John Harden, D.M.D. wrote:
>I have had up a 100 foot 45G tower since 1993. It is festooned with
>monobanders from 80 – 10 meters, and at the 30 foot level a larger bundle of
>Heliax, RG-213/U, and multiple control cables leaves the tower. This bundle
>runs about 50 feet in the air to my upper deck which is at the same height.
>From here it goes up to the shack on the 2nd floor.
> .
> .
>
>
> .
>Typically it is prudent to have the wires come down to the ground level and
>to ground all shields and run the bundle underground to the shack because of
>RF issues.
>
>
>
The real reason for not having the wires exit the tower at any place
other than at the bottom is for lightning protection. A lightning
strike on the tower may decide to run down the wires exiting the tower
at a point above ground. These wires are also more subject to side
flashes. At the very least there will be much more current flowing down
these cables because the point on the tower where they exit will be a
higher potential than a point at ground level.
Jerry, K4SAV
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