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[TowerTalk] Tower Drawings & Permits

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Subject: [TowerTalk] Tower Drawings & Permits
From: (Kimo C. Chun)
Date: Thu, 1 May 1997 17:18:00 -1000
I am not on the reflector but thought I'd let you know how it is
here on Oahu, Hawaii.

Though one can assume with some reliability that manufacturers
spec their towers conservatively and if installation guidelines
are followed you can have some peace of mind...our building
department doesn't care.

For a tower to be "type accepted" it must undergo failure testing
to the satisfaction of the department (I have not verified this
but was told this by another). But this does not include the base.

The building department wants the foundation design for the
specific tower and location certified by a licensed engineer
before their review. Obviously, the engineer will review the
tower as well to protect him/herself. Thus we cannot escape
total review by a compensated professional.

The manufacturer's drawings just provide a starting point or idea
for a base design and data for the engineer to do his/her own
calculations. I tried to minimize the bill by drawing plot and
base design plans myself on my computer.

My particular installation was a self-supporting tower with the
maximum antenna load averaged at 10 feet above the tower. The
engineer calculated the tower stress on that basis at building
code max wind speed and exposure factor plus soil factors.

True, other jurisdictions will have their own less or more stringent
requirements. Here, at least they allow one tower per property with
a maximum of 90' with no hassles if you follow their rules. My
engineering costs were around $1000.

I have an interesting antenna setback court decision but that is
another story.

Aloha, 73

Kimo Chun, KH6IFN

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