In regard to the stainless steel shims - I recently did the same, after
spending a lot of time finding the darned stainless steel. I finally
located some at a large sheet metal shop. They had some .002 and .005 stock
on hand, rolled up in tubes. According to them, they'd had it for several
years and no one had ever asked for it before. I also ran across some
small stainless strips in a local "old fashioned" hardware store that
carried very small diameter tubing and strips for hobby use.
----- Original Message -----
From: "Bill Ralston" <n7vm@lgcy.com>
To: <towertalk@contesting.com>
Cc: <ogden@us.ibm.com>
Sent: Friday, November 14, 2003 11:24 AM
Subject: Re: [Towertalk] Connecting grounds to towers
> > From: Bill Ogden <ogden@us.ibm.com>
> >
> > What is a reasonable way to connect ground wires to a tower (a TX-455,
in
> > this case, with the tilt-over feature)? I plan on three ground rods and
> > about 50 radials. I'll probably use insulated #14 wire (from Home
Depot)
> > for the radials and #8 bare for the ground rods.
>
> I'd think about using #4 solid Cu or Cu strap - bigger the better. #4 is
> avail at Home Depot.
>
> I would run three wires from the base or tower leg to the ground rods, and
> then run a ring around the base tying all three ground rods together.
Most
> folks here seem to thing the cadweld one shots are the way to go, but I've
> haven't tried that and have just been using standard ground clamps and
split
> bots to make connections.
>
> One way to attach the ground lead to the tower is to buy a Polyphaser
clamp.
>
> Another way is to put wrap stainless steel around the tower leg and then
lay
> the ground wire against the stainless and hold in down with stainless
steel
> hose clamps. I did this, which gave me about 6" of contact between the #4
> ground wire and the tower leg, with the stainless to prevent the galvanic
> corrosion. This is similar to the polyphaser clamp. The building
inspector
> vetoed that, insisting upon an "approved ground clamp"
>
> I replaced this with standard ground clamps designed to go on a pipe (also
> available at home depot). As these are made of bronze, there is still a
> concern about galvanic action, so I placed shims of stainless between the
> tower leg and the clamp. Since the area of contact between the clamp and
> the grounding wire is quite small, I used three of these in parallel for
> ground lead. The problem is that most building codes / inspectors are
> really only concerned with DC grounding, and do not understand RF or
> lightning.
>
> Another option might be to find a large enough terminal (again, look in
the
> electrical dept at Home Depot) that will go onto the bolt that is designed
> to receive a large wire. Again, be careful about galvanic mismatches.
You
> might even machine something out of stainless if you are really ambitious.
>
> >I am surprised about how little mention there is of practical mechanical
> >problems in the handbooks.
>
> No kidding - I struggled with this for quite some time
>
> de Bill N7VM
>
>
> _______________________________________________
>
> See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
>
> _______________________________________________
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> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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