[TowerTalk] IN SEARCH OF PVC Tubing to Bury...

[yetiguy at earthlink.net]

Wow! Neat project.

   The sheer 1500-foot length of the conduit run implies a lot of drag on the "fish line", and then on the fibre optic when you pull it through. What if this fish line breaks?  I strongly urge you to use PVC conduit larger than you think you need.  And, pull-in a parallel fish line with the fibre optic, and leave it in there.  Make the connection between the fish line and the fibre optic/second fish line a smooth connection. Streamline the connection with a little plastic electrical tape so it can't hang up on a conduit joint, but will slide over it instead.

    PVC conduit cement can form hard drips blobs inside the conduit if you use too much when making up a joint.  These can snag the fish line.  I recommend using just a little PVC "blue primer" on both the female and male ends of each joint, BUT PUT THE PVC CEMENT ONLY ON THE MALE END (except the last 1/4" at the end) - a very thin layer at that - and plunge the male end home as you twist it a quarter turn: hold it there for about 20 seconds while the cement sets. Practice this on a few joints before you tackle the real thing. Practice is cheap.

   If the fish line breaks while pulling in the fibre optic you will wish you had installed a couple of above-ground (or below grade) "pull boxes" to break the run into more manageable, shorter lengths.  Consider pulling (vacuuming) the fish line through the conduit BEFORE you back fill the trench - just in case of a break. 

    On long runs you could also blow compressed air at the source end, while vacuuming the destination end. Admit the compressed air with a PVC reducing tee, say 1" x 1/2" x 1" if you are using 1" conduit. Glue one 1" port of the tee to the start of the conduit run (it will be cut off later and discarded). Drill a small hole in a 1" PVC pipe cap to feed in the fish line without losing too much air. Start the foam mouse and fish line into the 1" conduit, then glue the PVC cap onto the remaining 1" port of the tee. Blow the air into the 1/2" port - propelling the mouse - while pulling a vacuum on the far end. The larger conduit helps here as well. The mouse should "just fit" the inside of the conduit.

   It's tempting to consider feeding the fish line through the conduit - 10 feet at a time - while you are laying and gluing 10-foot lengths of conduit. As long as you use minimal PVC cement you may be able to do this.  I've been successful on runs as long as 100 feet, but sooner or later I've unintentionally glued the fish line to the PVC. 

    BTW: "fish line" is not bass fishing leader or any cheap string or even light rope. The term means a line strong enough for this job.   Greenley makes a fibreglass "fish tape" on large spools, perfect for this job, I'd think. It's marked at 1-foot intervals as well (nice feature).  I have no interest in Greenley.  

Best of luck,    
Dennis, K6IFB
Placitas, NM

 



-----Original Message-----
>From: WA3GIN <wa3gin at comcast.net>
>Sent: Mar 4, 2010 6:15 PM
>To: TOWERTALK at contesting.com
>Subject: [TowerTalk] IN SEARCH OF PVC Tubing to Bury...
>
>...fiber line from house to ham shack/antenna controller.
>
>Source suggestions welcome,
>dave
>wa3gin
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