[TowerTalk] Need Help For Cable Runs To Tower

[K8RI]

And my two cents from Central Michigan.

Right now (spring) the water table in my back yard is...Ar=t the surface 
and by August it'll be 5 feet down.  I do not drill hoes in the 4" 
conduit and i terminate the conduit several feet above ground in NEMA 4 
enclosure,  20 X 24 X 6 box at the tower,
http://www.rogerhalstead.com/ham_files/cablebox.htm
This shows the original run to the house through the basement wall. This 
was changed to the NEMA box feeding through the end plate after the back 
hoe pulled out a section of basement wall when we had a new septic 
system installed.

I have a photo of the new NEMA box which has been replaced with a larger 
one.  Note, instead of 90s I use a pair of sweep 45s.

So one end opened under the floor , about 18" above grade and the other 
into the NEMA box at the tower.  That in turn has conduit that opens in 
to the shop about 3' above grade.  Before the shop was added the 
original box just had a stub where the cables came out and that was 
filled with the soft expandable foam.

Although I have control wire in the same conduit, it is low voltage. 
The PST61 rotator will receive a 3/4" run of its own as it runs on 110VAC

There are no openings directly to the atmosphere from any of the NEMA 
boxes.  Small cables go through water proof fittings with packing glands 
and coax comes out through bulkhead connectors.

73

Roger  (K8RI)


On 5/25/2013 1:07 PM, Joseph or Ruth Patrick wrote:
> 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

And Glock made the Seniors a lot more 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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