Are you running the conductors underground in conduit? If so, THWN-2
(Thermoplastic Heat & Water resistant Nylon) wire is suitable for wet
locations - but not direct burial. Most commonly available THHN wire also
carries the THWN-2 rating these days. Home Depot sells 500 ft rolls in 14
AWG solid for $45 or stranded for $50. Small diameter PVC conduit is cheap
- and you get the ability to service it in the future without having to use
a shovel. Suggest to use the good stuff (stranded conductors & heavy UV
resistant jacketing) for running up the tower - Wireman sells it. Set a
waterproof PVC J-box low to the ground at the tower base and you can mount a
terminal block in it for making the connections.
Just a reminder but don't forget the lightning protection. I mount the
terminal block on a copper clad backboard inside the J-box and shunt each
terminal to ground through MOV's. The copper backboard is connected with a
short piece of copper strap to the tower ground - low impedance is what you
want. To size the MOV's one can do the math to estimate the surge current
by estimating the impedance of the tower and the impedance of the down lead
bundle and then how much surge current you want provide for (MOVs are also
cheap). I do the same at the station end of the cable (important) and
ground it to my common station entrance ground. The idea is to shunt as
much strike current as possible to the low impedance tower ground and then
make sure everything (really everything) in the station is shunted to the
station entrance ground so that it all rises and falls at a common
potential...
Hope this helps give you some ideas.
Good luck on your installation!
Matt
KM5VI
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Dan
Cisson
Sent: Monday, November 11, 2013 6:46 PM
To: towertalk@contesting.com
Subject: [TowerTalk] Rotor wire question.??
I have just installed a M2 2800 rotor at 150 ft...I have about a 185 ft run
to the shack....
I really am having a tough time convincing myself to give almost 1.00 a ft
for what M2 recommends...
The Wireman has the cable for 79 cents a ft...time I go get it., and tax,,
close to 1.00 a ft maybe...
My question to all the brilliant minds out there....There HAS to be
something more readily available that will do
the job that has 4 conductors 16 gauge or better. I have considered 14/3
with a ground,, may not stand up to
the enviroment....I have rotor cable thats smaller gauge,,, But.I surely do
not want to double up on smaller gauge wire and run that.....I wonder if
when D.O.T. runs cable to traffic lights has 4 or more conductors in a
bundle??
Any ideas ?? This would give some good ideas to others....I just hate to
spend nearly 200.00 on a rotor cable !!!!! Dan N4GNR
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