Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!bbn!oliveb!pyramid!leadsv!practic!vlsisj!davidc
From: davidc@vlsisj.VLSI.COM (David Chapman)
Newsgroups: sci.electronics
Subject: Re: Lightning protection
Summary: filtering is not lightning protection
Message-ID: <15337@vlsisj.VLSI.COM>
Date: 3 Oct 89 02:31:55 GMT
References: <11561@burdvax.PRC.Unisys.COM> <7600025@hp-lsd.COS.HP.COM> <1827@jato.Jpl.Nasa.Gov>
Reply-To: davidc@vlsisj.UUCP (David Chapman)
Organization: VLSI Technology Inc., San Jose, CA
Lines: 23

In article <1827@jato.Jpl.Nasa.Gov> morris@jade.Jpl.Nasa.Gov (Mike Morris) writes:
>Anyway, due to his experience, I compared the guts of a Tripp-Lite Isobar,
>and the common "surge supressed" outlet strip.  There are several heavy-duty
>toroidal chokes and capacitors in an Isobar, vs 3 metal-oxide-varistors in the
>cheapies.  in fact, I recently found a bunch of 140v MOVs in surplus and added
>them to the standard strips I already had.  The Isobar is also built with 
>good components, and put together like the proverbial tank - no snap-together
>plastic here - it's all metal and screws.

The chokes and capacitors are for filtering, not for surge protection.  They
keep RF energy from getting in through the power lines.  Neither one would
dissipate much of the energy of the lightning strike (in fact, they would
store it for later delivery :-).

They might help if the strike were far away and all you got was a very short
and sharp spike, but then again so would the MOVs.  If you don't have MOVs
in your outlet strips, you'd better have insurance.  Ditto for a surge
suppressor on the incoming phone line.  And back up your data regardless...
-- 
		David Chapman

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