Hi, Ms. Mitchell;
The tower provides protection similar to that of a lightning rod on a
house or barn. However, the protected volume under a lightning rod a
few feet tall is often modeled as a cone, sitting on its base, with a
base diameter equal to the height of the lightning rod, but that is not
a good model to describe the protected volume under a tall structure
like a tower. The following is considered more accurate.
If the tower is less than about 150' tall, it provides 90% protection to
ground level objects out to a radius of about 150'; it provides 99%
protection to ground level objects out to a radius of about 66'. Taller
towers provide no additional protection. The radius of protection
provided to other tall structures, like masts, is much less. The volume
of protection may be modeled by the volume under a sphere rolling on the
ground up to the tower, where the percentage of protection is 90% for a
150' radius sphere and goes up to 99% for a 66' radius sphere.
Reference, _Lightning: Physics and Effects_, Dr. Vladimir A. Rakov and
Dr. Martin A. Uman. 2003. Cambridge University Press. This is an
undergraduate text, not too technical , that provides useful
explanations of why lightning does what it does as well as the latest
findings and data from lightning research and information regarding
lightning protection. It is not commonly available at local public
libraries. I borrowed a copy via inter-library loan from U of MN.
In conclusion, I suspect the tower offers small protection from
lightning for much of the neighbors' property, but it doesn't attract
lightning to neighboring structures, either.
Regarding the interference: That is a difficult issue to analyze from a
distance. The fault may be in the amateur radio transmission, but it is
more likely to be in the appliances that do not comply with FCC
standards. That can only be determined by careful tests. The FCC
enforces those standards only when there is a complaint. There are ways
to reduce or eliminate the interference and I suggest you seek
assistance from the amateur radio organization at www.arrl.org. That
organization works to maintain good public relations between hams and
non-hams, for the good of the service.
R. Haines, amateur operator WOØW
Barbara H Mitchell wrote:
>This concerns a problem my neighbors and I are experiencing concerning
>lightening. The houses in the neighborhood are close together (14' between
>houses), all are on water, and most of them have either motor yachts or
>sailboats. My immediate neighbor has a huge ham radio tower - possibly
>illegally. About a year ago, lightening struck a mast on my lift which put a
>huge hole through the boat, a huge hole in my pool deck, and also destroyed a
>large portion of the pool deck foundation. The 'blast' also killed my
>computer, telephone system, and lots of electrical wiring in my house. A
>transformer in front of my house has been struck by lightening several times.
>Last night at a party directly across the canal from me, lightening struck the
>host's sailboat mast, knocking out electronic equipment. All the neighbors
>have had problems with conversations from the ham operator coming through
>intercom systems, computer speakers, etc.
>The owner of the tower has insisted all along that there is an umbrella
>protection from lightening; we all believed him. He is a very difficult
>person to get along with, so confronting him is useless.
>My question is: Is there such a 'thing' as umbrella protection from his
>tower, or is the tower attracting the lightening? Could this be a problem
>with a lack of proper grounds?
>I would really appreciate any suggestions you may have.
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