On Fri, 19 Mar 2010 22:31:32 -0400, Paul Christensen wrote:
>What's confusing is to hear that placement of the secondary protection at
>receptacles will cause an asymmetrical rise of the ground potential between
>branch circuit grounds. I get the theory of that concept but is that what
>really occurs during most surge events?
There are MANY instances of this happening with computer systems and home
entertainment systems, where there is much interconnection of equipment
plugged into different outlets (and surge protectors at different locations).
>I cannot imagine the IEEE and
>respected commercial vendors like Leviton, Hubbell, Square-D, Cutler-Hammer,
>etc. -- all recommending a practice that's counter-productive, even if that
>practice helps them sell more product.
"Respected commercial vendors" are those with a large enough advertising
budget and market penetration for us to recognize the name. I'll give you a
well respected name -- Altec Lansing -- that was sold off twenty years ago to
a company that sells junk products. And nearly every "respected commercial
vendor" of ham gear builds pin 1 problems into their equipment.
More to the point -- the manufacturers you cite primarily sell CONNECTORS and
HARDWARE, much of it made in China, imported as a commodity, and resold. How
many of those companies have EMC engineers on staff? Neutrik is the only mfr
of audio connectors that regularly participates in AES Standards work on EMC.
Switchcraft used to do so, but their engineering is so downsized that I
haven't seen one of their folks for years.
As to the IEEE -- I have the Green Book and the Emerald Book, which are their
Standards on Power and Grounding. Both were written before the development of
series mode surge suppression, and neither of them considers equipment at
different locations that has low voltage interconnections.
Jim Brown K9YC
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