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Re: [TowerTalk] TowerTalk Digest, Vol 122, Issue 58

To: towertalk@contesting.com
Subject: Re: [TowerTalk] TowerTalk Digest, Vol 122, Issue 58
From: K8RI <K8RI-on-TowerTalk@tm.net>
Date: Thu, 28 Feb 2013 12:55:52 -0500
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
On 2/28/2013 10:38 AM, Patrick Greenlee wrote:
Lots of opinions and no consensus.  Typical.

I didn't have nary a drop of water in my 3 inch conduit 6 months ago but
I will check again because of all the folks who think all buried
conduits have water.

It's not that all buried conduit will have water, it's just most any buried conduit is likely to get water at times.

Presently mine which is shallow enough to be in frozen earth and open on both ends with none of the joints glues doesn't have ant water standing in it, T%here are NEMA BOXES on each end, There is about a 6" stub through the end plate into the basement. As on end is into the fairly warm basement, this is a prime location for condensation and frozen droplets. There is none at present and pulling out 4 or 5 feet of pull line shoes no moisture. Due to the heating system in the house this tends to have a negative pressure causing a slight flow into the basement.

The pull rope will show moisture in the spring when the relative humidity is high, but "so far I've never found liquid water.

Very cold air enters through the fittings in the large box at the base of the tower.. even in the frozen ground it is warmed a little above the outside air temp. which reduces the relative humidity. In the spring warm, humid air enters at the tower and is cooled which raises the relative humidity which will cause condensation. As the ground warms with the onset of warm weather this condensation will evaporate. The typical time for there to be condensation in the conduit is 4 to 6 weeks although there a few times in late spring, early Summer, or fall when conditions may be right for a few days.

It'd be interesting as to how much cross flow there is between the basement and shop as the conduits have the box at the base of the tower in common.


A dry air purge through the conduit dry but is it worth the effort?
http://www.rogerhalstead.com/ham_files/cablebox.htm shows the history and what I have from the basement to the tower as well as from the shop to the tower.

Originally I had a 5" sewer pipe from the tower to the basement with a "Y" just before entering the basement. One leg of the "Y" was down and capped. The cap had some small holes for drainage if necessary. Almost the entire run is in the sand back fill around the basement. There is a weep tile at the bottom so the sand is always dru excep when it's raining and then the water just drains down through the sand.

The run from the shop to the tower is basically below the watwe table in the spring, but it's open on each end. I've not had problems with water in it, but I don't think it'd be a problem were it to be filled with water.

I can see where water can be a big problem with direct burial coax, but not with coax in conduit unless it's there when you wish to pull cables in or out.

73

Roger  (K8RI)


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