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Sweaty conduit pipes after foam insulation board was added

Sweaty conduit pipes after foam insulation board was added

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  #1  
Old 08-15-17, 06:57 PM
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Sweaty conduit pipes after foam insulation board was added

I recently put 2" foam insulation boards on my cinder block basement walls. It's a walk out basement so these walls are actually on the above ground side. There was already existing electrical conduit and I carved out trenches in the foam board and covered the conduit. I was putting up the sheet rock screwing it to the furring strips and noticed that there was moisture coming from the area where the conduit was located, so I removed parts of the foam and noticed that the one of the pipes was sweaty and dripping. I'm pretty certain that it's not a leak. My question is should I insulate between the pipe and the cinder block or should I wait until my walls are finished and just put outlet insulators under the covers to keep the warm air out of the electrical? Or should I do something entirely different? Any advice would be appreciated.
 
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Old 08-15-17, 09:12 PM
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Post moved to Electrical Forum.
 
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Old 08-15-17, 10:09 PM
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Would be helpful to understand what the pipe is!
 
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Old 08-16-17, 01:52 AM
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Would be helpful to understand what the pipe is
Marq the O/P wrote:
There was already existing electrical conduit and I carved out trenches...
So assumed he had correctly identified it. That it really was conduit so I moved it here.
 
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Old 08-16-17, 04:15 AM
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The most obvious cause is air traveling through the interior of the conduit. Using Ductseal (available in the electrical aisle of most big box mega-mart homecenters) try pushing a small glob into the open conduit, sealing around the wires. Best to turn off the power first.
 
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Old 08-16-17, 05:19 AM
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Moisture is getting in.
2. Through the concrete foundation wall from the outside. (Concrete is not non-porous.)
3. From the interior basement air that permeates the space where the conduit runs because that space is not hermetically sealed from the interior. (If it were then #2 would be exacerbated.)

You said that at least one pipe is very sweaty and at least one pipe is dry. The one that is sweating must be a cold water pipe that undergoes frequent temperature changes namely cooled down by new water flowing through it and warmed up by the surrounding air and objects after the water has stopped flowing.
 
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Old 08-16-17, 08:20 AM
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JM are you certain they are conduit? If so where do they come from and where do they go.
 
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Old 08-17-17, 05:59 AM
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Yes it is electrical conduit. It connects 2 - 4" x 4" outlet boxes, which I have put extenders on so the cover plate will be flush with the drywall surface. I will also put insulation under the plates to keep the warm air out of the conduit.

There is a 1/2" gap between the conduit and the cinder block wall. On this particular stretch I insulated over the pipe and not between the pipe and the wall. I'm thinking that I should've insulated between the two and that this will make a difference by keeping the pipe warmer. Any thoughts on that?

I don't think there is moisture in the pipe as I didn't see any inside the boxes.
 
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Old 08-17-17, 09:31 AM
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One end is in the 4x4 boxes in your soon-to-be-finished basement. Where's the other end of the conduit? Like Furd said, I think it probably terminates in a garage or some non-conditioned space, so the outside air is passing through the conduit, creating a temperature differential between the inside and outside of the conduit, creating condensation.

Seal one or both ends of the conduit with ductseal, and I'm pretty sure the moisture issue will be resolved!
 
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Old 08-18-17, 07:22 PM
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Thanks for your reply Zorfdt.

No the pipe never leaves the room. The only thing that does is a cable bundle wrapped in a black plastic/rubber that goes into the room's electrical box with 4 breakers. I did notice moisture on the cable but it also came in contact with the pipe that was wet. The bundle goes up into the joist and goes to the main box. Could that be the culprit?
 
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Old 08-26-17, 11:18 AM
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I let the pipes dry and I put a foam insulation strip between the electrical conduit pipe and the cinder block and then put the piece of foam insulation that I had carve out for the pipe to fit underneath back over the pipe. I let it sit for a few days and I checked it and it was still wet but much less.
 
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