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Re: Ground rods + tungsten

>>From bmcpeak-at-gte-dot-netTue Sep 24 22:23:04 1996
>Date: Tue, 24 Sep 1996 06:38:44 -0500
>From: Brad McPeak <bmcpeak-at-gte-dot-net>
>To: tesla-at-pupman-dot-com
>Subject: Ground rods

>Hello all,
>I have a few questions about grounding. I have access to 8ft. sections of
>Stainless Steel Tubing (free) would this work for ground rods. I know Copper
>(not free) is best. Also I was going to put them under my covered deck to
>keep them out of the way, but the earth is dry under there, would it be
>better to put them somewhere wetter? And last does anyone know of a mail
>order source for Tungsten TIG points or rod? I called a few welding supply
>places in the Dallas area and they didnt know what I was talking about? Thanks.

>Brad McPeak 

Brad,

As long as you are physically able to sink them into the ground, I 
expect the stainless steel tubing should be an excellent choice.  You 
won't have to worry about corrosion.  Sure, S.S. is not as good a 
conductor as copper, but neither is soil.  I heard of a trick of 
hooking up water pressure from a garden hose to allow one to bury 
soft copper water pipe.  This could be done with the stainless tubing 
if necessary.

Sure a wetter place is better.  Wet or dry, I'd sink a number of these 
rods, several feet apart as a minimum.  Use stainless steel hose 
clamps to connect large guage copper wire to them.  Soil dry on the 
surface but damp below would be fine, but avoid pounding a ground rod 
its entire length into dry soil or sand, it will not be effective.  
Spacing is good.  If you have enough large guage interconnect wire or 
strap, 15 foot spacing between 4 or 6 driven rods would be far better than
2 foot spacing.  For my 7 and 10 kW systems I use #0000 flexible 
welding cable for ground wire up to 50 feet with good results.  For my 900 watt 
system #14 up to 10 feet long seems to work OK.

TIG welding is extremely common and popular nowadays.  If the shops 
you called didn't know what TIG welding electrodes were, they're 
definitely not in the welding supply business.  These are about 7 
inches long and are machined to a fairly nominal diameter in sizes 
from about 1/16th inch, in 1/32th increments (I think) up to about 
3/8nd inch diameter.  They are EXPENSIVE.  I pay about $5.00 U.S. 
equivalent for a single 1/8th inch thoriated tungsten rod.  These are 
designed to fit into a handheld pistol type grip that feeds a 
welding gas in through a hose and regulator from a tank to provide 
an oxidation free zone around the weld as you are melting the metal.
TIG electrodes are available for welding aluminum, and for welding 
steel.  You want the ones for welding steel. 
 
Tungsten is extremely hard.  You will instantly ruin the highest 
grade steel hacksaw or power saw blade.  Grinding is the only 
practical way.  They can also be electromachined.  I bought one of 
those dual wheel bench grinders and a special, green, silicon carbide 100 grit 
stone wheel just for cutting and dressing tungsten electrodes.  To 
cut them I roll the rod against the corner of the stone between my 
fingers.  Once in quite a way I just snap the joint.  Careful, 
tunsten is as brittle as it is hard.  Then I face them and take the 
rough edge off.  Keep a can of cold water next to you.  You will need 
it constsntly to cool the rod as you work with grinding it, so as to 
avoid burning your fingers.  Other contact material which I am very 
pleased with is pure tungsten carbide cutting tool squares that are 
made to be clamped into or brazed onto the end of a tool bar for use 
as the cutting tool in a lathe.  A square of this material can be 
brazed onto the end of a steel post or bolt and then machined on the 
grindstone to shape.  I use this material as stationary electrodes on my MTC 
system rotary with 1/8th inch thoriated tungstens about 2.5 inches 
long as the flying electrodes mounted in setscrewed steel holders on the wheel. 
I've seen absolutely no wear yet on a machine that was eating shaped grade
12 bolts as stationaries completely in just 3 minutes of run time.  The 4th of
July show from incandecent vaporized metal particles flying out of the gap
has now stopped with use of the tungsten as well.

Good luck.

rwstephens