On Fri, 05 Jan 2007 12:13:37 -0500, Les Kalmus wrote:
>Should be OK, no?
Not ideal. The BEST, by far, is for all cables -- power, antennas,
CATV, telco to enter at the same point so that the ground
connections between them can be as short as possible.
Remember that the MOST important element of lightning protection
is for all of those systems to be at the same potential when a
strike hits. The wires connecting the grounds will carry current,
and there will be both induced voltage and IZ drop across their
inductance. So in the world of lightning protection, SHORT is
Gary Schafer, K4FMX, said:
>A single point ground is NOT a place or spot in the earth but it
>is a point of common connection which can be anywhere designated.
>The whole idea of a single point ground is to have a place to tie
>all lines together with zero impedance between them. You can run
>as many grounds to earth from that point as you desire. But all
>cables entering the shack must be physically mounted to that
>single point ground panel.
AND THAT PANEL MUST HAVE A SHORT BOND TO ALL OF THE OTHER GROUND
BONDS IN YOUR BUILDING -- POWER, CATV, COLD WATER, BUILDING STEEL,
AND LIGHTING PROTECTION. Caps added for emphasis. This is quite
As hams, we tend to focus on our INTENTIONAL antennas, but they
are only one element of the problem. Lightning will see every
other conductor in our home as an antenna, and will induce current
onto each of them based on their length, orientation, and where
they are connected. The telephone line is a very good receiving
antenna for lightning. So is the power line. So is the downlead
from a cable TV system. We ignore them at our peril.
Several of my friends in the pro audio world who have no
INTENTIONAL radio antennas at all have lost all of the Ethernet
and printer interfaces in their home office computer systems from
Jim Brown K9YC
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