[SBE] conversation topic: how often do you check tower ground wires?

[Cowboy]

On Thursday 14 February 2008 12:12 am, Glenn Little WB4UIV wrote:

>  I did lightning damage assessment at a previous job. We used a ground 

>  resistance meter to check the effectiveness of the ground system. 

>  Motorola wanted 5 Ohms or less. I never saw 5 Ohms. About the lowest 

>  I saw was 10 Ohms. You probably need something to reference the 

>  reading to to determine if you have deterioration.


 Just to put this in perspective for those to whom it has not occurred.....

 Let's say you sustain a 3 kilo-amp strike. ( not a big one )
 Let's take Glen's low end 10 ohm ground resistance.
 ( personally, I'll reject anything over about 4 )
 How much strike voltage is available to your 5 volt solid state
 devices ? 
 How much strike current will flow through your "pretty good"
 grounding conductors of, say, FCC number, 2 ohms ?
 Where does the rest go ? How much is that ?
 How many bends ( inductance ) are in those conductors ?
 What frequencies are contained in a strike ?

 How many of us can explain skin effect at an atomic level, and
 how does this affect the R that your 0.4 volt Radio Scrap ohm
 meter tells you, during a strike ?

 Tell me again, why your expensive gear should still function ?
 How many understand what Cris posted ? How many followed 
 the link ? Why not ?
 What if it was a 30 kilo-amp direct strike ?
 Just a few things to ponder.......

-- 
Cowboy

http://cowboys.homeip.net

Kaufman's Law:
	A policy is a restrictive document to prevent a recurrence
	of a single incident, in which that incident is never mentioned.