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Re: [TowerTalk] [Bulk] Antenna to Shack Ground Connection

To: towertalk@contesting.com
Subject: Re: [TowerTalk] [Bulk] Antenna to Shack Ground Connection
From: Jim Lux <jimlux@earthlink.net>
Date: Mon, 02 Feb 2015 19:57:23 -0800
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
On 2/2/15 10:15 AM, Mike Fahmie via TowerTalk wrote:
Fortunately, wiring used in lightning protection does not have to carry 
sustained current so the thermal mass of the wire can be used as a thermal time 
constant to increase its carrying capacity.
Using "Lightning and Lightning Protection", 1979 as my reference, the impulse 
carrying capacity of #6AWG copper wire is 200 KA for 300 microseconds, fusing at 300 KA 
in the same time.  The same text states that 99% of strikes are less than 60,000 amperes 
and with shorter durations.The Codes may require heavier wire, but it seems that 4 or 6 
AWG is sufficient for most eventualities.
-Mike-


you can look up the Preece or Onderdonk equations too..

Large diameter wire is required for mechanical reasons: it won't get broken accidentally, or it's strong enough to resist physical damage from electromagnetic forces.

a 10 turn coil of AWG10 about an inch in diameter explodes with a fast 10kA pulse (see "quarter shrinker")



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