Topband: Ground rods vs radials

[Tom Rauch]

>
> 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