A Ufer ground doesn't necessarily call for a welded rebar cage. The NEC code
doesn't require it, and there have been several studies showing that
properly wired rebar provides sufficient conductivity. However, it's
possible that welding is required by the buiding codes in some
jurisdictions, so you should check with your local code officer.
FWIW, my local building inspector required a Ufer ground. I wired the rebar
cage and used high-quality aluminum clamps with conductive grease to attach
three ~50' pieces of 1/0 stranded ground wire to the cage. I ran one end of
each wire up through the clamp so that it extended above the tower base by
about two feet. After the pour, these pigtails were attached to the tower
legs, bonding the tower to the rebar cage (I have a pier-pin base.) The
other ends of the 1/0 wires extended out the side of the base hole and were
coiled up during the pour. After the pour, I had a guy with a Ditch Witch
dig three 48' trenches extending from the base and laid the 1/0 wire in the
trenches. Then I pounded in 8' ground rods every 16' in each trench and
Cadwelded the 1/0 wire to each rod. Lots of work!
You can see pictures of most of this on my website at www.wc1m.com. Click on
"Big Tower Project" on the left, then click on "Pier and Anchors" or "Ground
System".
73, Dick
> -----Original Message-----
> From: Dr M J DiGirolamo [mailto:DrD@2020.com]
> Sent: Wednesday, December 10, 2008 11:08 AM
> To: towertalk@contesting.com
> Cc: k4kyv@hotmail.com
> Subject: Re: [TowerTalk] Rebar Cage Question
>
> Don,
>
>
>
> I built my cage from "weld quality rebar" and it was welded by a
> friend.
> My friend is a certified master welder at a nuclear power plant here
> in
> Virginia. It took him the better part of a day to do all the work for
> me.
> Believe me, he knew what he was doing and it still took him that long.
> Fortunately he did it as a friend, free of charge! It weighed over
> 400#
> when done. This cage was built to spec for a USTower 72' stand alone
> series
> of towers. I wanted to employ a Ufer ground and that calls for a
> welded
> cage. As mentioned in another post, it requires a special type of
> rebar
> (quality of metal mix is monitored) and it's only a little more
> expensive
> should you decide to go that way.
>
>
>
> Drop me a note if you would like some photos and keep us posted
> regarding your progress.
>
>
>
> 73,
>
>
>
> Mike DiGirolamo, W4XN
>
> Charlottesville, VA
>
>
>
> 73,
>
>
>
> Mike, W4XN
>
> ----------------------------------
>
>
>
> Date: Wed, 10 Dec 2008 08:21:26 +0000
>
> From: Donald Chester <k4kyv@hotmail.com>
>
> Subject: [TowerTalk] Rebar Cage Question
>
> To: <towertalk@contesting.com>
>
> Message-ID: <BLU113-W605AC74CBAF2140D0D56ECF4FB0@phx.gbl>
>
> Content-Type: text/plain; charset="iso-8859-1"
>
>
>
>
>
> I have heard it said many times that one should not weld the rebar
> cage
> together, but tie it together using tie wires. But I have never heard
> any
> explanation of why.
>
>
>
> What problems would be caused by welding? I can't see how such a
> minor
> detail would make any significant difference, but a welded cage is
> certainly
> easier to handle before the concrete is poured in, and less likely to
> fall
> apart just as the concrete is being dumped.
>
>
>
> Don k4kyv
>
>
>
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