I suspect the important aspect is the surface area interfacing with soil, not
the volume of dirt under or surrounding the grounding system. That 6x6x6 cube
has far more surface area in contact with the soil than does even a dozen
ground rods and a radial field. Even if you compare just the surface area of
the bonded rebar in the concrete, it is probably more surface area for
transfer. I’ve never heard of a tower base exploding from the energy of a
strike. Has anyone?
Thomas W Noel
KF7RSF
> On Aug 8, 2015, at 10:32 AM, JVarney <jvarn359@gmail.com> wrote:
>
> Again, I'm not aware of the committee's reasoning. Just my personal
> opinion: I don't see how the math checks out for Ufer grounds for towers. A
> multiple radial and ground rod system might offer on the order of 10,000
> cubic feet of earth for lightning to dissipate to. With an Ufer on a tower
> with a 6x6x6 footing, that's only 216 cubic feet of volume available to
> dissipate one trillion joules of energy. If I'm building a tower I'd rather
> direct the lightning energy away from the tower versus concentrating it in
> the footing, IMHO.
>
> 73 Jim K6OK
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