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Re: Weather/coil performance
Original poster: "David Rieben" <drieben@xxxxxxxxxxxxxxx>
Hi Dr, all,
Actually, all of the copper-clad ground rods that I have
bought in home Depot or Lowes are 8 feet long. Their
diameter does vary from 1/2" to 5/8", with the 5/8" dia
ones obviously being a bit more costly. The addition of
salt while driving the rod into the ground is a different
idea that I would have never thought of. The only thing that
I wonder about in this scenario is the salt corroding the cop-
per cladding and ultimately reducing the concuctivity. I think
the surface of copper is going to eventually oxidize in the
presence of persistant moisture anyway, though, so the salt
thing is probably a good idea. I drove (3) 8 ft rods only 4 ft
apart and interconnected them with heavy braided welding
cable (1-0 AWG, I think) for the grounding system of my
Green Monster coil.
As far as the freezing moisture is concerned, I think an
8 ft. ground rod should reach well below the frost line
level for most of us, unless you're coiling on the North
pole or in Antarctica ;^) To get an idea of the frost line
of your area, check your local plumber's depth level code
for burying water lines and that will give you a good idea
of depth level that the ground would never be expected to
freeze to in your locale. I'm in the Memphis, TN area and
in my area, the water lines must be buried 18". I'm suspect
that depth requirement would be considerably greater in say
Minneapolis or Calgary, but still not near the near 8 ft depth
that can be reached with an 8 ft. long ground rod. I would
suspect the loamy, alluvial soil of the eastern US and Canada
would conduct better than the more arid rocky and sandy soil
of the western US and Canada, too.
----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
Sent: Thursday, January 18, 2007 10:57 PM
Subject: Re: Weather/coil performance
> Original poster: "resonance" <resonance@xxxxxxxxxxxx>
> Most copper ground rods are 6 feet long which means the lower 30
> inches is usually in soil that has some moisture and, especially in a
> mild winter like we have had the past 4-5 years, the lowest 30 inches
> of the copper rod lie in unfrozen soil.
> When driving a new ground rod try this: drive the rod in approx 30
> inches, then wiggle it and remove it leaving the hole. Pour approx
> 4-5 tablespoons of salt into the hole, add approx 1/4 cup of water,
> and then redrive the ground rod all the way in. The sodium ions will
> slowly migrate outward and help to produce a larger ground area
> "field" that helps the electic RF currents link up with the moist,
> conductive earth. We usually spec this for science museums and ask
> them to drive two ground rods approx 15-20 feet apart and then
> interconnect them with a 2 AWG fine stranded copper welding cable. A
> single 2 AWG welding cable goes directly inside the museum wall using
> the shortest possible path to the Tesla transformer. This provides
> an excellent ground for the RF currents and helps minimize
> interference while maximizing the coils performance. We spec the
> connection is covered liberally with grease to help prevent corrosion
> and oxidation of the copper rod connection.
> A great ground can usually improve a medium size coils performance
> with 4-6 inch more spark than a poor ground or an electrical ground
> through the conduit.
> Dr. Resonance
> >Beware the Frozen Ground.
> >If an outdoor 'ground' be used, once the dirt at the
> >ground level freezes the ground gets worse.
> >Documented in notes here, past. Also well documented in
> >professional (power line, RF) ground studies.
> >Most significant on 'hi power coils', typically.
> >Sometimes goes away after 'some' operation, as the
> >current melts the ice.
> >If dirt 'ground' be deep enough: not an issue.
> > Once the water is no longer liquid, the ions that
> >allow current flow are trapped, more or less immobile.
> >If natural warming, or warming from current from coil
> >melts water around 'ground electrode', thing simprove.