Joe,
Most local electrical codes require 117V electrical wiring to be run in its
own conduit.
The standard for 117VAC voltage drop is 2% max at the business end. There is
a formula to calculate the required wire size vs the max current to be
drawn. Use:
Voltage drop = K x P x Wire Length in Ft. x Current in Amps / Wire area in
circular mils
where K = Specific resistivity in ohms - circular mils / foot K = 11
for
copper at 77-121 degrees F, 12 at 122-167 F.
P = Phase constant = 2 for single phase, 1.732 for three phase.
I have a 385 foot run to the tower motor which requires 20 amps and wound up
with #2 wires. The third wire, ground, is #12.
For everything else, which is most likely DC, you can apply Ohm's law and
figure what size wire you need. My approach is to make it right the first
time so I tend to err up in size.
For the rotator cable, no matter what you are planning, you will probably
wish you had put the extra wires in some time in the future.
GL.
73, Les
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com]On Behalf Of Joe Giacobello
Sent: Friday, September 02, 2005 11:10 AM
To: towertalk reflector
Subject: [TowerTalk] Need Advice on Long Run of Cables to Tower
I am getting ready to install a second LM-470 and I have to run
hardline, 115 VAC, rotor cable and Ameritron remote switch cable from
the shack to the tower. My guess is the total run will be around 500
feet. Since I know a lot of you have already installed runs of this
length, I have the following questions:
1. Do I have to worry about voltage drop for the 115 VAC on a run of
that length? The AC is needed for raising and lowering tower.
2. Do I have to worry about voltage drop for the rotor voltage?
Should I be using heavy gauge rotor cable?
3. I will only need two positions on the Ameritron switch. Can I get
10 conductor cable suitable for both the rotor (8) and the switch (2)?
4. There has been a lot of discussion of running cables in conduit
over the years. What is the consensus opinion on the best way to
do this? My recollection is that some provision has to be made to
allow for the evaporation of condensation. Is it permissible to
run all the cables above in a single conduit?
I know there has been discussion of some of these topics before but
searching the archives is a pretty tedious task. If someone can provide
the information in a nutshell, I'd be most appreciative.
73, Joe
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
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_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
_______________________________________________
TowerTalk mailing list
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http://lists.contesting.com/mailman/listinfo/towertalk
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