I don’t want to get into a scientific discussion, but the main point about lighting strikes and faraday cages is that the amount of energy in the lighting strike is huge and the faraday cages that we use (ovens, antistatic bags, aluminum foil wrap and even many of the commercially available cages) are not perfect (they have openings, the holes in the net are often too big, they have sharp edges, their grounding is of non-zero resistance etc.).
The combination of these two factors creates a situation where it is a bit of a crapshoot of what would and what would not survive. Having said that, it is probably better to protect these instruments to whatever degree is reasonable (I cannot see anyone carrying a heavy safe to keep a handheld GPS in it). Marek ------------------------------ Message: 2 Date: Fri, 17 Jan 2014 13:21:58 -0400 From: Rich Knowles <[email protected]> To: cnc-list Cnc-List <[email protected]> Subject: Re: Stus-List Electronics GPS Message-ID: <[email protected]> Content-Type: text/plain; charset="iso-8859-1" This is an informative site about Faraday Cages: http://www.princeton.edu/~achaney/tmve/wiki100k/docs/Faraday_cage.html We had them at maintenance shops located at TV and radio transmitter sites to enable interference-free equipment testing in high RF environments. Direct lightning strikes on transmission antennas and equipment were always a crap shoot as to what damage would be incurred. All towers, buildings, cages and protective devices were religiously grounded. Some times they would survive direct hits, and, at other times, damage would occur ranging from catastrophic to minor. Always a surprise. Rich Knowles INDIGO LF38 Halifax, NS.
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