[TowerTalk] Need Help For Cable Runs To Tower

[Eugene Jensen]

Drilling holes in conduit for drainage is not a good ideal. It going to be full of water in time. As long as your trench is 18 " or deeper you could use  UF #6-2 with ground  to keep the voltage drop under 3%. And the run your control/Rf cables in the same conduit, It you using hard line just bury it in the trench. 73 and good luck with your tower project. Gene AA4VX

-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of Joseph or Ruth Patrick
Sent: Saturday, May 25, 2013 1:08 PM
To: Jim Lux
Cc: towertalk at contesting.com
Subject: Re: [TowerTalk] Need Help For Cable Runs To Tower

I agree with Jim. It is not code to put high voltage and low voltage in the same conduit. That being said a lot of people do, but don't do it. I live in Florida where the water table can be 18" down or more depending on location. We do not drill holes in the bottom of underground conduit. Again Lot's of people do. This is JMHO. I do not claim to be an expert. Good luck.
 73 DE K4XZ Joe Patrick
God Made Man
Sam Colt Made Them Equal 




________________________________
From: Jim Lux <jimlux at earthlink.net>
To: towertalk at contesting.com
Sent: Sat, May 25, 2013 11:47:44 AM
Subject: Re: [TowerTalk] Need Help For Cable Runs To Tower

On 5/25/13 8:36 AM, Wayne Willenberg wrote:
> While I am waiting for my 89’ crank-up tower to be built and 
> delivered, I thought I would get busy running the various control 
> lines for the rotator, the AC power for the motor that lifts the tower 
> and, of course, the RF cable for my antenna that will be on top of the tower.
> 
> I would like to place these lines underground from the panel entrance 
> to my shack to the base of the tower.  (That total distance is about 
> 175 feet) My first thought was to run the cables through PVC pipe, and 
> to use Andrew LDF5-50A Heliax (7/8”) for the RF cable.  Of course, I 
> will have to use a flexible coax from the base of the tower to the top of the tower.
> 
> I would really appreciate some advice before I start trenching.  For 
> example,
> 
> 1)  It would seem logical not to put the RF cable in the same PVC pipe 
> as the 220 VAC wire for the motor and the power and control lines for 
> the rotator.

And combining power lines and "Class 2 power limited" low-voltage circuits in the same conduit/enclosure/etch is specifically prohibited by most electrical codes.



If it is better to separate the RF cable from the other lines,
> how far apart should the 2 PVC pipes be?
They can be next to each other.  the concern isn't electrical, it's mechanical: 
in order for there to be an inadvertent short from power circuit to "low power" 
circuit, you'd have to have two barriers fail (i.e. conduit walls).

You can combine the coax and the low voltage control lines in one conduit: 
they're all "power limited" circuits.

> 
> 2)  Should I drill holes in the bottom of the PVC to allow any water 
> that gets into it to drain away?

That's a subject of much discussion and subject to local conditions, like whether the animatronic owl needs to be periodically reoriented as the Earth's spin axis changes.

I don't drill holes in mine, but I live in relatively dry Southern California, and I make sure the stub up ends at least a foot above ground surface (so that sprinklers, and such don't wind up putting water into the it). Mostly when I pull the wires out, they're dry, but every once in a while they're damp.  The only time I had "wet" (as in the conduit was full of water) was when there was a shovel and big rock induced break in the conduit that I didn't catch early on.


> 
> Thanks as always for your help with my first tower.
> 
> Wayne, KK6BT
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