In a message dated 99-07-17 11:16:07 EDT, wa4dou@excite.com writes:
> Anyway, how many of you have, in building or planning low towers, noted
> that Rohn specifies Block no. 4A(Concrete Anchor Data)for all 25G tower
> installations up thru 110 mph,
> and to 100 ft. with 45G in 110 mph wind before they upgrade to 4B.
> I realize that i've heard it said repeatedly over the years that Rohn is
> very conservative in their rateings.I also realize that it can be very
> dangerous to "second guess" Rohn, or to depart from their specs.without a
> lot of knowledge.
> It is easy to look at a 50 or 60 ft 25G tower with 110 mph specs and draw
> a conclusion that Block 3D or 3E would be totally adaquate for anchoring
> purposes. My anchors are GAC25's which are only 5-1/2 feet long as opposed
> to GAC30's which are 7 ft. long. Since i am digging these holes
> with post hole diggers and a shovel, i don't relish digging the last 1 foot
> of depth between 3 and 4 ft. or even to 3-1/2 feet deep. I'd even make a
> concession and pour the concrete 1-1/2 feet deep which is 50 % deeper than
> called for in Block 3D and more than 3E, knowing full well that there would
> be less "earth cover".
> Am i barking up the wrong tree here?
The LXC Prime Directive is to "DO what the manufacturer says". Let me
put it like this - how well are you going to sleep when that big windstorm
comes barreling through knowing that your hole wasn't as deep as the
manufacturer recommended?
BTW Wilson County is an 80 MPH windspeed zone so if you do install
everything for 110 MPH, it'll just be over-engineering which we don't
discourage.
Cheers, Steve K7LXC
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