[time-nuts] Thoughts on lightning protection measures....
SAIDJACK at aol.com
SAIDJACK at aol.com
Thu Apr 12 22:28:24 UTC 2012
Hi Attila,
if I remember correctly, the issue is that the "ground" at the house is
not a "real" ground when the earth is frozen, as the resistance of frozen
earth goes up substantially over non-frozen earth. So it's like not having
grounded the wires at all.
This is a real issue for cables brought to the house (cable TV, telephone,
etc etc) as those cables are grounded somewhere else on the other side, and
thus there may be 1000's or even 10000's Volts between the two "grounds",
even (or especially) for just a proximity strike. As mentioned by someone
else, all bets are off anyway's for direct hits, not much will survive a
direct hit.
It's been a long time since I designed cable TV receivers, but the specs
are here, and I think there are some explanations in there somewhere:
_http://www.nordig.org/specifications.htm_
(http://www.nordig.org/specifications.htm)
bye,
Said
In a message dated 4/12/2012 09:54:40 Pacific Daylight Time,
attila at kinali.ch writes:
Hmm? That sounds interesting. In switzerland, and AFAIK in most european
countries, power feeds have to be grounded at the entry of the house
(ie the neutral conductor is grounded). This should protect the electrical
equipment from such ground jumps as you discribe. Or do i miss something?
Attila Kinali
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