[BC] Lightning and grounding ... fun for all!

[Phil Alexander]

On 18 May 2005 at 12:59, Lamar Owen wrote:

> Is making our towers into 'very-reluctant strike receptors' not the goal of 
> Lightning Prevention?  Redirect the stroke elsewhere; maybe set up a 
> less-reluctant strike receptor (using a ball or something) on a special 
> structure designed to withstand the strike, perhaps?  The question would 
> ultimately boil down to 'how large is a "vicinity"?'

Even if you built a strike receptor, it's hard to be sure a fickle stroke
won't come your way and ignore it. I believe there is a corollary to Murphy's
law that says lightning is attracted by the most expensive equipment in the
plant. <g>

As to what is a "vicinity," the usual method is a 30 meter virtual rolling 
sphere projected rolling over the protective terminals and steel structure.
All beyond that bouncing ball is considered unsafe. Another thing to consider
is side strikes from the grounding conductor, whatever is used for that.

Phil Alexander, CSRE 
Broadcast Engineering Services and Technology 
(a Div. of Advanced Parts Corporation) 
Ph. (317) 335-2065   FAX (317) 335-9037




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