Thanks, Jim.
One "run" of rod/wire is to go tie into the service ground. That's worthwhile,
yes?
Mike
On May 26, 2014, at 9:14 AM, Jim Lux <jimlux@earthlink.net> wrote:
> On 5/26/14, 5:49 AM, Mike Reublin NF4L wrote:
>> The base for my crank-up tilt-over 70' tower is poured in a 48"
>> diameter 10' deep steel culvert. My ground wires are attached to the
>> rebar and were also supposed to have been attached to the culvert,
>> but were not (long sad story). It would be very very difficult to
>> attach them to the culvert now.
>>
>> I will drive 2 or 3 rods out from each leg. Should the first one be
>> next to the base, or a couple of rod lengths away?
>>
>
>
> The concrete inside the culvert already gives you a better path to "earth"
> than a few rods. A rod driven next to the base would make almost no
> difference.
>
> You'd have to get pretty far away before it would make a difference (the
> usual "spacing of the rods" rule of thumb is for rods that are very thin).
> By the time you get 20-30 feet away, the series inductance of the wire going
> to the rod means that it's not going have much effect.
>
> If you want to reduce "step potential" (the voltage gradient on the surface),
> you'd be better off using the money to bury radials, which has the useful
> side effect of increasing the apparent soil conductivity for HF frequencies
> (and reducing "ground losses" if you operate your tower as a vertical). If
> you'll never use your tower as a vertical, then radials aren't all that
> useful either.
>
> You've got a great grounding electrode now.
>
>> My raising scheme is a length of 4" diameter pipe embedded 3.5' in
>> the concrete a yard behind the tower. Two diagonal braces will run
>> from the pipe to the front leg mounts.
>>
>> Will 2" water pipe work? Sched 40 or 80? Angle iron?
>>
>> 73, Mike NF4L _______________________________________________
>>
>>
>>
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>
> r
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