[TowerTalk] Single Point Ground

[James C. Garland]

Dave,

My QTH has the service entrance to the house located immediately adjacent to
the exterior coax entrance panel outside my station wall. All grounds,
including the house 240V service ground, the rebar cage for the house
foundation, the ground system of the tower (about 130 ft distant), and each
of my three operating desks are tied together at that one point. 

The idea, of course, is that if lightning strikes the tower, all the grounds
will rise together in voltage during the strike, and since they are all tied
together at only one point, damaging strike-induced ground-loop currents
cannot flow between different grounds. 

I don't see any problem with your routing your service ground indoors,
provided your tie point is sufficiently well grounded to absorb currents
flowing from your tower. The only reason to route the service ground
outdoors to your tie point is if you think enough current would ever flow
through the wire during a lightning strike to heat it up and set fire to the
house. Since strike currents will come from the antenna and not the
underground cable from the service transformer, that seems a rather remote
possibililty.

73,

Jim W8ZR


-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of Dave
Sent: Sunday, June 10, 2007 8:27 AM
To: towertalk at contesting.com
Subject: [TowerTalk] Single Point Ground

I am in the process of building my station at a new QTH and have a question
about the single point ground.
I will initially be installing a Steppir on a Trylon 70' tower which is
about 170 feet from the proposed shack. 
The shack will be in a walkout basement room. The entry panel will be
outside of this area. 
The house is serviced with underground power and phone. The nearest utility
pole is about 800 feet away. (above ground)
The utility power entry is located about 65 feet away on the opposite end of
the house from the shack. The utility uses a UFER ground.

How should I tie/route the utility ground to my single point ground. Does
the tie wire need to be routed outside and buried or can it be run through
the structure or a combination of the two? (concrete driveway and sidewalks
in the way outside)

Cheers, Dave - N7DRK

       
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