I agree with Jim and I'll add this again with a bit more detail:
I use 3" PVC conduit with NO drain holes and NO glue. Sll joints are
greased with either DC4 or DC5 compound (Silicone Grease) with the pipe
installed with linear compression. During much of the year, the
basement is much warmer than outside, providing substantial convection
air flow. The flow first enters a steel NEMA box on the outside wall.
The Conduit leaving the box extends "up into the box about an inch."
Most condensation takes place in that box. Any liquid in the box is
trapped.
In the warmer months the flow is reversed with the temperature in the
conduit and basement being much cooler than the outside temp. In spring
and fall which are often quite humid there can be substantial air flow
with the associated condensation. The air flow can easily be enough to
blow out a lit match. However, the flow often reverses between day and
night with the nightly outflow "usually" drying out the day's accumulation.
OTOH, as Jim said, even if the conduit is full of water there are those
infamous words, "what difference does it make?" IOW, The big boys
(commercial ops) pull through conduit full of water with little or no
problem.
Pulling "LUBRICATED cable in or out of conduit makes a huge
difference!" Look at the last photo on
http://www.rogerhalstead.com/ham_files/cablebox.htm to see a liberal
application of wire pulling soap. It make pulling the "BUNDLE" in much
easier and pulling only a single cable out much, much easier as the
cables do not grip others in the bundle. It's like working with a
bundle of cables covered with snot!
BTW that page also shows much of the evolution my feed system has gone
through.
Get some help. One guy pulling with two lubing ( one holding and
spreading the bundle while applying the wire pulling soap. The second
squirting the soap into the first's hands) and another feeding the
cables into the "soaper's" hands. With little practice the cable
pulling operation is quick and easy. So is pulling a wire or two out.
Do this with all wire bundles going through conduit, even AC wires
through EMT indoors.
73
Roger (K8RI)
On 3/5/2015 5:52 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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73
Roger (K8RI)
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