[TowerTalk] Setback requirements (was "permit in hand")

[Jim Lux]

jeremy-ca wrote:
> 
> 
>> bill rubin wrote:
>>> Perhaps this will help your case,  Rohn letter stating that tower 
>>> failure is
>>> 1/2 to 1/3 height. see Rohn Letter on Fall Radius of a Guyed Tower at
>>> http://www.antennazoning.com/_mgxroot/page_10748.html
>>
>>
>> That's an interesting letter.
>>
>> Note, however, the "assuming the guys remain intact".. you'd have to
>> show by analysis (or test<grin>) that the guy system's failure point is
>> so much higher than the tower's, that the tower is guaranteed to
>> collapse first.  That might not be a tough hurdle to bear, depending on
>> the system.
> 
> 
> Jim, you are assuming brand new guy wire of the type defined by the 
> tower manufacturer. Ive reguyed towers installed with wire rope and Rat 
> Shack crap for TV masts. Dont expect the building inspector to know the 
> difference.
> 
> Another factor missed by those who dont live near salt water is to have 
> salt laden fog or drizzle that comes many miles inland. Ive walked out 
> of the house on many a morning and couls taste the salt in the fog and 
> I'm 20 miles inland. After 15-20+ years even 3/16 EHS may be the weakest 
> link by far.
> 
> Carl
> KM1H
> 
> 
Which is precisely why the letter from Rohn (and the analysis for the 
broadcast tower) won't hold much water with the local authorities.  They 
too have seen towers guyed with clothesline, and I wouldn't think they 
have much confidence in a homeowner, in general, engaging in a regular 
protective maintenance and testing program.  So, they do the easy thing 
and assume worst case. (especially when it helps with the unstated 
objective of keeping tall ugly things out of residential neighborhoods)

What happens when they realize that a trebuchet (which, after all is 
just a falling tower on a pivot) can throw things well beyond the height 
of the throwing arm. <grin>