[TowerTalk] Rohn BPC25G

[Gary Schafer]

> -----Original Message-----
> From: towertalk-bounces at contesting.com [mailto:towertalk-
> bounces at contesting.com] On Behalf Of Mark Robinson
> Sent: Sunday, May 13, 2007 9:17 PM
> To: TowerTalk at contesting.com; Jim Garland
> Subject: Re: [TowerTalk] Rohn BPC25G
> 
> 
> 
> >
> >>
> >>Dont ever put a ground rod in the concrete base. A lightining strike can
> >>easily explode the concrete.
> >>
> >>Carl
> >>KM1H
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> 
> > I've heard that for years, but I read recently (I think on the
> > Polyphaser website, but I could be wrong) that that is an urban myth
> > and that grounding a rebar cage is actually very desirable.  Does
> > anybody know someone who's actually exploded a concrete base?
> >
> > Jim W8ZR
> >
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> 
> Connecting the rebar together and out of the top of the concrete as an
> addition to the ground system is called a ufer ground. This uses the
> conductivity of the damp concrete to couple to the soil. Do a google
> search
> on ufer ground
> 
> I believe that you want to avoid having the rebar sticking out of the
> concrete block into the soil underground as this is a direct path into the
> soil.
> 
> 
> Mark N1UK
--------------------------
You don't want anything sticking out of the concrete either rebar or a
ground rod. Not because it is a lightning path but because it will corrode
(rust) and the corrosion will work its way up into the concrete and that
will crack the concrete.

It is fine to use the rebar inside the concrete as an auxiliary ground for
the tower but it should all be tied together in the concrete so that there
is no arcing from one piece to another in there.

It is just as important to build the concrete so that no water accumulates
around any pier pin or j bolts sticking out of the top too. If they rust
down into the concrete you will have the same problem with the concrete
cracking.

73
Gary  K4FMX