Ed, VE4EAR, wrote:
Just getting set to pour the foundation for my new tower - finally. I am
not sure in which manner to proceed with the final grounding step.
I have tied my rebar all together securely, ran a #2 cable all around
the four sides of the cage just to make sure there is continuity across
My first and preferred option was going to be to install a #2 solid
tinned Cu cable from each tower leg through the concrete to the closest
rebar side and continue out of the concrete below ground level to the
nearest ground rod. There will be three ground rods spaced about 6 feet
from the tower all connected together with 1.5" Cu strap ring.
The second option recommended on a couple web sites is to connect the
rebar in the concrete out the concrete below ground to the nearest
ground rod and run a second cable above ground from the tower leg just
above the concrete to the ground rod.
Is there a preference to either option? What have others done?
The idea is to provide a low impedance path AROUND the concrete
for lightning to get to ground, not THROUGH it. Copper strap from
leg to the ground rod, run over the top of the foundation is the
Having a copper strap connecting each of those straps together, on
top of the
foundation would be a good idea, as well, although the relative merit
of it may
be debated, based on the type of tower in use.
Personally, I would not attach the rebar to the tower at all. To do
so only makes
that a more viable path for lightning. In addition, the corrosion
which will take place
with the copper attachments will assure that in 10 years, those
can't be trusted.
Remember, a 90 degree bend in a ground wire is an inductor, and you
want a low impedance
path for strike current. I would run that 1.5" strap from each
tower leg, with an 18" radius bend,
over the foundation, and out to each ground rod.
Jim Jarvis, President
The Morse Group, LLC
Achieving Results in a Changing World
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