[TowerTalk] Water in Conduit...

[Roger (K8RI) on TT]

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 at comcast.net>
> To: <towertalk at 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
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk


-- 

73

Roger (K8RI)


---
This email has been checked for viruses by Avast antivirus software.
http://www.avast.com