Condensation Revisited

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Old 01-01-14, 10:49 AM
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Condensation Revisited

I have read threads from several years earlier that adequately discuss the issue of condensation but do have a couple of lingering questions.

The Situation
I recently added a gas heater to my garage and not long after the breaker for the lights (ceiling boxes) and the ceiling outlets began tripping. I found the offending ceiling box, one where the conduit extends upwards 12" inches into ceiling-insulated freezing attic space before bending 90 on its way to another box.

To confirm it, my wife turned on the breaker and a pop ensued along with a spark that floated gently to my garage floor. Yeah.

Condensation is forming inside and outside the conduit, and I suspect there's a crack in one of the wire's insulation causing a short. (There is an ingress and egress conduit, with a couple wires (black) just passing through on a tight bend.) There is actually enough moisture where I can see ice on the side of the joist even though it's insulated. It's been a moist winter so far...

Questions
1. After I find and replace the problem wire, will using duct seal prevent (or greatly inhibit) the collection of water inside the conduit?

2. Since condensation is forming on the outside of the conduit, too, need I be concerned with this if my connections in the box are properly made?

3. Hopefully the bad wire isn't one that's just passing through. Rewiring that seems like it would be a real pain.
 
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Old 01-01-14, 12:17 PM
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Welcome to the forums!

1) Yes and no. Duct will prevent air from moving through the pipe which will reduce condensation. It will not eliminate it.

2) No. Properly made connections should have no issues unless the box fills with water, which I doubt. Water will have no effect on THWN wire.

3) If it is conduit, and the conduit was properly bent, there should be no problem pulling out the old wire and installing new.
 
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Old 01-01-14, 01:01 PM
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If your gas heater is not vented to the outside you are introducing a lot of water to the inside of that garage. The condensation you are dealing with may just be the first of many problems.

Bud
 
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Old 01-01-14, 02:17 PM
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It's a vent-free wall-mounted type and, yep, it does cause a lot of moisture. Addressing that is for another day, and another forum, I suppose.

I found the offending wire of the five in the conduit, the black/hot one, about an inch up. And it is one passing through to the next box. It has about 2 inches of bad corrosion, or perhaps just damage from way too much arcing over time. Tied a fish string to the other end and pulled that puppy out to replace.

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The others look ok, best as I can tell.

Thanks for the answers, TI.
 
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Old 01-01-14, 02:33 PM
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Glad you found it! Looks like it was skinned when it was installed.
 
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