----- Original Message -----
From: "Pete Smith" <email@example.com>
To: "Frank Donovan" <firstname.lastname@example.org>; <email@example.com>
Sent: Sunday, January 16, 2005 9:25 AM
Subject: Re: [TowerTalk] There's 'ground', and then there's 'ground'
> Fascinating, Frank. I tried going back up the URL tree, and eventually
> found myself at a page for Presbyterian gun owners! However, beginning at
> least with /ground2.htm there's a lot of good stuff there.
> The quoted info puzzles me, though -- my old farmhouse has lightning rods,
> and the cable between them and from them to the ground rods placed at
> intervals around the house is roughly 3/4 inch diameter aluminum, made
> many ~#14 strands that are braided in a fairly complex pattern. It is
> quite flexible and easy to work with.
> When I went looking for home lightning rod suppliers on the Internet, it
> appeared that all vendors for this kind of service are still selling this
> braided aluminum stuff, and only this.
> I guess I'm perplexed -- if it doesn't conduct lightning well, how can
> these people continue to sell it and stay in business? I'd think their
> liability headaches would be phenomenal> >
Aluminum is a fine conductor, and cheaper (for a given current carrying
capacity) than copper. The notorious problems with aluminum wiring in
houses are more to do with installation practices and terminations, not the
wire itself. Virtually all power transmission lines use aluminum as the
conductor (over a steel core), including the lightning protection wire above
them all. So, aluminum, if properly installed, isn't inherently a problem.
As for the braiding, while it's not ideal, perhaps it's "good enough" to
keep the building from burning down (which is the goal of most lightning
protection) as opposed to preventing your equipment from being damaged by
And, don't forget the economic dimension... in theory, you don't want to
spend more on the system (and installation labor) than the statistical
expected return. For example, if the probability of lighnting hitting your
house is, say, 1:10,000 in any given year, and if no protection were done,
the damage would be $100K, then the economic value of the protection is only
$10/yr.... Here in Southern California, nobody has lightning rods on
their houses. Lightning is just too rare to justify the expense.
I grant that you (and many others, including myself) will gladly pay much
more than that to transform an unlikely huge loss into a regular loss of a
small amount (this is what homeowner's insurance is all about, after all).
The other thing is that relatively few houses have 100 foot metal things
sticking up into the air next to them.
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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