He said his tower was painted. I bought a bunch of unpainted Rohn 65, and
some of the sections had light rust. Since I planned to keep them up a
long time , I painted them. Now, Rohn 65 is flange type tower so it has four
bolts going through it at each leg for a total of twelve BIG bolts. In
addition, each tower lag's flange has an area of over four square inches in
contact with the rotating plate.
The bottom section sat on a galvanized plate for a rotating tower, which
was solidly grounded.
I too, thought the tower was grounded...until the lightning hit. Without
going into too much detail, lots of damage caused by the lightning jumping
from the tower to other earth connections. It turns out there was infinite
resistance on both of my towers at the bottom of the leg and the top of
the tower. That was with 4000 pounds of tower, 1000 pounds of antenna and
Polyrod guys being torqued at 1100 pounds.
One can not assume low resistance at tower joints if they have been
painted.
Bill K4XS/KH7XS
In a message dated 12/28/2012 9:31:12 A.M. Coordinated Universal Tim,
jim@audiosystemsgroup.com writes:
1) You may think that the connections are crummy, but a smart EE friend
who works with towers a lot has observed that with all the weight that's
on it, and the considerable cross sectional area in contact at the tower
junctions, most towers are likely to have connections good enough to
load. I'd say it's worth a try.
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