On Tue, 7 Oct 2008 07:30:48 EDT, K7LXC@aol.com wrote:
>One of the main reasons for lightning protection is to keep the
>transients out of the house/building so you want them installed
>where the cables enter the house.
Yes.
>
>Commercial installations typically have coax shield grounds at
>the bottom of the tower where the cables transition from vertical
>to horizontal as well. Since your tower is so close to the house,
>I'd put my efforts and money into the building entry.
I'd bond shields at the top of the tower, at the bottom of the
tower, and at the house, and I'd bond the earth electrodes at the
tower to those at the house.
Remember that arrestors like Polyphaser and ICE protect equipment
by minimizing voltage between the shield and center conductor. In
other words, they protect the equipment input. The EARTH connection
diverts lightning current/voltage so that less of it flows into the
equipment.
The cable shield SHOULD be connected to the shielding enclosure of
equipment. If it is not (that is, if the equipment has a pin 1
problem), any lightning-induced current will flow through the
circuitry and likely cause a (destructive) failure. Now, there
could also be sufficient voltage drop across the chassis to cause
problems, but a lot less than on a single circuit trace, or even a
ground plane.
73,
Jim Brown K9YC
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