Jim, put on your flame retardant longhandles. I posted similarly and
took incoming fire for quite a while. Seems some folks refuse to
believe that PVC pipe that can hold over 100 PSI on the inside can't
stop a PSI or two from the outside toward the inside. I use 4 inch S&D
(cheaper, lighter, and strong enough) for several runs for power, coax,
control lines etc. I have one small section with a leak due to improper
back fill (by me) which I regret but fixed. I use the one inch ID low
pressure (good for 100 PSI) plastic irrigation tubing to sleeve the
lines just in the region of the aforementioned leak. Yes, a band aid,
but I was overcome by a gust of laziness and didn't want to dig it up,
replace it, and bury correctly.
My glue joints don't leak. I have string in the runs to pull a rope to
pull more cables. I can tie it such it is continuous, half inside the
conduit and half outside, Tie on a rag and pull it through a hundred
feet plus of pipe and it comes out dry. (not the run with the leak)
I was warned that I would get condensation but years later it hasn't
happened yet. If I got any I would put a small muffin fan to circulate
air when the humidistat said it was dry enough and let it shut down when
conditions were favorable to condensation. Alternatively I could slide
some bags of desiccant in on the pull string and check them periodically.
Those of you unable to keep water out of your conduit have my sympathy.
I know how irritating it could be. If your conduit is assembled properly
and doesn't leak leaving the airborne moisture as your target then put
desiccant bags in the conduit and plug the ends of the conduit where the
cables enter/exit. Various ways to plug include duct tape, spray foam,
wadded up paper coated with silicon caulk or...
Patrick NJ5G
On 3/5/2015 4:52 AM, Jim Thomson wrote:
Date: Wed, 4 Mar 2015 21:34:54 -0600
From: "Perry K4PWO" <k4pwo@comcast.net>
To: <towertalk@contesting.com>
Subject: [TowerTalk] Water in Conduit...
I still don't understand the "French drain" stuff. I have a 70' run of two
3", one 2.5", and two 11/4" conduits from my tower to my house. At each end,
I have the conduit terminated in metal 18" X 16" X6" NEMA 4 boxes. The
boxes allow the conduit to breath and in the seven years they have been
installed, all I've found in them is cob webs. I just pulled some Cat 5E in
one of the 11/4" runs and it was as dry as a bone.
Like a lot of the Southeast we are currently in the middle of a freezing
lake... flood, then ice, finishing with snow. In other words a lot of
moisture. If I had used the "French drain" my coax coax would be swimming.
Perry K4PWO
## The problem with using that pvc pipe that has the rows of holes on each
side is..
its meant for perimeter drains.... to allow water INTO the pipe. For ham use,
the
pipe would have to be flipped 90 degs..so the holes are at 12 and 6 oclock...to
allow
water out the bottom holes..into some gravel bed etc. Trbl is.... it will also
allow water
in through the top holes! You would be better off to buy pipe with no
holes..then drill
ur own holes..at 6 oclock only.
## On a similar note, the telcos, power and cable companies all use pvc pipe..
with no holes at all. Each end of the pipe is terminated correctly, and the
entire
length can breathe. Never saw one with water issues in it. Telcos used to
direct bury
a lot of stuff..in residential areas. That stopped a long time ago. Cable
goes bad,
and has to be replaced. That requires ripping up every driveway and boulevard
up and down the street. When the replacement cables started to go bad, and a
3rd
was required, city hall read em the riot act..... no more direct bury.
Everything
has to go into pvc pipe..and big diam stuff too.
## a lot of problems with ham installs is..too small a diam pipe is
used....and down the
road this will bite you. Flip side is.... trying to remove a cable, when
several are already
inside the same pipe is a real pita at times, with cable sheaths burning on
each other.
Cables should be lubed before install. How long the lube will last is
anybodys guess.
## Plan B would be to install several pipes at the same time... at least two.
With coax
in one..and control, misc and any power cables in a 2nd pipe. Use control
cables with plenty
of spare conductors. You might even want to run spare coax cableS as
well..at the same
time, then cap off the spares at each end. Its actually easier to run all the
intended cables
at one shot..all at the same time.. vs 1 cable at a time.
## if running cables laid on top of the ground, that split loom, corrugated
tubing,
installed over top of the cables will allow for a certain amount of protection.
Jim VE7RF
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