[TowerTalk] Lightning protection

David Robbins K1TTT k1ttt at arrl.net
Mon Mar 22 18:25:13 EST 2004

> Just think what the power lines are:
> bunch of towers with spikes on the top, prone to attract discharge.
> Yes, long wires, but insulated from the towers, grounded where?
> So they do not form the "umbrella" effect. The "umbrella" has to be an
> metal structure with good grounding. Power lines are not that.

Obviously you do not work with large power lines.  The top shield wires
are normally at the highest point and are connected to either the steel
structure or to a ground wire that runs down the poles for other lines.
The effect of an approaching downward leader on the power conductors is
the same as if they were grounded... charge on the wires is attracted to
the downward moving stepped leader just as it is on the ground and on
the grounded shield wires.  

David Robbins K1TTT
e-mail: mailto:k1ttt at arrl.net
web: http://www.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://dxc.k1ttt.net

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