From: "Tony (remove \"_\" from email address)"
Subject: Info on protecting UTP network / phone / AC mains so lightning on cable doesn't destroy everything (again)?
Date: Tue, 05 Nov 2002 10:52:57 +1000
X-Newsreader: Forte Agent 1.92/32.572
I'm just getting back on air after lightning somehow got into my cable and blew
out my cable modem, NIC, printer, CDRW, related ports etc (PC still goes except
for the lost ports, but who knows for how long). It seems dozens of neighbours
suffered the same or worse fate, too.
I therefore want to define a substantial ground plane, say at a network hub,
which all network lines, AC mains, phone and other I/O pass over and get clamped
AC mains are easy - MOVs and some X/Y filter caps (maybe I'll add some common
mode and series mode chokes too, and maybe even a brownout relay to drop it all
out if the AC volts sag too much. And of course I'll make it safe for humans
Phone protection I assume is gas arrestors in parallel with TVSs; but what
ratings are reasonable? and do I need resistors, fuses or PTCs between them?
Network is harder - at 100Mb/s I don't feel I can put anything much across
without affecting the signal. Maybe shottky diodes clamping to a grunty +/-
Cable is harder still - I can't imagine any way to protect it, but I am content
to lose the cable modem if another strike occurs, as long as I can reduce the
probability of losing other equipment - and of course I know there's nothing I
can do about a direct hit (c'est la vie).
All suggestions would be welcome.
PS sorry for the cross post, but the subject seemd relevant to all 3 groups.