How many tower erectors, including professionals with years of experience, ever
noticed this discrepancy?
The U-bolt clips/clamps long sold as "guy wire cable clamps", even by major
reputable tower manufacturers like Rohn, are actually manufactured as wire rope
clips. The "lay" of EHS guy wire is the opposite of that of most wire rope
stock. Wire rope is usually "right-hand lay", whereas EHS cable is "left-hand
lay".
"Lay" describes the direction in which the strands are twisted to form the
cable. To determine the lay, look at the cable as it points away from you. If
the strands appear to turn in a clockwise direction (like the threads on a
right-hand screw) as the strands progress away from you, the cable has a
right-hand lay. If the strands appear to turn in an anti-clockwise direction
(like a left-hand screw thread) as the strands progress away from you, the
cable has a left hand lay.
http://www.h-lift.com/wirerope.htm
The grooves in the cable clamp saddle are designed to accommodate wire rope, so
they are laid out diagonally in such a direction as to fit over right-hand lay
cable. With the proper wire rope, the strands fit precisely into the grooves.
With EHS cable, the diagonal grooves in the saddle are laid out in the OPPOSITE
direction of the lay of the cable strands, so instead of fitting precisely
over the cable strands, the grooves in the saddle grip the strands with
brute-force like the teeth on the jaws of a pair of pliers or vice grips.
Remove a cable clamp that has been securely tightened to EHS cable, and you may
see that the wrong-way grooves have left an imprint or even gouged the surface
of the strands.
Since these clamps have been used for decades to clamp guy cable, the wrong-way
lay is apparently not too much of a problem, even though I would think grooves
laid correctly to fit the lay of the cable would grip more securely.
Don k4kyv
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