[TowerTalk] Drip irrigation tubing as conduit, revisited.
patrick_g at windstream.net
Sun Mar 23 09:55:59 EDT 2014
Previously I mentioned here that I wanted to use 3/4 inch ID black
plastic drip irrigation tubing rated for 100 PSI and available for about
$12 per 100 ft roll at the big box stores like Lowes or Home Depot for
conduit thinking it would be good for burial or environmental protection
above ground as it has good UV resistance. I got replies indicating it
had been tried and failed, especially in longer lengths.
I purchased 4 each 100 ft rolls of the 3/4 inch 100 PSI drip irrigation
tubing. I wanted to use it to protect 8 wires, 6 each #14 and 2 each
#12 that would run underground from a barn to a tower site just under
100 ft away. I rolled out one 100 ft section and clamped Vise Grip type
pliers to each end to facilitate keeping the tubing from rolling back
up. I then the ran my electrician's tape through the tubing, attached a
3 stand polypropylene rope (cheapy from Harbor Freight) and retracted
the tape pulling the rope through the tuning.
I set up a painters ladder with the backside toward the tubing but a few
feet away from the end of the tube. I placed a scrap of pipe through
two of the rolls of wire and suspended them by tying para cord from the
axle to the ladder's braces. Note, the ladder rungs are too close
together to allow free wheeling of the rolls, hence using the backside
where the braces are farther apart than the rungs. I similarly suspended
the other two rolls of wire. Four rolls of two conductor wire. Three
rolls are 14 ga and one roll of 12 ga.of wire. I wove the wire through
the rope a few (4 to 6) times. You do this by twisting the rope against
the lay and it opens up enough to put a wire through it. I then taped
the ends of the wire tightly to the rope.
I then manually pulled on the rope while holding the tube with my other
hand and the 8 conductors (4 pairs) of wire were easily pulled through
the 100 ft length of tubing, There was room for a few more conductors,
I think, before pulling would have become really difficult. I had a
quart of electricians wire pulling lubricant standing by but didn't need
it. I repeated this process for a total of three irrigation tubes full
of wires. My rotators require 8 wires each so this handles two rotators
and leaves 8 conductors for coax relay switching and winch control for
I have subsequently pulled the three tubes full of wires plus a 10-2
with ground direct burial romex through a buried conduit to the tower
located nearly 100 ft from the barn. I pulled all of this at the same
time in one shot. It was considerably more physically demanding so I
had the only other ham in my zip code mind the bundle as it went into
the conduit were it exited the barn while I pulled at the tower end. I
could manage it but it was strenuous so I tied the rope to the pickup
and slowly drove away. All went fine the second try. The first try the
rope pulled through nearly a roll of electrical tape. Manually removed
the bundle from the conduit, tied constricting knots around the bundle
(should have done this in the first place) which get tighter the harder
you pull. All went perfect on the second try. Neither the pickup nor
myself were physically challenged.
This drip irrigation tube in 3/4 inch ID at about $12 per 100 ft seems
like an excellent way to bury wires if you are not going to try to add
more conductors after the fact. I don't know, not having tried it but,
it might be difficult. With its UV resistance it is a good way to
weatherproof wires above ground as well, say on a tower for instance.
Once in place you could seal the openings with RTV or... Something of
interest I haven't tried yet is to "splice" lengths of tubing together.
I'm thinking a couple inches at the end of a roll could be heated and
expanded (belled) just a little to allow mating another section and with
an appropriate glue and maybe some RTV on top you should have a
Why did I use this tubing for wires in a conduit? Concern for
condensation or leaks and because it is cheap insurance, very good
insurance. Undoubtedly some of my description of how to will not be as
clear as I intended. Send me an email (I'm good on QRZ) and ask
anything. I will be happy to try to clarify.
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