[TowerTalk] Routing Coax and Control Lines

[Joe Subich, W4TV]

> I would like feedback on the pros and cons of running cables
> elevated versus underground. Thanks in advance.

The only time I would consider elevated cables is if they were
covered by a metallic "ice bridge" (and lightning shield) that
was bonded to lightning ground on both ends of the run (like a
broadcast FM/TV installation).

If a tower takes a direct strike, the voltage will divide as the
ratio of the tower above/below the place the cable exits the tower.
By failing to take the cable completely to ground and bond the
shield to the tower at ground, one can put several KV on the shield
of the cable ... I would not want that even on the shack entrance
panel.

I've seen the damage lightning can do even to well bonded FM/TV
rigid cables where they enter/exit a tower (and once had to replace
branch lines, power divider and a couple hundred feet of 6" line
due to lightning damage) ... the relatively minor effort to bring
amateur lines all the way to the ground is cheap insurance!

73,

    ... Joe, W4TV

On 7/9/2016 11:26 AM, Keith Dutson wrote:
> My tower is located 17 feet from the shack entrance panel (from KF7P).  I am
> replacing all coax with Andrew Heliax.  I have flexible Heliax jumpers to
> run from the tower to the shack.
>
>
>
> All lines are now running underground through 2.5 inch plastic electric
> conduit.  I am thinking of running everything from the tower through
> elevated 3 inch plastic electric conduit mounted to the tower and shack
> roof, with clearance for the mower to cut the lawn.
>
>
>
> I would like feedback on the pros and cons of running cables elevated versus
> underground.  Thanks in advance.
>
>
>
> 73, Keith NM5G
>
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