[TowerTalk] Wire rope clips vs guy cable clamps

[Donald Chester]

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