At W7NI's urging, I'll relate a rather embarassing incident that took place
many years ago with a crank-up tower I had in California. A little different
twist, no pictures of guys looking at amputated finger stubs, but maybe this
story will save somebody from serious injury or worse.
I had a lightweight 48-foot crankup tower on which I had a 2-element 40 meter
beam. One pleasant Sunday afternoon, I decided to lower the tower so that I
could safely do some tree trimming. The antenna had gone up quite easily, but
I violated a fundamental antenna erection principal about keeping such devices
away--FAR AWAY--from power lines.
When the beam went up, it was turned parallel to the power lines, providing
adequate clearance. However, when I went to crank the tower down, the antenna
elements were perpendicular to the power lines. And I had failed to allow
adequate clearance in all situations.....when the tower had been lowered about
halfway, about 3 inches of reflector came to rest on the 12,000 volt lines at
the back of the property.
Fortunately, I was wearing gloves while cranking the tower down, otherwise I
might not be writing this today! I let loose of the winch handle, jumped
free of the mass of electrified guy wires that were sparking around my feet,
and watched the antenna fry on the power line until the line finally broke,
fell onto a chain link fence to which one side of the lower section of tower
was guyed, vaporized that guy wire, finally hit a cement sidewalk and melted
some sand in the cement. The tower telescoped the rest of the way down, but
somehow remained standing, even though it had lost one of its lower guy wires.
When I went inside the house, I was greeted by a radio room full of smoke,
fried rotor control box, charred eaves along where the coax was.
The incident also knocked out power to at least 100 houses, as well as to a
traffic signal at an intersection 2 blocks away, and while the power was out
for 5 hours, there was a traffic accident at the intersection due to the
signals not being functional.
When the power line separated and fell to the ground, it also nicked a phone
line, wiping out telephone service to a good portion of the neighborhood. I
was a pretty popular guy around there for awhile.
Lucky? You bet! I should have been fried, the tower should have come down,
the house should have caught fire. The warnings you read about keeping
antennas and towers away from power lines are actually there for a purpose.
Proper guy points aren't a bad idea either.
73 - Phil, N6ZZ
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