[TowerTalk] Complex Guying Question

[Dick Green WC1M]

Other than optimization, is there any reason to change the tension from 400
lbs? Does the tower sway? Do any of the guys sag too much? 

If not, I would leave the tension at 400 lbs. Why? Tensioning guys to 10% of
breaking strength is the recommendation I've read here on TT most often, so
I would assume that's what tower and/or guy manufacturers recommend (I'm
such a trusting soul when it comes to my fellow TTers!) 400 lbs is a tad
over 10% of the breaking strength of 3/16" EHS (3,990 lbs), which probably
has the lowest breaking strength of the three materials being used. Seeing
as how 3/16" EHS is being used at all three levels, it makes sense to set
the tension to the recommended value for that material.

I suspect that what you really want to know is whether the tension can be
different at different levels, given the different materials. If you weren't
using 3/16" EHS leaders (i.e., if the breaking strength was uniform at each
level), I would guess that it doesn't matter as long as the tension on all
three guys at a give level is the same.

73, Dick WC1M


-----Original Message-----
From: Pete Smith [mailto:n4zr at contesting.com] 
Sent: Monday, May 09, 2011 12:51 PM
To: TowerTalk
Subject: [TowerTalk] Complex Guying Question

I have a 97' Rohn 25 tower mounted on a pier pin.  The guys are at 92, 
61, and 31 feet above ground.  The tower has 2 C-3E tribanders at 69 and 
98 feet, and an EF-240 on a 10-foot mast above the top yagi.  We're in a 
pretty benign wind environment.

Now here's the complex part.  I want to re-tension the guys, which were 
originally set a number of years ago at 400 lb all around, and I figured 
as long as I am doing this job, I should do it better, if possible.  
Why?  Because each guy set is made of different material, and I suspect 
that should/might influence the desired pre-set tension.

The top guys are 6700-lb Phillystran down to about 15 feet above ground, 
and 3/16 EHS below that.  I know it's a mismatch, but I got the Philly 
guy sets cheap.

The second set of guys use Joslyn 21-foot fiberglass power-pole 
insulators on the tower end, and 3/16 EHS the rest of the way to the 
ground.  These insulators are only a little heavier than EHS of the same 
length, but pretty stiff, as you might expect.

The third set are 3/16 EHS all the way, insulated at the tower.

My question is this - what, if any, adjustment would you make to the 
400-lb pre-tensioning value for each guy set?

-- 
73, Pete N4ZR

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