> The condo blocks have very extensive lightning protection on the roof
> etc. I don't want to compromise this and, worst still, attract
> lightning into the shack!!!!
>
> What should I be doing with the 75 ohm feeder coming into the shack
> (on the 10th floor) when not in use? Should I earth it? If so how
> good an earth will I need (best I can do is a 5m run to a Cu water
> pipe)?
Water pipes are next to useless for lightning protection Peter,
although they do make excellent safety grounds. It takes a large
mat with multiple grounds to establish a really good lightning
ground.
There are also gimmicks like whiskers that do nothing to reduce
strikes, unless mounted on airplanes that are flying through storms.
The best procedure is to ground the feedline to the building ground
system at the point where the feedline enters the building, and
disconnect it at that point where it comes into the house when not
using it. This is also the recommended procedure for single-family
homes.
All cables and plumbing.... telco, CATV, power mains, water
lines....should be grounded at one point at the entrance to the
structure if possible. That insures any current routes itself to the
building ground, which hopefully is sufficient. It helps insure
everything inside the structure rises at the same rate to the same
potential, so no current loops through things inside the building.
It appears your best defense is to ground the feedline to the
building ground OUTSIDE the building, and disconnect it before it
enters the building if possible.
73, Tom W8JI
W8JI@contesting.com
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