Picture this:
You have 90 ft of R25 assembled and anchored at the base.
You lift the top 5 ft. Imagine a horizontal "rope" pulling on the top
towards the base. The tower weighs 300 to 400 lbs depending
on the weight of the lights, wires, guys etc. To hold the tower
5 ft up will require a rope tension of ( 90 / 5 ) X 200 lbs = 3600 lbs.
The BASE must also be able to withstand this *horizontal* force,
or more.
3/16 inch EHS guy wire is rated at 3990 lbs breaking strength.
You would have ZERO safety factor.
Also, since your pullers will be on the ground, the pull wire will
NOT be horizontal, but sloping, further increasing the needed
tension so you would need to go to a heavier pull wire.
You couldn't get enough people to create the needed pull.
Even if you attached the pull rope to a vehicle, imagine
what would happen if the cable SNAPPED. You would
KILL or SERIOUSLY INJURE anyone who happened to
be in the path of the wildly flying wire. What if the tower
buckles?
The ONLY way to safely pull up an assembled 90 ft tower
is from an ELEVATED LIFT POINT such as a CRANE
or another STURDY structure.
Call Preformed Line Products Company in Cleveland Ohio
for their catalog on Preformed "Dead Ends".
Cable clamps need to be PROPERLY installed or they can
FAIL. You MUST go back and forth, tightening each side
alternately until you achieve proper tightness. Then come
back and do it again after a day or two of temperature cycling.
The SADDLE (body) MUST be applied to the Load Bearing
side of the wire with the U clamp over the folded over loop.
To be safe, you really need 3 properly installed clamps per
termination. NOT a job for 'amateurs'.
For your temporary installation, a Rohn Base Plate resting
on a larger block of 4X4's should suffice with proper installation
measures.
To ensure a SAFE installation, you REALLY need to have
someone supervising who UNDERSTANDS towers and their
installation. K7LXC and W7NI come to mind for the NW USA.
GL, Tom N4KG
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