[TowerTalk] Temporary Guys

[Donald Chester]

I would not consider any kind of fibre rope for temporary guys for several reasons already cited here.  One more danger is the possibility of improper tying.  That happened to me years ago putting up a 25G single handedly.  I used the standard Rohn gin pole, and did everything by the book, except that without a helper, I would  stand on the ground, tie the sisal rope to the  tower section, hoist it up to position from the ground, tie off the rope to a tower rung near the ground, then climb the tower with the section dangling in the pulley and fasten it in place.  This went without mishap until I was at the 100' level.  I had just tied and hoisted a section and decided to take a break.  I  sat down in the shade, and looked up at my handiwork, and to my horror, watched as the tower section tumbled down. Evidently the knot where I tied the rope at the bottom end came loose.  My first thought was that the wayward section would surely hit a guy and the shock wave or broken guy wire would cause catastrophic failure of the whole tower.  Fortunately, it struck only one of the bottom set of guys, and the only damage was a chipped strain insulator.  A rung of the dropped section was bent about 30 degrees, so I discarded it and purchased a new one.  I was glad this didn't happen while I was up on the tower.  I suspect that the only thing that prevented destruction of the tower was the fact that the descent was slowed way down as the falling section was pulling the heavy rope from the ground all the way up through the gin pole pulley and back down again.  From then on, I made absolute damn sure the rope was securely tied and re-checked multiple times at each end before hoisting a section and then climbing the tower.

I have never felt secure on a tower beyond one section above a permanent guy point, so I attach a set of temporary guys to each section as I go up, installing the permanent guys as soon as I reach guying level.  Of course, I use guying brackets and thimbles. I have used #10 copperweld antenna wire for temporaries, along with 3 ea. cable clamps at each termination, and always felt plenty secure.  My tower is a pier pin type, so once I reach the first set of permanent guys at 30', the temps serve to provide peace of mind more than physical safety.  I could read the Rohn installation guide and tower specs many times over, stand on the ground and look at the tower and easily convince myself that it is perfectly safe to climb up 3 sections above a permanent guy point without temporary guys, but once on the tower the first time I feel the tower sway when shifting my weight, I am totally unconvinced.  The temps provide the solid feel and stability that allow me to climb and work with near-perfect ease.  I was never afraid of heights as long as I am sure that the structure I am climbing on is secure.  To reduce the likelihood of an accident by human error, a secure feeling without undue anxiety whilst working at 120' off the ground is just as essential as having the proper climbing equipment and following all the recommended safety procedures.

When replacing or repairing a set of guys, I would never disconnect more than one permanent cable at a time, with the temp already in place before attempting to disconnect the permanent. A calm day is essential as well.  The temporary guy should never be called upon to carry more than a small fraction of the tension expected of a permanent guy wire under all conditions.

Another (non-climbing) near mishap occurred while I was sitting on the ground attaching strain insulators to EHS guy wire.  I followed the Rohn suggestion to use three cable clamps and then "serve" the strands by wrapping each strand of the dead end of the guy round the main guy cable, until running out of strands.  It was a cold, blustery day, and apparently EHS becomes brittle at low temperatures.  After I had attached all 3 clamps, I was "serving" the  strands by manually wrapping them wearing leather gloves, then pulling the final wrap tight with vice grips. While wrapping, one of the strands snapped in two, and a piece about 2" long flew off and hit me right in the eye.  Looking in a mirror, I could see a small dimple on the cornea where the piece hit, but other than discomfort, no permanent damage was done.  But when I examined the end of the strand where the small piece snapped off, I saw that it had separated at a very oblique angle, leaving  the broken end of the guy as sharp as a needle. I was EXTREMELY fortunate that the separated piece hit me in the eye broadside and not at the sharp end!  Needless to say, following that incident, I always wear safety glasses when doing any kind of work with EHS or similar wire. Actually, I would prefer to use the old HS guy cable instead of EHS if they still made it, since it is more pliable and my tower doesn't need the EHS breaking strength. Years later I had to replace some strain insulators, and used Guy Grip pre-forms instead of clamps and serving. They go much more quickly and easily, well worth the additional expense.

Something I don't quite do by the book is adjust guy tension all the way to 10% of breaking strength.  With 3/16" EHS (breaking strength 5000 lbs IIRC) that would mean 500 lbs tension on each guy wire (maybe less if I incorrectly recall the breaking strength), which to me  would seem to unnecessarily load down the tower. I was told by someone that the reason for all that tension is to reduce swaying of the guy wire in the wind,  which can fray the cable as it swivels to and fro over the point of attachment, but using thimbles and guy brackets, the sleeve that fits over the bolt is designed to rotate, so I don't see any increased likelihood of failure.  I tighten the guys until I feel comfortable with the amount of sag, play and feel of the wire, probably somewhere around a couple of hundred pounds of measured tension or maybe a little more.  But I make sure the tension is very close to the same for each guy, and that the tower is plumb at each guy point.  Another must to avoid is tensioning the guys to maximum during hot weather, since they contract during extreme cold, resulting in over-tension during sub-freezing periods in winter.

Don k4kyv

_____________________________________________________________

This message was typed using the DVORAK keyboard layout.

http://www.mwbrooks.com/dvorak/


http://gigliwood.com/abcd/