[Towertalk] Connecting grounds to towers

[Bill Ralston]

> From: Bill Ogden <ogden at 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