Jerry:
This is an old wive's tale. The use of the foundation
reinforcing as part of the ground is called a "Ufer
ground" after the guy who first devised the concept.
It is a very common way to ground machinery, electrical
systems, and buildings. I have used this type of
grounding in my designs for over 30 years and have not
seen what you describe despite the best attempts of
Mother Nature.
73
Hank Lonberg, S.E.,P.E. / KR7X
Lonberg Design Group
> I can recall a commercial tower design firm (1,000 and 2,000 foot broadcast
> towers) telling me that you never run a ground cable through a concrete base
> or guy anchor. That the rebar cage is intended for strength not grounding.
> That if you run a lightning strike through the foundation or guy anchor, the
> concrete will crack if the lightning tries to exit the concrete looking for
> real ground ground or from the heat of the lightning. Is this theory
> incorrect?
>
> Jerry, K6JRY
> ____________________________________________
>
> -----Original Message-----
> From: towertalk-admin@contesting.com
> [mailto:towertalk-admin@contesting.com]On Behalf Of Red
> Sent: Thursday, September 19, 2002 3:56 PM
> To: FireBrick
> Cc: Andrew Pfeiffer; towertalk@contesting.com
> Subject: Re: [Towertalk] Rebar Cage
>
>
> In addition, welding all joints helps the rebar distribute lightning
> discharges through the concrete, making your base a "Ufer" ground, named
> after the investigator who established its value. The welded cage
> assembly can then be set into the hole and braced with 2X4, with wires
> or ropes to pull them out as the concrete is poured.
>
> 73 de Red
>
> FireBrick wrote:
>
> >As a retired mason contractor, I can see where you are going.
> >You want the verticals stable so you can easily wire the horizontals on
> >while in the hold.
> >Ideally, rebar should not extend through the concrete, rebar should not be
> >within 4" of the concrete.
> >This is to minimize moisture reaching the rebar and eventually rusting.
> >
> >If your worried about the rebar cage maintaining it's shape during
> >construction.
> >Stick the verticals in the ground at the surface. It's easier to work on
> >then in the hole.
> >Then have someone help you lift it and place in the hole.
> >
> >I also strongly suggest a little gravel in the bottom of the hole which
> >makes positioning the cage easier. You can wiggle it a bit to get it plumb.
> >
> >The trick with all rebar cages is to maintain their shape and position
> while
> >dumping and vibrating the concrete.
> >If you gut a couple boards and drill holes to match the vertical rears, you
> >can nail/clamp to braces on the surface.
> >
> >
> >----- Original Message -----
> >From: "Andrew Pfeiffer" <va3pl@cuic.ca>
> >To: <towertalk@contesting.com>
> >Sent: Thursday, September 19, 2002 11:36 AM
> >Subject: [Towertalk] Rebar Cage
> >
> >
> >>I become happy owner of TX455 crank up tower. I began planning the rebar
> >>cage.
> >>My questions is:
> >>Can vertical rebar members be driven let say 2 feet deep to the ground at
> >>the bottom of the hole or this is NO NO...
> >>
> >>Andy - VA3PL
> >>
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> >
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> >>
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> >
> >
> >_______________________________________________
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> http://www.mscomputer.com
> >Call 888-333-9041 to place your order, mention you saw this ad and take an
> additional 5 percent off
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>
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> _______________________________________________
> Self Supporting Towers, Wireless Weather Stations, see web site:
> http://www.mscomputer.com
> Call 888-333-9041 to place your order, mention you saw this ad and take an
> additional 5 percent off
> any weather station price.
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>
> _______________________________________________
> Self Supporting Towers, Wireless Weather Stations, see web site:
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> Call 888-333-9041 to place your order, mention you saw this ad and take an
> additional 5 percent off
> any weather station price.
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