From: Watson 'Atto Parsec' Name
Subject: Re: Info on protecting UTP network / phone / AC mains so lightning on cable doesn't destroy everything (again)?
X-Newsreader: MicroPlanet Gravity v2.60
Date: Tue, 5 Nov 2002 04:05:44 -0800
NNTP-Posting-Date: Tue, 05 Nov 2002 05:06:23 PST
Organization: InReach Internet
In article , "Tony (remove
\"_\" from email address)" talked about...
> Hi all,
> 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
> to (electrically).
> 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.
You can't stop lightning. You could do everything to the PC and the
extremely high currents of the lightning will induce enough current into
some short cable such as the coiled cord of your keyboard, and this will
burn out your computer.
So make sure all your equipment is in good woerking order and that the
already existing built-in lightning protection has not been compromised by
the previous damage.
You might consider adding an isolation transformer to the incoming AC line.
Or else use a good UPS with built-in protection.
Also, the proper place to post for the network cabling is
comp.dcom.cabling. There you will get a stern lecture from the fanatic on
lightning, telling you that the most important thing is proper grounding.
He has a point, but I think he's a kook and a troll. But your hub and NIC
already have protection with a transformer to isolate the signal, and
arrestors to clamp the fault currents to ground. So you don't have to do
anything. Same with the telephone cable. It should have proper protection
and grounding, but make sure this is in working order. It could have been
damaged by the previous strike.
One more point. Your equipment has already served its purpose. Even tho
it failed, it did so without causing a fire or loss of life. So be
grateful that you came thru your previous experience with just a few burned
out items. If you screw around with things, you may not be so fortunate
 Lightning struck a few hundred feet from my place, and I saw the
damage it did. It hit a high voltage line on the top of the power pole.
This cable consisted of 6 strands of #10 (2.6 mm) aluminum wire around a
center strand of steel the same size. The bolt melted 5 to 10 yards of the
aluminum wires into foot long pieces and these were strewn all over the
ground around the strike point. It takes a *lot* of power to do that kind
of damage. So don't mess with Mother Nature!
> PS sorry for the cross post, but the subject seemd relevant to all 3 groups.
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you put NOSPAM in the
Subject: line. alondra101 hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html