On 5/5/13 1:41 PM, Patrick Greenlee wrote:
Gene, I didn't think the 6 inch burial related to squeezing a little
more depth out of the rod but was supposed to confer some advantage.
What advantage was not mentioned, just info from the tower mfg showing
the 6 inch burial as part of the grounding system along with clamps or
bolts to connect the other end of the ground wire to the tower leg
(depending on formed or tube leg.) Hence my query. Why would they want
you to bury the connection?
Protection from physical damage.
And to meet the "8 feet must be buried" requirement with an 8 foot long
rod. Don't underestimate the incentive for "cheap".
I share your concern for burying a COTS ground clamp. It just doesn't
seem like a good idea. Thus the query.
I wonder if you wrapped a couple turns of your ground wire around the
ground rod and soldered it on if that wouldn't do as well as the Cadweld
method, not as much fun but but I think maybe as effective.
Soft solder gets brittle and might crack with thermal cycling. I don't
think it would get hot enough to melt out during a strike.
Hard solder (silver solder/brazing) would probably work fine, but is
very "workmanship" dependent. The exothermic welds are sort of "either
it works or it doesn't" and it's obvious if it didn't fire properly.
Of course
not everyone has a torch and skill to solder big heavy heat sinky sorts
of things so Cadweld brings welding to the masses. It is essentially a
thermite reaction with an oxide of copper replacing the rust (iron
oxide) typically used in thermite welding. I haven't tried
oxy-acetylene welding with copper "filler rod" but don't see why it
would be inferior to Cadweld for folks with a torch and know how.
it wouldn't. And if you have a decent relationship with the inspector,
they'd probably approve it, with appropriate inspection of the weld.
What they are looking for is something that is "all one piece of metal"
when you are done, so you don't ahve to worry about cracking or metal
migration over the span of decades.
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