Leonard Caillouet wrote:
"w_tom" wrote in message
...
People who are more than TV repairmen learn from their mistakes and
correct reasons for that failure. TV repairmen only fix defects -
never bother to learn how those failures can be avoided. Let's have
some fun. Let's reply using the same mockery and insult that Michael
uses. Except this post will be accurate about Michaels intelligence.
I am merely a TV repairman who happens to have quite a bit of education,
and has done much research on the matter. We began installing good
basic MOV based suppression on our clients' systems long ago, using
system level units that protect all incoming lines. We also pay close
attention to proper grounding. What we have found over many years of
this practice in one of the most lightning intense areas of the USA, is
that our systems never take damage. During times of high thunderstorm
activity, however, we see several times the repair volume, and
invariably, the user did not use a surge suppressor. Our clients are
happy with the systems that we sell and with the reliability. There are
good reasons to suspect that system level surge suppressors do work, but
grounding cannot be ignored.
As for you w_tom, you have done far more to clutter groups than to
provide any useful information. While your emphasis on grounding is
good advice, much of the rest of your arguments are out of context and
misleading. Michael may be a crochety ass sometimes, but at least he
consistently provides useful information. Stick to preaching the
importance of grounding and give the rest a break.
Leonard
Thank you, Leonard, for a breath of fresh air in this onerous thread
that w_tom perpetuates ad infinitum. This isn't his first, for newbies
trying to fathom his morass.
I've been a TV repairman. I'm now a "communications electrician" which
means I deal with telephone lines/switches, land-mobile radio, microwave
radio systems, security systems, and the like; in high-voltage
switchyards and substations. We deal with huge surges from switching
transients and direct lightning hits on the transmission lines. I know
first-hand what happens when surges hit. When I said "transmission
lines", I'm talking both from the 60hz side as well as the RF side as
the lengths are sufficient to act that way.
Define "ground" or "earth", Mr w_tom. Have you ever run an ANSI spec
ohms test on one? I think not. I've done grounding for military tactical
radio systems and complete commo systems. What you think is "ground" may
not be ground at all due to soil composition. I've seen ground rod
"farms" made up of 20+ vertical 8' rods on a 10 foot grid come up in the
500 kilohms range when the same rods in the same location would test
lower than 1000 ohms if those same stakes were buried sideways 18" below
surface.
Substations/switchyards have "ground mats" of heavy copper wire in a
grid spacing of 1-2 feet and about 6 feet under everything that's
covered with gravel. It's also cad-welded at all intersections to
prevent corrosion. This ground mat system is also used at well-designed
radio sites. Even with this elaborate grounding system, a major
malfunction at 230KV can create such a voltage differential to induce
fatal "step voltage" between your legs.
http://ballengearry.com.au/papers/St...004_090804.pdf
For 120Vac grounding on our equipment, we try our best to bring all
equipment grounds (racks and cable trays as well) to a single point that
*then* connects to the building's ground as close as possible. We do
have the advantage of most equipment running off DC at 24, 48, or 130
Vdc on huge battery racks that can absorb a lot of surge energy.....