>
> I'm not even sure that a deep rod is particularly useful
for lightning
> protection, since the pulse duration of a lightning surge
is so short that
> it behaves essentially like rf. I added some 20' radials
to the ground rod
> at my service entrance for better protection.
> Any other thoughts or opinions on this issue?
> Don K4KYV
There is a complex soup of things going on with a ground rod
driven into earth. First, the soil is almost never a
homogenous media. Second, the contact area is small and the
rod contacts and passes through that lossy media all the way
up. I believe this makes things look worse for the rod tip
than we might expect from a look using only skin depth as a
criteria.
In my own tests here, a ten foot copper 1" pipe driven full
depth wasn't really significantly better than a five foot
pipe when I measure rod RF resistance. I'd rather install a
dozen five foot rods than one ten footer anyway!
This could be a "local event" caused by how my soil is
layered. I have a few inches of dark dirt, then red clay
and fine rock mixed.
It doesn't look bad based on the rate of attenuation of BC
signals (5mS/m to 10 mS/m) but getting a connection with a
ground rod might be something different.
73 Tom
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