Have been reading the several comments about grounding for towers. For
those souls who live in Central Florida (the lightning capitol of the
world?), and other similar ground areas, I thought I'd share a bit of my
experience on the subject. I hope it will be of some help to others who
might be lulled into thinking 1 ground rod is sufficient.
After moving to my present QTH a few years ago, I quickly put up my 68
foot tower and drove a 10 groud rod at the base. A while later, I became
concerned about the ground conductivity of the sandy soil here and
borrowed a ground tester from a friend at the power company. What I
measured on my 10 foot ground rod, was 750 ohms! Being quite surprised,
I decided I had to go deeper, I secured some threaded rods and couplers,
and an electric driver. I had to drive 55 feet to get a 5 ohm ground.
You could see quite easily where the ground impedance started to fall
(getting into moist earth), at about 45 feet. I eventually drove 4-50
foot plus rods, with 1 at the tower and the others about 40 feet, and
axial, from the base. I then bonded them together with 4-0 copper
stranded wire, buried in the ground.
Maybe some will say that was a bit overkill. I'm not sure it is for this
area. Let me suggest a conversation with some of the local power company
outside installers and techs, can be quite helpful for what is typical
for your area. But a single rod should be viewed as a very questionable,
and certainly as minimal, for lightning protection and/or a good RF
ground.
I hope this is helpful to anyone who might be concerned with such things.
73,
Ray, W4BYG
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