On 11/16/12 6:46 AM, K1TTT wrote:
I plugged that into my lightning modeling software... if I put 7 radial
wires(NO rods) 1" in diameter (a bit smaller surface area than 2" strap),
bury it 1' in solid rock (ignoring any advantage of topsoil above the rock)
and run them out 100' (to equal your 700') I get a ground resistance of
about 8 ohms... as good as 20 rods 8' long by 1" diameter in good loam...
still sounds like overkill to me. If I allow for 1' of topsoil on the rock
with the wires on the rock it goes down to under 6 ohms. To put that in
perspective, the 'normal' 2 rods in loam calculates out to over 70 ohms, in
common clay that reduces to 35 ohms.
This brings up an interesting question... Off hand, I would expect that
laying a bunch of radials (not too long, but lots of them) of not very
big wire (AWG14 or AWG12) might be a better lightning ground for the
dollar than any of the other strategies (except concrete and wire..
great ground, and concrete is cheaper than copper)
Time consuming to install (compared to driving a single rod)
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