[TowerTalk] Condensation

[Roger (K8RI) on TT]

I use NEMA boxes with gasketed doors. Cables leaving the box now go 
through either bulkhead connectors, or plastic fittings with compression 
glands (I forget the name of them) The conduit into the basement goes 
into a similar, but much smaller box with the same size conduit out the 
back and through the end plate under the floor and into the basement. 
The basement end is left open.  The run from the tower goes through a 
sweep 90 and into another NEMA box.  The conduit stub through the wall 
is sealed with expandable foam.  I had been getting a surprisingly 
strong flow from the basement, through that sealed junction box and 
finally into the shop summer or winter. Even with that strong flow, 
condensation was never a problem.  Nor was it a problem.

 From that, I concluded in my installation that worry about condensation 
was not worth it, but as I said before, even were there water in the 
conduit I don't see a problem.  Direct burial coax has a gel fill 
between the jacket and internal insulation, but that is there to stop 
water migration from damage caused from stones, or other causes, none of 
which are present inside conduit.  A coax with a good jacket that stands 
up well in weather should have no problem with water in conduit. Gel 
filled coax is OK, but expensive overkill.

The  run into the basement  used to be 5" plastic sewer pipe in through 
the basement wall and open at both ends with a "Y" pointed down at the 
low end as a moisture trap and drain. The down stub was capped with tiny 
drain holes in the low spot in the cap.  When the contractor replacing 
the septic tank caught a ground cable and pulled out a bunch of blocks 
in the basement wall, I went to the present system where the underground 
conduit is about 3 feet below the ends and has a vertical run into the 
boxes on both ends.  Our "current" contractor then poured and dodder the 
entire basement wall as well as resealing the outside, adding 1" 
Styrofoam to the outside of those walls and installing new weep tile.

The basement wall work, old conduit,  "Y", and new conduit installation 
are shown in http://www.rogerhalstead.com/ham_files/cablebox.htm as well 
as the messenger cable in the box at the house.  The installation of the 
run to the shop as well as the NEMA box at the tower are also shown.

  73,

Roger  (K8RI)


On 2/1/2016 Monday 9:34 AM, Russ Dearmore via TowerTalk wrote:
> John,  You are correct in that few pipes are sealed by anything other than the junction box.  When sealing is called for a foam sealer is usually specified.  The only exception I can think of off-hand is in rigid pipe in explosive locations such as gas stations where a product called Chico is used.  Don't quote me on the name as it's been 30 years since I wired a gas station. Hi  I used the foam sealer in a highly methane location which was an amphitheater built over an old city dump in Mountain View Ca.  Maybe Canada has different code requirements but I seriously doubt it.  Besides, duct seal would make a poor pipe seal.  Russ      K5ZZR     My Heroes Wear Combat Boots!
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