In a message dated 97-04-08 21:34:48 EDT, you write:
> How do we KNOW (proof test)
> the installed strength of our particular connections?
Interesting question. I don't know of any professional company who
does this so it seems to be out of the purview of amateurs. All of the tower
components that we use and install have been designed by engineers and
exhaustively tested by the manufacturers to comply with industry standards
(like the TIA-222). You can bet that there is safe engineering overhead
already added to the specification. That's another reason that justifies the
PE stamp on your tower plans.
> I don't use
> guy grips because the one and only time I tried using them, bought new
> from Texas Towers on guy cable bought new from Texas Towers, a grip which
> APPEARED to be properly installed let loose while tensioning the guy
> with a comealong.
Using the proper Preforms for a guy wire should be a slam dunk for safe
and reliable installation. The Preform design takes in account cable
diameter, inside diameter, rod diameter, number of rods, pitch length, number
of pitch lengths, direction of lay and raw material. These seemingly simple
devices are actually pretty complex. Preformed guy grips have largely
replaced cable clamps as guy wire terminations in most industries because
they're faster, easier and more consistent in their installation than cable
clamps.
I guess my question to your above mentioned problem is what error was
made that lead to the problem? An error was made somewhere.
>
> Does anyone out there test under load both ends of cables they use on
> their towers? If so, to what load and how is the tension applied?
> Obviously we can't test to destruction but how about loading to, say,
> 5,000 pounds of tension on the 1/4" guy wire? Most of us don't have
> comealongs that are safe with that kind of tension, and a failure of a
> guy at that tension would appear to be potentially fatal for the rigger,
> but how else do we KNOW that the installation will hold under the design
> load?
>
See the above comments. The field test that you are mentioning may have
the sole purpose of giving you more confidence in your hardware and
installation abilities. As for me, I will follow the manufacturer's
specifications and try not to reinvent the wheel for industry accepted
hardware and techniques.
73, Steve K7LXC
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