On 5/22/2012 1:56 PM, Mario wrote:
> Hello everybody,
>
>
>
> I plan to erect the new tower. It would be a 60' + 10' mast on the top.
> Currently working on grounding system for station and I came across a lot of
> posts and articles. My initial plan was to bond the tower with the house
> grounding system and entrance point, until I have found W8JI article about
> grounding station http://www.w8ji.com/house_ground_layouts.htm . He says:
>
>
>
> "If the tower or antenna is near the house, it is better to bond it in. If
> the tower if more than 50 feet away, it might as well be isolated on its own
> ground because the impedance will likely be too high to be an effective
> bond."
The problem is, there is no set answer. IE lightning strikes cover a
wide range meaning there is no typical stroke. Rise times and power vary
over magnitudes.
The lower the rise time the closer (electrically) the tower is to the
house. The more powerful the stroke the more power that will reach the
house from a given distance. There is no "practical" distance where
the tower becomes isolated from the house for the entire range of
lightning strokes and nothing will completely protect you from a so
called, "super stroke", but every little bit helps. OTOH there are
systems out there that have the tower at what I consider an impractical
distance from the station with well over 500 feet of coax between the
tower and station. Even then enough charge can make it down the coax to
damage equipment without precautions. Then there is the discussion about
protecting the coax.
I have almost everything connected to everything. I have 32 or 33 8'
ground rods CadWelded(TM) to over 600 feet of bare #2 with parallel runs
to the house entrance grounding bulkhead (Copper was a lot cheaper back
then). I have poly phasers in in line while the coax runs are grounded
to the tower at both the top and bottom. That 100' tower with the top
antennas at 130' has taken many direct hits with no damage. Both
stations run to a single point ground.
I recently lost a Diamond 144/440 duobander which is not on that
system. It was on a 16' mast (give or take) on the North side of my
shop, while I have another side mounted on the 45G at 50 feet or so that
remained unharmed. I do not know what caused the failure or the nature
of the failure. It may be electrical or mechanical. The day before I
noticed it wasn't working, there were some thunderstorms in the area,
but nothing really close.
73
Roger (K8RI)
>
>
> In my case the tower would be 170+ feet away from the house. Just looking
> for other opinions/thoughts.
>
>
>
> Thanks
>
> 73,
>
> Mario
>
> KC8P
>
>
>
>
>
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