[TowerTalk] Water in Conduit...

[Patrick Greenlee]

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 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
>
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