Mike Kaliski wrote:

wrote in message
...
Mike Kaliski wrote:

"Rick (W-A-one-R-K-T)" wrote in message
news
OK, per the thread on "Question on grounding rods", I'm supposed to
use
8-foot grounding rods rather than twice as many 4-foot rods. I can
see
that.

But, we're built on a ledge, one big wide rock that stretches from the
seacoast to the Vermont state line (that's why they call New Hampshire
the
"Granite State"). I can get three feet depth at best before running
into
solid rock. An electrician friend of mine says I can drive the ground
rod
in at a 45-degree angle, but that would still run an 8-foot ground rod
to
a depth of more than 5.5 feet below the surface.

Can't be done.

So, what do I do next?

Rick

Check out some new builds in the area and see what earthing arrangements
are
being put in there. The new properties will obviously have to conform
with
the latest regulations. If the builders have to use a specially long
drill
rig, you might be able to bribe them to come and drill you a few new
holes.
Failing that, its welding a long tube onto whatever you have that will
drill
through granite and then spending a couple of days drilling downwards.
Radio
hams are supposed to be renowned for their ingenuity and determination
when
faced with tricky situations. Build an echosounder or ground resistivity
meter and scour the plot looking for a crack you can drive rods down
through? The possibilities for experimentation are endless.


What purpose would be served by putting a grounding rod in solid rock?

All codes/regs I've seen have alternatives for special situations like
this, such as buried plates or several horizontal, interconnected,
buried rods.

--
Jim Pennino

Remove .spam.sux to reply.

Jim

Yes, you're absolutely right. I was just thinking about how to punch down
through 8 feet of rock rather than the end purpose. Ground radials, plates
or earth mats buried as well as possible in the soil make a lot more sense.

Mike G0ULI

There are other conciderations as well such as is this an electrical
ground to meet some code, a lightning protection ground to keep your
insurance in force, or an RF ground to make your antenna work?

--
Jim Pennino

Remove .spam.sux to reply.