground rods "be driven
to a
depth of not less than 8 feet
(2.44m) except that, where rock bottom is encountered, the electrode
shall
be driven at an oblique angle
not to exceed 45 degrees from the vertical or shall be buried in a trench
that is at least 2½ ft. (762mm)
deep."

The requirement is that the rod be driven to a depth of 8 feet. If the
rod
cannot be driven then there is a
choice of either driving it at a 45-degree angle or laying it in a trench
that is not less than 2½ feet deep.

http://www.lni.wa.gov/tradeslicensin...ts/elc0210.pdf.


I browsed some newer discussions and found nothing newer to be at
variance
with the quoted material. The current NEC is $75 if snippets won't do
ya'.

http://www.nfpa.org/itemDetail.asp?c...RL=Pub licati

ons/

You need 25 ohms maximum rersistance (three-point method) to say you
have a
good ground.



or, do what most jurisdictions now require, and build yourself a
concrete encased grounding electrode (Ufer ground)... no minimum depth,
per se.


The minimum depth is provided by the building code. Since the footer
must be below the frost line the resultant Ufer Ground is also below the
frost line. If it's not it will be ineffective.
--
Tom Horne

"This alternating current stuff is just a fad. It is much too dangerous
for general use." Thomas Alva Edison