In a message dated 3/29/01 8:15:55 AM Pacific Standard Time, wa9wsj@yahoo.com
writes:
> I'm planning my tower systems, (two), and would like
> to learn the best method for cable terminations and
> why. Clamps or grips? The cost of materials between
> the two methods is close, so that's not a factor.
> Longevity and SAFETY are! So, what is the collective
> opinion?
Two new towers? Cool.
I can tell from your question that you probably haven't used either
method. Using Preformed grips is THE ONLY WAY TO GO. There is no reason to
use clamps. Clamps take longer to install, you have to bend stiff EHS cable
at every termination (a large pain) and clamp nuts have been known to loosen*
(see below).
Preformed grips go on in a minute or two (really!) and don't need any
additional adjustments or checking. All industrial users like utility
companies use Preformed grips almost exclusively while just about no one uses
clamps anymore. Even if they were a bunch more expensive, the time you save
by using grips makes them worth it.
* Guy cable clamp termination problems come primarily from three areas.
The first is not using enough clamps; most specs call for 3 per termination.
Crosby specs call for 2 but they are different than your hardware store
variety and more costly. Always use 3.
Next, clamps can be installed upsidedown. The saddle of the clamp needs
to be on the live side of the terminination ("never saddle a dead horse").
Backwards installation reduces the clamp holding power by 40%.
Last, nuts and bolts (U-bolts in this case) are subject to temperature
cycling. If you assemble something tower or antenna related, let it sit
overnight and then go back and retighten the nuts. You'll be amazed and
shocked at how loose some of them are. This is true of cable clamps too.
BTW cutting and assembling guy wires takes much longer than you'd expect.
I budget 30-45 minutes PER guy wire so if you've got a bunch to do, it'll
take a day or two. You've got to roll out the guy material, measure it, cut
it and then install the termination hardware and it all takes time.
For cutting EHS, put a wrap or two of electrical tape on the spot where
you want to make the cut and use a hand-grinder or skilsaw with a metal
cutting aggregate blade to make the cut. The tape'll keep the strands
together.
Cheers, Steve K7LXC
Tower Tech
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