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Tower Grounding Wire Size

To: <towertalk@contesting.com>
Subject: Tower Grounding Wire Size
From: w5fl@flash.net (Wendell - W5FL)
Date: Fri, 3 Jan 1997 22:57:24 -0600
I bought and read the polyphaser book.  I am installing a 64 foot Rohn =
45 Foldover tower. =20

Tomorrow I will weld the rebar cage for the Rohn 45 Tower section base =
and weld 6 12 inch pieces to the 4 inch dia pipe guy wire anchors.  I =
plan to weld or braze (whichever works) all the ground wires and radials =
to the rebar and guy wire anchors.

Question 1:  How do you weld #6 copper wire to ugly old rebar?

I am planning to use #6 copper ground wire for all radials for lightning =
protection.  Two 32 foot radials to each of the 4 guy anchor posts and =
two 65 foot radials to the tower rebar cage (ufer ground) and tie to one =
tower leg.  How should I tie the tower leg, the ground rod, and the =
rebar cage together?  Where should the #6 that runs 100 foot to the ham =
shack entrance panel tie to the tower?  All the radials will run away =
from the house.  Polyphaser seemed to indicate that you also needed to =
coil up some of the ground wire in the hole and pour concrete over it =
too.

Question 2:  Is #6 awg solid copper ($0.20/ft) wire ok for the radial =
grounding system. =20

It meets NEC codes and the Inductance decrease for #4 awg ($0.30/ft) is =
negligible.  Polyphaser says #24 awg will fuse with a lightning strike, =
but no where could I ever find a minimum wire size that will not fuse.  =
Since this is a guyed tower, I at least get the benefit of a strike =
being split 10 ways (Tower, 4 guy wires, 3 feedlines, and two control =
cables).  How conforting that oly 50% of the lightning energy will come =
in your house if you can't strip it off of the coaxes and control =
cables!!!  Maybe it is not really that bad since a lot of the strike =
energy is dissapated before the feedlines make their 100 foot run to the =
house.

Ground Rods:  I have one sunk 8 feet in solid rock under the tower, and =
each of the guy pipes are sunk 5 1/2 feet in the ground.  Beyond that I =
see no further need for ground rods since they cannot be driven more =
than 2 to 3 feet under the surface horizontally (solid rock is 2 - 3 =
foot down)and they cost $10 each (same as 50 feet of #6 awg copper =
ground wire).


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