Gene, I didn't think the 6 inch burial related to squeezing a little more
depth out of the rod but was supposed to confer some advantage. What
advantage was not mentioned, just info from the tower mfg showing the 6 inch
burial as part of the grounding system along with clamps or bolts to connect
the other end of the ground wire to the tower leg (depending on formed or
tube leg.) Hence my query. Why would they want you to bury the connection?
I share your concern for burying a COTS ground clamp. It just doesn't seem
like a good idea. Thus the query.
I wonder if you wrapped a couple turns of your ground wire around the ground
rod and soldered it on if that wouldn't do as well as the Cadweld method,
not as much fun but but I think maybe as effective. Of course not everyone
has a torch and skill to solder big heavy heat sinky sorts of things so
Cadweld brings welding to the masses. It is essentially a thermite reaction
with an oxide of copper replacing the rust (iron oxide) typically used in
thermite welding. I haven't tried oxy-acetylene welding with copper "filler
rod" but don't see why it would be inferior to Cadweld for folks with a
torch and know how.
I have been putting a few ground rods in where a sledge hammer wasn't making
much progress by using a Harbor Freight Demolition hammer. I have also
welded stainless steel tabs to spots on the side of the rod after grinding
off some copper. In marine electronic applications stainless steel "tabs"
and ring terminals to connect the copper wire to the tabs, when generously
covered with silicon rubber (RTV) lasted well in the damp salty shipboard
environment. I should expect as good or better results in moist residential
venues.
If it turns out there is a real advantage (whatever it might be) to burying
the top of the rod 6 inches I could weld a small SS tab near the top of the
rod and use a SS machine screw to fasten the wire with a ring terminal and
then "form up" around the top couple inches of rod and fill the form with
epoxy selected for minimum vapor penetration. A small hand modified paper
cup would make a good form. I have seen telephone repairmen put a phone
wire splice in a small baggie (like a sandwich bag) and pour in epoxy,
holding the assy just so to keep the splice near the center of the glob of
epoxy till the epoxy started to cure.
Meanwhile as we await enlightenment regarding "bury the clamp 6 inches" I
will be welding SS tabs near the tops of ground rods and using SS machine
screws to fasten the terminal with ground wire and leaving the connection a
few inches above grade. I will monitor the condition of the connection and
if it looks necessary I will clean up the connection, refasten, and
weatherproof with a good coat of GE RTV or other weather proofer. In the
past I tried anti-oxidation pastes on the copper wire and the terminal prior
to crimping and I think soldering the terminal is better than crimping with
or without using the anti-oxidation paste.
Patrick AF5CK
-----Original Message-----
From: Gene Smar
Sent: Sunday, May 05, 2013 2:11 PM
To: Patrick Greenlee ; TOWERTALK@contesting.com
Subject: Re: [TowerTalk] Grounding HDX-555
Patrick:
I would not bury a mechanical ground clamp. It can't easily be checked
and retightened each year. I would use a longer ground rod and leave six
inches or so above ground and apply the clamp there. A welded connection
such as Cadweld can be buried and forgotten. My 132 feet or so of #2 solid
ground wire is attached to 12 copper ground rods with that method.
73 de
Gene Smar AD3F
----- Original Message -----
From: "Patrick Greenlee" <patrick_g@windstream.net>
To: <TOWERTALK@contesting.com>
Sent: Sunday, May 05, 2013 2:59 PM
Subject: Re: [TowerTalk] Grounding HDX-555
While on the grounding topic... why do some sources recommend burying the
wire clamp to copper ground rod connection a minimum of 6 inches?
Patrick AF5CK
-----Original Message-----
From: Alan NV8A
Sent: Sunday, May 05, 2013 1:39 PM
To: TOWERTALK@contesting.com
Cc: Brad Hyde
Subject: Re: [TowerTalk] Grounding HDX-555
On 05/05/13 12:19 pm, Brad Hyde wrote:
I am in the process of erecting an HDX-555. I have the hole dug and most
of the rebar cage built. My question is about the best method of
grounding. Should I place a copper cable at the bottom of the hole and
then attach it to the tower? This method would have the cable immersed
in the concrete which makes me wonder about that much heat going into the
concrete if lightning hits, even if it is just on the edge of the
concrete. The other method I am thinking of would be three ground rods
placed around the tower and connected together and to the tower with
copper strap and/or very heavy copper wire. Just looking for input from
the collective knowledge of this group as I am in a lightning prone area
in west Texas. Thanks.
I have #4 copper connected to each leg of my HDX-555 (with
stainless-steel shims as separators to avoid corrosion), and each
running to an 8ft. copper-clad ground rod about 10ft. away.
73
Alan NV8A
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