Hi Steve!
The high winds have subsided, and no more guy wires -- or anything
else -- have broken (sigh of relief!).
Now for the follow-up maintenance that follows a particularly valuable
inspection this season! During some of the high winds last night, I
certainly paid attention to the significant amount of motion in long guy
wires. This was particularly the case for the guys going to the top of
the 200 foot towers, but there is still significant wind induced motion
even in guys at the 100 foot level.
I've concluded from my broken guy wire experience that its not safe to
terminate a guy wire into a fixed object (tower or anchor) without
protecting the guy with a heavy duty steel thimble. Heavy duty thimbles
are relatively inexpensive and readily available, for example use a Rohn
part number 3/8THH for 1/4" guy wire terminated in a big grip. Most of my
nearly 100 guy wires use this method, but a few do not, including the ill
fated broken guy wire!
Why is the thimble so important? In my case, a 1/4" EHS guy wire was
terminated directly into an AB Chance "Tripleye" guy anchor, Catalog No.
7558. Screw-in anchors commonly have the same "tripleye" or "thimbleye"
opening for attachment of a guy wire. These anchors may be safe on
relatively short utility poles where there is not a great deal of guy wire
motion in high winds, and where guys of 5/16" or larger are used.
However, based on my experience, I now believe it is UNSAFE to terminate
long 1/4" guy wires into this type of guy anchor because inevitably the
guy will move in the fixed guy anhor thimble. Long tower guys should be
terminated in heavy duty thimbles THAT ARE FREE TO MOVE WITH THE GUY WIRE.
Thimbles forged into the guy anchor cannot move with the guy wire and
abrasive damage to the guy wire is inevitable. I do not believe that this
basic abrasion problem can be solved without the use of a thimble ATTACHED
DIRECTLY TO THE GUY WIRE.
Guess what I'll be doing this weekend...
73!
Frank
W3LPL
donovanf@sgate.com
On Tue, 1 Apr 1997 K7LXC@aol.com wrote:
>
> > In hind sight, its apparent that the closest Crosby clip must be close
> > enough to the anchor to prevent the cable from moving in the anchor
> > during high winds! The 12 inches to the first Crosby Clip left the cable
> > free to move in the anchor. I've never seen a spec for the distance to
> > the first Crosby Clip, but -- obviously -- 12 inches was not close
> > enough!
>
> Hi, Frank --
>
> According to my 1994 Crosby catalog application information, the clip
> (cable clamp) should be installed "as near the loop or thimble as possible".
> >
> > I feel fortunate that this 135 foot tower is still standing. Today we had
> > gusts well over 50 MPH, and surely the tower would not be standing today
> > if hadn't been lucky enough to discover the broken guy yesterday!
> >
> Jeez, you're right. All that clean living must help!
>
> Thanks for your recent post on tower inspections. It's amazing what you
> can find before it becomes a problem. Look at it this way, if you do a
> thorough inspection and don't find any problems - congratulate yourself on
> having done a really good job!
>
> 73, Steve K7LXC
>
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