[TowerTalk] Tower guy wires / EHS size

Dale Martin kg5u at hal-pc.org
Wed Apr 25 11:23:42 EDT 2007


 
Thanks, Frank. Good info. 

I'm still curious, though.  Is there that much slack in 1/4" EHS tensioned
to 400 lbs. -- 10% 3/16" strength?  Is it the weight of the cable
introducing a sag that 400 lbs. tension cannot remove that wears away at the
hardware?    
73,
Dale

> 
> Dale,
> 
> Using 1/4 inch EHS rather than 3/16 inch EHS will not be a problem.
> 
> Initial guy tension is normally set at 10 percent of its 
> published breaking strength, with upper and lower limits of 
> 15 and 8 percent.
> 
> Guy wire tension less than 8 percent places excessive wear on 
> guy attachment hardware as the guy slackens and tightens 
> repeatedly during wind events.  There have been many 
> documented cases of guy attachment hardware failure as a 
> result of excessive wear caused by inadequate guy tension.
> 
> Guy tension is excess of 15 percent of breaking strength 
> reduces the useful load capacity of the tower by placing 
> unnecessary vertical loads on the tower.
> 
> 73!
> Frank
> W3LPL
> 
> ---- Original message ----
> >Date: Tue, 24 Apr 2007 13:04:03 -0500
> >From: "Dale Martin" <kg5u at hal-pc.org>
> >Subject: Re: [TowerTalk] Tower guy wires / EHS size
> >To: <K7LXC at aol.com>, <towertalk at contesting.com>
> >
> > 
> >
> >I'm curious, Steve, where 1/4" EHS is used in place of 
> recommended and 
> >spec'd 3/16" EHS, does one tension the 1/4" EHS to 400 lbs. as one 
> >would do with 3/16" or to whatever tension 1/4" is rated for?
> >
> >Looking from another aspect, is the 400 lbs. tension specified when 
> >using 3/16" EHS on a Rohn 25g based on the tower type/heighth where 
> >3/16" EHS conveniently has a stength of 4000 lbs and the 400 lbs 
> >tension is just right for the tower?  Or should the tension 
> be 10% of 
> >whatever guy wire size strength is being used...e.g., 670 
> lbs. based on 1/4" EHS strength of 6700
> >lbs.?   
> >
> >73
> >Dale, kg5u
> >
> >   
> >>  
> >> In a message dated 4/23/2007 9:03:02 A.M. Pacific Daylight Time, 
> >> towertalk-request at contesting.com writes:
> >> 
> >> >  I am in the process of erecting a few towers at the new
> >> QTH  and have
> >> > a guy
> >> wire size question.   Two of the towers will be  Rohn 45 @ 
> >> 100' and the third
> >> will be Rohn 25 @ 100'.  They will all  have multiple yagis at 
> >> various heights on them, so not just a top mounted 
> antenna.  The Rohn 
> >> book indicates that each tower should be guyed at  three 
> elevations 
> >> and the bottom two guys should be 3/16"  EHS.
> >> 
> >> >  QUESTION:  I have LOTS of 1/4" EHS and guy  grips.  Is 
> the 3/16" 
> >> > mandatory
> >> to
> >> meet the specs (as in the 1/4" is  too heavy) or - is the 3/16" 
> >> simply suggested (as in the 1/4" is not  necessary but acceptable)?
> >>  
> >>     While the LXC Prime Directive to "DO what the 
> manufacturer says" 
> >> still applies, what you're proposing is a little bit of  
> >> over-engineering (which is not discouraged, BTW).
> >>  
> >>     The capacity of any tower is a function of its  leg 
> strength. By 
> >> using bigger guys you'll be putting more compression on 
> the  legs but 
> >> at the heights you mentioned, it's not a big deal. 45G will go to  
> >> 300' and 25G will go to 200' so you're not overstressing anything.
> >>  
> >> Cheers & GL!
> >> Steve     K7LXC
> >> TOWER TECH -
> >> Professional tower services for hams
> >> Cell; 206-890-4188
> _______________________________________________
> 
> 
> 
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