Make sure that your antenna or unit are not the highest point on the
tower. Also, you should have a grounded lighting rod on the top of the tower.
Here is a very good link on this topic. It is not going to be cheap to do
it right.
http://www.tvtower.com/grounding_and_bonding.html
John
www.mikrotik.com
At 05:42 PM 9/23/2004, you wrote:
To all,
I have one location where I have had a board zapped 3 times by
lightening. It is on a 100 ft tower with a 24db grid antenna. Both the
grid and antenna are mounted about 2 ft from the top of the tower. The
antenna has a lightening arrestor on it. The tower was orginally grounded
with a single ground rod. The guy cables anchor with earth screws like
the power company uses. The board is mounted in an aluminum box. Cat5
cable down into the house.
After replacing the board the 2nd time I added 2 additional ground rods to
the tower.
Boom, crack, popped again!
It never harms the radio card, only the board. So it has to be coming in
from the ground side. It never damaged anything else until this last time
and it also got the guys switch.
I did notice the last time it climbed the tower that it appears that
someone had painted the tower with a silver paint. I don't know if it was
done before of after the tower was put up. The tower was already up when
the current owner bought the house.
My thinking is that the paint may be keeping it from conducting thru the
joints of the tower. Taking the path of least resistance, it goes thru
the board, down the cat5 to a ground some where in the house. Normally
the guywires will take most of the lightening to ground, but the paint is
probably preventing that. I plan on running a separate ground wire from
the ground clamps at the tower base up to the top of the tower and
terminate it to the aluminum box.
I also have 2 other installations within 7 to 10 miles from this area,
both on 100ft towers, and no problems at all. (knock on wood) One of
these sites is on a tall hill where they took a lightening strike that
wiped out other electronics such as copiers and computers, but it did
nothing to the wireless.
Has anyone else had anything similar happen to them?
Thanks,
LaRoy
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