[Top] [All Lists]

Re: [TowerTalk] Sealing cables at PVC exit?

To: <>
Subject: Re: [TowerTalk] Sealing cables at PVC exit?
From: "K8RI on Tower talk" <>
Date: Sat, 15 Jul 2006 13:58:19 -0400
List-post: <>

> Paul:
>     From your description I'm not sure exactly how your PVC is configured 
> at each end.  Assuming your PVC emerges from the ground vertically, you 
> ought to include a PVC U-turn (two 90-degree elbows) in the end(s) so that 
> the cables emerge DOWNWARD.  You can then use attic insulation to stuff 
> the end(s) of the PVC U's around the cables.  And don't glue these U's to 
> the vertical PVC; let them loose so you can remove them for easier cable 
> pulling.

I agree the conduit opening should be pointed *down*.

I use "sweep" 90s, or "sweep" 45s but I do have cable pulling boxes at each 
end.  One important thing with conduit; make certain all permanent joints 
are fully seated. If not it leaves 1/4" to 3/8" sharp shoulders inside which 
may make pushing a snake or cable through difficult.

With 3 or 4" conduit, use *lots* of "wire pulling" soap. It's messy but well 
worth the mess.  I ended up getting caught short on that stuff so I used 
plain old *mild* dish washing soap undiluted.  With a little electrical tape 
on the end cable so it's not squared off plus a bit of soap, I can "push" a 
run of LMR-400, or even RG-6 all the way through the roughtly 80 feet of 
conduit and that includes two sweep 90s and a pair of sweep 45s used to make 
a long 90.

>     This method: allows for the conduit to breathe, i.e., lets moisture 
> evaporate to a certain extent; prevents large fauna such as mice from 
> entering said conduit; and is easy to remove to add/remove cables in the 
> future.
>     In my conduit system the ends of the 3 inch PVC's enter steel boxes at 
> the shack and tower ends.  Therefore, I don't need to include such drip 
> loops in my PVC system.  At the shack end the cables are routed from the 
> steel box into the crawl space underneath the ground-floor shack.  In this 
> manner the moisture from the conduit can be evacuated from the crawl space 
> through normal ventillation.

Conduit does need to be able to breathe, but it also needs a way to drain 

Witht he soaft foam I use it can breathe, but I still need a couple of very 
small holes in the bottom of the conduit at the low point.

I did include a link showing the conduit run from the tower tohouse, but I 
did it a bit different in my shop.    The bottom 4 photos 
on the page show the coax routing into the shop as well as the 1 1/2" steel 
conduit run through the shop to the antique as well as the portable station.

The Cat5e network cable comes in through the south wall just to the left of 
the desk supporting the radio station.

BTW we have a devil of a time with paper wasps building nests in just about 
every available nook and crany.  I noticed I had to swat a bunch of them 
when I went out to my wife's old car.  Then I discovered they had build 
nests at the front and rear of the driver's door (In that space between the 
door and frame). No wonder I was so busy.  I purchase and use the Wasp and 
Hornet killer by the case.  They managed to get under the siding on the 
south end of the house up near the peak of the roof.  They built a nest so 
large they popped the siding off.

So far I've found the fiberglass insulation has to be stuffed in really 
tight to keep them out and the soft foam is the easiest way of keeping them 
out of the conduit.  Make a chunk of the stuff and let it harden. It's quite 
porous.  Give it a couple of shots of insect spray. I have a chunk of the 
stuff in each box at the end of the house to tower run. Since doing that I 
have not found a singel bee in there.

Currently the stub coming down from the box on the tower is open as I'm 
doing a lot of tower work at present...excpet for today.  It's way too *HOT* 
out there.  It's supposed to get hot tomorrow.

Roger Halstead (K8RI and ARRL 40 year Life Member)
N833R - World's oldest Debonair CD-2

> 73 de
> Gene Smar  AD3F
> -------------- Original message ----------------------
> From: "Paul Ferguson" <>
>> I am using buried 4-inch PVC pipe to run coax and control cables from
>> shack to tower base. The PVC come out of the ground, turn horizontal,
>> and end a foot or two above the tower base. The cables will exit the
>> PVC, take a small drip loop, and get routed onward.
>> What is the best way to seal the end of the PVC around the cables? I
>> thought about using a PVC end cap and drilling holes, but adding a
>> future cable would be difficult. I am interested in hearing what
>> creative solutions others have found.
>> 73,
>> Paul
>> K5ESW
>> _______________________________________________
>> _______________________________________________
>> TowerTalk mailing list
> _______________________________________________
> _______________________________________________
> TowerTalk mailing list


TowerTalk mailing list

<Prev in Thread] Current Thread [Next in Thread>