Condensation will form when surface temperatures are below the dew point of
the air inside your box. Ground moisture will migrate into your conduits
and thus into your box on warm days and elevate the dew point. Then when
it cools down it condenses. Suggest you try venting your box as N3AE
suggested. In outdoor commercial and industrial control panels we
sometimes mount heating elements to control condensation. I have also seen
light bulbs used but less reliable.
Good luck.
73
Matt
KM5VI
-----Original Message-----
From: TowerTalk <towertalk-bounces@contesting.com> On Behalf Of Shawn Donley
Sent: Sunday, November 12, 2023 12:48 PM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Condensation Inside Tower Cable Box
Thought I'd re-post with the solution to the problem described below. I
mounted a small (~ 2") 12vdc muffin fan on the underside of the box using an
enlarged hole that was for an extra cable. The fan blows outside air into
the box. The air must escape via space between the cables and grommets, but
likely more via the PVC conduit for my underground cables. Seems to have
completely eliminated the condensation problem so far. Completely dry
inside now.
N3AE
> Date: Mon, 16 Oct 2023 14:56:37 -0400 (EDT)
> From: Shawn Donley <n3ae@comcast.net>
> To: "towertalk@contesting.com" <towertalk@contesting.com>
> Subject: [TowerTalk] Condensation Inside Tower Cable Box
> Message-ID: <159386131.427573.1697482597363@connect.xfinity.com>
> Content-Type: text/plain; charset=UTF-8
>
> Hello fellow TowerTalkers,
>
> I have an aluminum outdoor electrical enclosure at the base of my tower.
My underground runs of hardline enter the box through a PVC conduit elbow
entering at the bottom of the enclosure. The tower coax and rotor cables
exit the bottom as well. In humid weather, especially this time of year
when the temperature goes down at night, I get a significant amount of
condensation inside the enclosure, not only on the enclosure but on the
outside of the cables within it. Enough water to make one think there's no
environmental protection provided by the enclosure in the first place. I
suspect the moist air from the conduit is the source since the underground
run uses slotted corrugated drain pipe covered with a soil sock rather than
solid wall PVC. Why ... concerns of long term condensation inside solid
conduit...another subject thoroughly discussed elsewhere and hopefully not
again on this thread.
>
> Has anyone experienced something similar and has a proven fix? I
considered a small 12v box fan to circulate some outside air through the
enclosure but I think the cold box walls would just condense that moist air
as well. Perhaps a low wattage 12v light bulb inside the enclosure to
provide some heat to keep the walls warmer? Some water pipe heat tape on
the outside of the box (but I would like to avoid any 125vac solution)?
Sealing the entry conduit is problematic with the several cables of
different diameters. I would not want to "foam" the conduit with expanding
foam or something like that which would make pulling a new cable much more
difficult.
>
> tnx
> N3AE
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