[MLB-WIRELESS] Lightning protection?

[Geoff Hammond]

A few years ago, I was building a large (to me) electric fence just outside
the middle of nowhere and used a solar cell at the top of a large (~6m) pole
to charge the battery... Lightning was a concern to me as I figured I had an
excellent lightning attractor. On the day of the erection of this pole, a
guy came along to help who used to install radio antennae in Papua New
Guinea. He had lost many, many installations to lightning until he found a
way, which we used on my solar cell pole.

The pole was 3 inch water pipe and we welded a spike about a metre long to
the top of it. The spike had a point ground at the end which wasn't welded
to the pipe. The pipe was well earthed (three x 1metre spikes into the
ground a reasonable distance apart and connected via leads about the
thickness of the stuff that connects car batteries to car electricals (about
1cm diameter). The really cute bit was that we insulated the solar cell from
the pole by slipping some black polythene pipe over the pole where we
clamped the solar cell mounting bracket. His theory was that there would be
a cone of protection under the spike and that the likelihood of some energy
finding its way through the panel rather than the pole was reduced because
of the plastic pipe.

The installation has taken several strikes, but continues to work just fine.
It might be overkill for the average urban antenna installation, though....
8-)

gah


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