[TowerTalk] Guy Wire Cable Clamps

[J. Hunt via TowerTalk]

Interesting statement from Rohn:  Rohn "no longer supports" .

I have seen tower failures of sharply bent guy cables about a anchor point, and many other tower failures when people "cut corners" upon installation.
Decades ago - I was taught an old proverb "Never put a saddle on a dead horse".

I only use Big Grips, a bit more costly... but never have seen one fail.

Thanks N 73,
James
ki5dq

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On Sun, 6/7/15, Donald Chester <k4kyv at hotmail.com> wrote:

 Subject: [TowerTalk] Guy Wire Cable Clamps
 To: "towertalk at contesting.com" <towertalk at contesting.com>
 Date: Sunday, June 7, 2015, 2:56 PM
 
 
 It's tower and antenna season once again.
 
 For tower guying I prefer Big Grips, but for some applications I still use old fashioned cable clamps, for example, to attach guy wires to ground anchors, allowing for easy re-adjustment as necessary, months or even years after the initial installation.  Another is for strain insultors and other hardware whose contour won't allow it to fit snugly against the U-shaped bend of the Big Grip. An engineer at PLP verified that this has caused failure,
 particularly with offshore manufactured strain insulators. He strongly recommended against using Big Grips for such applications, knowingly discouraging potential sales.
 
 For a recent project I ordered a bag of 3/16" clamps from Rohn through one of their distributors, under the same part number as listed in the Rohn catalogue. Originally, these were part # 3/16 CCM, but the Rohn catalogue now lists them as 3/16 CCF.  The old style were "malleable", while the
 new style are said to be "forged".  I have found the newer style to be all but worthless.  One would be better off buying cheap wire rope clips from Ace Hardware.
 
 The older CCM clamps had a deep channel in the body of the saddle, which positioned the dead end to overlay the live cable under pressure from the U-bolt, so that all compression was exerted between the two sections of cable. Instead of a real channel, the newer CCF clamps have four bumps on the body of the saddle, laid out in a rectangular configuration. The channel formed between the bumps is too shallow to hold both segments of cable in place so that one rides on top of the other; the dead end tends to ride over to one side at about a 45 degree angle, wedging partly against the body of the saddle instead of pressing 100% against the live cable. In addition, the older clamps had a series of diagonal grooves at the bottom of the channel, designed to grip the cable over the full length of the channel.  The newer ones have a single diagonal ridge, which pinches the live cable in exactly the same manner as the U-bolt does when clamps are installed the
 wrong way and the U-bolt b  ears down on the live cable. I did a test run with some newer clamps, a piece of scrap cable and a come-along. I was able to pull the cable tightly enough to cause it to slip through three clamps with the nuts firmly tightened. I suspect this would have been impossible with the older clamps; some piece of hardware would fail or the cable would break before it would slip through the clamps.
 
 Furthermore, the U-bolts that come with these clamps are no better than the saddles.  The older ones were heavily galvanised, like marine hardware. The newer ones are merely zinc-plated, just like the aforementioned Ace Hardware product. About six months ago I used some of the newer
 clamps for a less critical application, to attach some pieces of guy cable anchoring the end insulators of a wire antenna. Now, in little more than half a year, the U-bolt nuts are completely rusted with no remaining sign of zinc plating at all; in fact the nuts on these clamps are already rustier than the older ones on a nearby tower that has been up for more than 30 years.
 
 I called this to the attention of a Rohn engineer, and his only comment was that Rohn "no longer supports"  the use of cable clamps with guy wires; they now solely recommend Big Grips. He said they only list clamps in the catalogue because they still occasionally get orders for them. The illustration in the catalogue clearly shows a picture of the older style clamps, not the junk they sell now.
 
 Does anyone know of a vendor who stocks original style heavily galvanised clamps similar or identical to the older 3/16CCM? Based on what I paid in 1980 and on-line inflation calculators, these should now run a little over $1.00 apiece.
 
 Don k4kyv
     
         
           
   
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