At 03:21 AM 7/9/2006, Dr M J DiGirolamo wrote:
>Dear TT Colleagues,
>
> There has been so much discussion here about dealing with lightning
>protection and grounding systems that I can't remember whether I read
>about the
>following topic or not.
>
> I'm planning a ground radial system for each tower leg (yes, a peripheral
>ground system and single point ground, etc too) and have decided to use a
>heavy
>braided tinned copper cable as the radial for each of these legs. I have just
>about ruled out copper ribbon for various reasons. Ground rods will be 6'
>or 8'
>deep set on 12' or 16' centers.
>
> Question is: Cadwelding is VERY EXPENSIVE when used to attach the
> radials to
>the ground rods! Can anyone comment on whether there will be sufficient
>bonding and heat protection if a heavy silver solder bond is made in place of
>the cadweld. I realize that cadwelding forms a molecular bond but it's
>just so
>darn expensive.
A couple observations...
The ground resistance from a buried wire 16 ft long is probably comparable
to a pair of 8 foot rods connected above ground by a 16 ft wire. Why not
just trench or slit and bury the wire? No connections to worry about, no
rods to buy, etc.
Cadweld oneshots from Tessco are only $6-7 each. I imagine that the cost
of the ground rod is comparable..[Tessco shows a Harger 8'x5/8 rod is $17
(list)]. Ultimately, you're looking at a cost/benefit tradeoff (better
ground = lower risk of damage from transients).. Assuming you've got 3 legs
on your tower, and a couple ground rods on each, you're looking at $60 or
so for the CadWelds.. that's not a huge number compared to the several
kilobucks you've got into the tower/antenna/radio....
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