On 5/18/2020 12:28 PM, Art Greenberg wrote:
I am working on the layout for my tower lightning ground system.
I have on hand about 275 feet of #2 bare solid copper. I also have 17 8-foot
ground rods.
A widely accepted rule of thumb is that rods should be physically
separated by 1X-2X their length. That's because there's mutual coupling
between them, that reduces their total effectiveness. A widely used
layout is to first bond the tower to the concrete base to establish a
Ufer ground for it, then start with driven rods radially 1X-2X their
length from each tower leg, continued radially with that 1X-2X spacing
as far as you want to carry it.
An important thing to remember is that lightning is an RF event, so
inductance is far more important than resistance. By having multiple
rods in parallel, we reduce both R and L.
73, Jim K9YC
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