>>Lightning will take any path, conductive or not, particularly if there's
something solid (like PVC) to guide it.
Well, not exactly... Lightning is electricity. It requires a conductive
path. It passes through the air when the electrical stress caused the
nitrogen to break down and ionize (associated with partial discharge, or
"corona"). I've never seen it hit PVC, unless it was badly contaminated or
contained conductors. I could be wrong, but I used to do a lot of high
voltage testing, and designed 150 kV insulators and bushings.
HP used to make optical isolators for hooking Ethernet between buildings,
that let you run twisted pair. You could also tie all the buildings to a
common ground point, but that's way too much work.
Ken Elliott
=====================
-----Original Message-----
From: slug@nks.net [mailto:slug@nks.net] On Behalf Of Paul M Foster
Sent: Monday, July 19, 2004 1:22 AM
To: slug@nks.net
Subject: Re: [SLUG] Using old ethernet wiring?
On Sun, Jul 18, 2004 at 11:27:30PM -0400, Eben King wrote:
> On Sat, 17 Jul 2004 wchast@utilpart.com wrote:
>
<snip>
> > I used this same setup to pull 300 feet of cord through PVC piping
> > between two houses then pulled cat5 through it. Needed the lub
> > though as it got a bit hard about 3/4 of the way through. But at
> > least I have the two buildings linked.
>
> Shouldn't put something conductive between buildings. They might have
> different ground potential (it works, thus disproving that), or
> lightning could strike nearby, frying one or both ends and attached
> equipment. You should use fiber or radio.
That's why you run a ground wire along with the cable and tie it to the
grounding system at both ends. ;-} (I know, there could still be
differences, even if the ground is a continuous loop between buildings.) Or
you could bury it (best idea, but still not perfect).
And if lightning strikes nearby, it won't matter if it's conductive or not.
Lightning will take any path, conductive or not, particularly if there's
something solid (like PVC) to guide it. Conductive solids only present a
more enticing target for lightning.
Paul
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