----- Original Message -----
From: "Jim Brown" <jim@audiosystemsgroup.com>
To: <towertalk@contesting.com>
Sent: Friday, July 27, 2007 12:32 AM
Subject: Re: [TowerTalk] Grounding Standard
> On Thu, 26 Jul 2007 23:20:01 -0500, Mike Miller wrote:
>
>>Drawing on what both Carl, KM1H, has suggested about battery cables or
>>other stranded cables, and what Jim, W6RMK, has suggested about surface
>>area, is there any reason that I couldn't make use of the spare 2/0
>>welding cable I've got hanging around in the garage instead of heading
>>off to purchase something else for grounding the tower?
>
> Mike,
>
> W6RMK has given you good advice, but a fair amount of what has been
> written
> on this topic is of questionable accuracy or relevance. I suggest that the
> FIRST thing you should do is download and study the appendix to my
> tutorial
> that talks about grounding and lightning protection. What I've written is
> far
> from the last word, but it is correct, and it will bring things back down
> to
> earth.
>
> http://audiosystemsgroup.com/RFI-Ham.pdf
>
> 73,
>
> Jim Brown K9YC
What I find strange is that the prior NEC grounding codes were sufficient
for decades upon decades. So why the sudden change? Do they qualify their
reasoning? Is it via a "concensus" which is like trying to make sense of
climate change? Or could it be that the NEC must make regular changes to
justify their existence?
I for one dont like one size fits all mandates. What may be correct for
Florida may be severe overkill for Minnesota or Arizona.
Copper eventually disolves in active soils, it will last for millenium in
the desert.
The difference between a 8' and 10' rod may be important in some locations
but in others 2-4' would be adequate. My 8 footers are driven horizontal in
12-24" of poor soil; typical for this granite ridge. The power company has
constant problems in the area with grounding; neighborhood lights dim with
even moderate household inductive or high current resistive loads.
Why should a 40' Rohn 25G for an example be treated the same way as a 2000'
TV tower?
Unless a person is being forced into compliance then IMO common sense should
prevail. There is no mandate to upgrade existing residential grounding; the
term is grandfathering.
When using a 8' x 5/8" copper clad rod and #6 solid copper wire it is always
advantageous to conduct periodic inspections. I wonder how many of us have
perfectly conducting rods?
Stranded and insulated battery or welding cable can be sufficiently sealed
at the ends to provide long life; certainly longer than battery cables in
their usual corrosive enviroment.
The problem with some engineers is that they strive for 100% perfection and
accept nothing else. Ive seen many of that type come and go over my almost
50 years in the RF industry. They never get a product to market or have one
that is not manufacturable.
The successful ones know when to quit computing and hand the product to the
manufacturing engineers.
Carl
KM1H
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