Re: [TowerTalk] Comprehensive Grounding Tutorial on Web

[Jim Lux <jimlux@earthlink.net>]

At 09:50 AM 2/7/2005, Martin AA6E wrote:
> Responding to Jim (but not sure which one!) --
>
> You say
>
> "That's why I was thinking that coming up with a suitable peer-reviewed
> document aimed directly at hams would be useful. Not an application
> note from a mfr or sales oriented source; not that information from
> PolyPhaser or ICE isn't useful, but they have an obvious orientation,
> so you'd want independent backup."
>
> This rings a bell.  We are _amateurs_, and while some of us are
> engineers and scientists in real life, very few if any of us are
> professionals when it comes to specialized subjects like grounding and
> lightning protection.
>
> I observe that a lot of commercial and ham literature (PolyPhaser's
> material and most everything on the web) have a lot more philosophy
> than science.  They say to do this and that but don't give references,
> and they're not peer-reviewed.  I can't find statistics about how well
> their equipment has performed in real installations, certainly not for
> hams.
>
> To develop a standard for grounding of amateur radio stations seems to
> be beyond what our economically small hobby can support.  Industry
> practices for cell towers and similar installations may be the best
> we'll ever get.  Those facilities are quite standardized and are often
> built from scratch.


Maybe this gets to the real heart of the situation.  There isn't a really 
good "scope" description for what's needed in such a document.

I don't know that a standard is actually what's required. I think what's 
required is a good compendium or summary of what's out there.  Maybe this 
is something that is (or should be) in the ARRL handbook (which I recognize 
is a gradually revised labor of love, not a rigorously reviewed standard, 
for all intents and purposes).  There's about 3 or 4 pages on grounding in 
the handbook, and a short section referring to a FIPS document, the IEEE 
Emerald book, and Polyphaser literature.  Certainly, the IEEE document has 
lots of references to various and sundry authorities and test data and has 
gone through a fairly extensive review process.  However the Emerald book 
doesn't cover lightning.

And, the ARRL handbook style is, perhaps, a bit too unrigorous for those 
who want to know "why is this being recommended", and to make some sort of 
evaluation as to whether it is "worth it" for your particular 
installation.  It all comes down to some sort of cost/benefit/risk decision 
that we all make, individually, and it is "amateur" radio, after all.  I 
guess what I'm looking for is something more to make informed decisions.

And, of course, the handbook is internally inconsistent.  In the safety 
chapter it goes on about the NEC requirements for wire antennas (AWG such 
and such, etc.), and then later, in antenna sections, it talks about using 
all manner of wire that doesn't meet NEC, particularly for "low profile, 
unobtrusive" installations.  I'd venture to guess that most hams fall in 
the area of "good intentions" and generally avoid "outright dangerous" 
situatons, while still non code-compliant in the formally rigorous sense.

The AWG12 or AWG14 THHN copper wire you get at Home Depot (and probably 
used in hundreds of ham antennas, certainly including mine) is hardly the 
AWG14 hard drawn wire required by the NEC (in fact, the usual house wire is 
about half the strength of hard-drawn wire of the same size)).  Will my 
antenna fall down in a high wind?  Maybe.  Will it do any damage if it 
does? Nope.

What's really lacking is any useful data to make that decision for the 
casual observer.  I think "I" can make those sorts of decisions rationally 
(although some may disagree with me) and defend them because I do have the 
supporting data and analysis, as well as training and credentials, however, 
I don't think I'm a typical amateur either.

> Most of us install radios and antennas where we can, and we don't build
> bonded metal buildings with controlled cable interfaces and all that.
> What I want to know is how I can make the best installation in my
> particular residence with my particular array of trees, utility lines,
> etc. without spending too much money.  It's never going to be easy to
> use a standard developed for an industrial situation.
>
> So I end up with an _amateur_ installation, hopefully using enough of
> standard practices that my station and I will survive the most likely
> environmental threats.  And with some luck, I will even be able to work
> some DX.
>
> 73, Martin AA6E



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