Generally nice presentation, however, a few nit-picky questions that raise
some issues.
1) The data is presented without sources (this is important, because
grounding philosophies, and requirements, have changed substantially over
the past decades). I always get concerned when someone cites "Bureau of
Standards" or the "NEC" without saying which edition, how long ago, etc.
(Since NBS changed it's name to NIST some time ago, and it was called NBS
for decades before that, you wonder whether they're citing some sort of data
from 1920 (not necessarily invalid, but nice to know).
2) The chart of resistances vs soil types doesn't specify units. It has a
column for Soil Resistivity, but what are the units? The chart also uses
the British terminology ("earthing") and metric units, in comparison to the
previous descriptions, which were in feet. Is this just a collection of
data they scrounged up somewhere?
3) Then, they shift back to some measurement techniques using the Wenner
electrode arrangement. They DO give a reference for the method, although one
would be hard pressed to find a copy of the referenced article from 1915.
They'd have been better off citing a recent (and current) spec on ground
resistance measurement like the IEEE standard, which is at least available
in libraries and from IEEE (for a price). Back to inch/pound customary
units from metric.
4) then on to a nifty scheme using clamp on ammeters, etc. with tables with
no units (are they feet, ohms, meters, or what)
Anyway, nice graphics..
Someone could do a real service by taking the relevant standards, etc., and
creating a ham oriented grounding thing, incorporating the relevant NEC
requirements, describing the bare minimum, the super duper, and all the
stuff in between.
Jim, W6RMK
----- Original Message -----
From: "Pat Barthelow" <aa6eg@hotmail.com>
To: <towertalk@contesting.com>
Sent: Sunday, February 06, 2005 7:17 AM
Subject: [TowerTalk] Comprehensive Grounding Tutorial on Web
> Folks,
>
> Many of us really appreciate the great exchange of knowledge and wisdom
of
> grounding techniques and tips...It is interesting to see the variety of
> opinions among wise men to the topic.
>
_______________________________________________
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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