The reason why are you driving rods (multiple ones at that) will determine
your best course of action.
Is it for:
Electrical Safety - green wire ground
Lightning protection
RF ground
Practice driving long spikes into the ground (<grin>)
For the first, it's easy, use a UFER ground, which is approved (and
generally recommended) by almost all permitting authorities and the NEC.
Here what the ground hole looks like, etc. isn't as important as making sure
that your installation follows the rules. All the schemes allowed in the
rules make a perfectly adequate safety ground, if properly installed. This
is not to say that there aren't thousands of other schemes for grounding
that won't work just as well, but, the code required methods aren't all that
big a deal. Most local electrical permitting agencies will have a handout
for what they want to see (lots even have the handouts on line, like County
of Ventura, in southern California). You can dig a trench and lay the rod
sideways if you want to.
For lightning, a UFER ground is also probably your best bet. It was
invented for use in areas where there's high soil resistivity, etc, (i.e.
the arid southwest), and makes use of the fact that concrete is a fairly
good conductor (compared to soil). Take a look around the neighborhood at
commercial buildings built in the last 10 years or so, and see what they use
for a lightning ground. The buildings out at NASA White Sands Test Facility
in Las Cruces, NM, use UFER type grounds and lots of bonding cables from top
to bottom
For RF ground, rods aren't all that hot as a ground, anyway. A smallish
radial network will blow the doors off any reasonable ground rod. (Consider
the surface area of half a dozen 10 foot radials, compared to a single 10
foot rod, and the resistance to the "surrounding soil").
Other strategies:
Use lots of short rods, spaced more than the rod length apart, bonded with a
suitable conductor (exothermic welding, etc.)
Use a ground grid (this isn't radials, but a crosshatch)(this is usually
done only in areas where step potential on a fault is important (i.e. in an
electrical substation).
In general, using salt or chemical treatments to improve soil conductivity
is looked upon with disfavor these days. They eventually leach out and then
you're back to a regular old rod in the ground. If you can't get a low
enough ground resistance (for Electrical Safety/Lightning) with a single rod
or UFER, then you go to more rods, bigger grounding grids, etc.
There is also the problem of a "perception of toxic waste". Whether or not
it actually is safe to put some sort of salt in the ground, it gets into all
sorts of paperwork, and, you also face the risk of changes in policy (It
used to be ok to dump DDT manufacturing byproducts into the river, right?
Or, more relevant to the southwest near Las Vegas, perchlorate rocket
fuel...)
----- Original Message -----
From: <WarrenWolff@aol.com>
To: <towertalk@contesting.com>
Sent: Friday, December 26, 2003 9:57 AM
Subject: [TowerTalk] Pre-dug ground rod holes
> What does that mean? I must be too too slow. Are you saying that all
> communities have signed on to Copper Sulfate intrusion?
>
> I fully planned to have a hefty auger dig the holes for my ground rods.
My
> soil is quite rocky at Lake Havasu City.
>
> The words I have received have always overstated the threat of
> copper sulfate (fish kill, for example). None of the fish died in
> my old home town lake and folks ate the fish from there all the
> time. Just killed the weeds. And the soil in central Texas would
> support osmosis easily.
>
> So, let's get back on focus; what should be my plan B for holes that are
> auger
> drilled? Hand digging ground rod holes there would take an eternity, it
> possible
> at all. Surely, driving the rods seem nigh upon impossible. Have not yet
> talked to
> residents. Will be there in a few days.
>
> > assume this is a joke, unless you enjoy Phase2 environmental cleanups.
> > Do your neighbors have wells?
>
> Blake N4GI
> _______________________________________________
>
> See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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