[TowerTalk] Ground Rods into Concrete Stubs

[Stan or Patricia Griffiths]

I have to take exception to the comment below about not allowing any metel inside
the concrete base of a tower to extend outside the concrete.  In the case of a
Rohn-type tubular leg tower where the base is a short section set in concrete, you
had better let the legs extend below the concrete in the base in order to allow the
water that accummulates in the legs to drain.  Otherwise, it will freeze there and
split the leg tubing just like water always does when it freezes in a water pipe.

Stan
w7ni@teleport.com

R. Otto wrote:

> Hello Mike,
>
> I am no expert on the question you raised, but here's two things to
> think about:
>
> 1)  I've always been told it's not a good idea to allow any metal used
> as structure inside concrete to go outside the concrete -- that if you
> do the metal will rust inside the concrete.  That's why (I'm told
> anyway) that you never let rebar extend outside the concrete.  Doing
> what you suggest would allow a rust path to your clevis rods.
>
> 2)  I've also been told that it's NOT a good idea to run any kind of
> grounding rod or wire directly through the concrete.  If you take a
> lightning hit -- the intensity of the charge will be so great that it
> will "super-heat" the concrete and cause it to explode.  What happens
> is the moisture in the concrete (there is moisture in concrete even
> long after it's cured) expands much more rapidly than the cement,
> causing the cement to explode.
>
> Again..........this may be all "old wives tales" but I've followed the
> concepts in my installations.........
>
> 73's from.......
>
> R. Otto
> N8NGA@one.net
> Cincinnati, Ohio
>
> *********************************************
> DXCC 10M         ** DX is !! **       WAS 10M
> *********************************************
> Thursday, August 17, 2000, 11:10:07 PM, you wrote:
>
> MF> I'm in the process of getting a tower put in, a 48' Rohn HDBX.
>
> MF> Is there any reason that I can't take and attach 3 ground rods to the BOTTOM
> MF> of the base stubs (that are buried in the concrete)?  That would put them
> MF> another 4-5 feet down.
>
> MF> I am planning on also putting in some more ground rods (8 footers I imagine)
> MF> in the immediate vicinity also.
>
> MF> Mike
>
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