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Re: [TowerTalk] Screw Anchor Question

To: <towertalk@contesting.com>
Subject: Re: [TowerTalk] Screw Anchor Question
From: "Don Moman" <ve6jy@3web.com>
Reply-to: Don Moman <ve6jy@rac.ca>
Date: Mon, 16 Jan 2006 07:43:01 -0000
List-post: <mailto:towertalk@contesting.com>
I would make sure any guy wires are broken up by insulators so that no DC
current (caused by the difference in potential of the different ground
points)  would flow into the ground thru the anchor rod.  A rough rule of
thumb is that 20 lbs of material is removed by 1 ampere flowing for 1 year.
Do the math and it doesn't take much to remove enough material for a thin
anchor rod to fail.

However I like screw anchors and use them for many of the towers here. But
it is important to know what conditions may cause them to be weakened.  I am
not concerned about them floating out of the solid Alberta subsoil I have
around here.

I have been told, or read somewhere, that the test to destruction failure
point of screw anchors is that the weld holding the helix to shaft will fail
before they pull out or break the shaft.

73 Don
VE6JY


----- Original Message -----
From: "K8RI on Tower talk" <k8ri-tower@charter.net>
To: "Phil Camera" <kb9cry@comcast.net>; <towertalk@contesting.com>
Sent: Monday, January 16, 2006 07:24
Subject: Re: [TowerTalk] Screw Anchor Question


>
> ----- Original Message -----
> From: "Phil Camera" <kb9cry@comcast.net>
> To: <towertalk@contesting.com>
> Sent: Sunday, January 15, 2006 7:45 PM
> Subject: Re: [TowerTalk] Screw Anchor Question
>
>
> > Don't take this personally, but IMHO screw anchors are only to be used
> > for a temporary installation.
> > A 70 ft. tower is a sizable structure and needs adequate anchors,
> > meaning, anchors that have concrete holding them in place.
> > Yes, you should be concerned about the anchor in question, as well as
> > the others.
> > If you get Zero rain, and I mean none, then your anchors may last.  But,
>
> We get quite a bit of rain around here, but screw anchors seem to last
> forever.  20, 30 years and you still see no corosion.  OTOH you don't want
> to plant them near a marsh.   I think a lot depends on the PH of the soil.
> You see a lot of lime sperad on farm land that was once swamp.
>
> > if your location gets any kind of rain, then that soil can become very
> > soupy and won't hold worth squat.
>
> Again, it depends on how much rain and what kind of soil, but for me, I'd
> not use screw anchors except in an emergency or it they were the only
viable
> method available. (or on a small tower)
>
> Roger Halstead (K8RI and ARRL 40 year Life Member)
> N833R - World's oldest Debonair CD-2
> www.rogerhalstead.com
>
> > I'd seriously rethink your installation.  Gd Luck and be safe, Phil
> > KB9CRY
> >
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> >
> >
> >
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