[Elecraft] Lightening damage

[Fred Jensen]

Nearly every direct strike will fry something (or manythings), connected 
or not.  An arc that could involve a kilometer or two probably isn't 
going to be deterred by a meter or so of disconnected coax.  The 
grandson of my Elmer in the early 50's [who now holds his Grandpa's 
call] became a lightning scientist.

His advice:  Very little [if any] electronic equipment will survive a 
direct strike on your antenna.  There are many 10's of thousands of 
amperes dashing around, and lightning arcs very often fork and take more 
than one path in what appears to be random fashion.  For non-direct 
hits, this electrical mayhem all still creates EMP's.  The goal is to 
have everything conductive in your shack to float at the *same* 
potential.  This means bonding everything together. Connecting that bond 
to an earth electrode is problematical.  If you do, that electrode 
should be bonded to the one at the service entrance [which more often 
than not is a UFER electrode in most late 20th and 21st century 
construction].

Disconnecting outside can be helpful in some cases.  However, my good 
friend Tom, K5RC, who operates the Comstock Memorial Station near 
Virginia City NV, with 7 [or so, I haven't counted lately] towers, some 
well over 30 m, notes:  "Lightning will just as likely strike a 1 meter 
sagebrush bush as a 47 meter tower with a 3-el 80 meter yagi at the top."

That said, in the rare times when we had close lightning while living in 
the foothills of the Sierra Nevada, I did the disconnect at the base of 
the tower out back.

73,

Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

On 11/6/2017 4:12 PM, Gmail wrote:
> I’m sure there are others with more expertise on this subject then me, however several texts including the new ARRL grounding book say it may be dangerous to disconnect antenna coax in the house. It should only be done outside.
>    My daughters vertical was hit by lightening and the lightening leaped 5 feet from a cable on the floor to a power outlet.
> Ray
> W8LYJ
>
> Sent from my iPad
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