Jim Lux wrote:
It seems that the manufacturers of the dissipators are legally very
aggressive, having threatened lawsuits against IEEE and NFPA, among others.
This prompted a more thorough than usual review of the IEEE paper (by
Mousa... google for Mousa and Lightning... it will turn up). Interestingly,
Mousa does say that the dissipators can have a beneficial effect on a
certain class of discharges, but actually makes another kind worse, and,
overall, that you're better off with a well designed conventional system.
Also, for what it's worth, the special class of discharges apparently cannot
occur when the thing being discharged is less than 300 meters tall.
The mfr of the dissipator tried to get a NFPA standard for the dissipators
(as opposed to the existing NPFA 780 lightning rod standards), and when a
huge number (probably every lightning expert in the world) of very
knowledgable people, backed up by extensive research, said that the proposed
standard was, in short, "bunk".
----------------------
And here's the rest of this story:
The controversy over the dissipation theory of operation still rages.
Jim chose this example, but it is a good demonstration of how difficult it
is to realize a consensus
of experts concerning lightning theory.
In 1993 the NFPA (National Fire Protection Association-the authority in the
US concerning
wiring codes) declined to approve proposed NFPA 781, which would have
set Early Streamer Emission standards for a controversial "improved"
type of air terminal (spiderballs), and presumably given the ESE
industry a shot in the arm. ESE makers sued, claiming NFPA 781 had just
as much scientific backing as NFPA 780. In a settlement the NFPA agreed
to have ESE technology reevaluated by an outside panel.
The panel confirmed that there was no scientific basis for NFPA 781. But it
also
said there's no scientific basis for NFPA 780 (traditional lightning rods)
either.
Go figure.
Jon Hamlet, W4ZW
Casey Key Island, FL
"A little piece of paradise in the Gulf of Mexico"
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