Mystery moisture in electrical panel does not evaporate

Thread Starter

strantor

Joined Oct 3, 2010
6,782
I acquired a Rittal control panel which came from decommissioned machinery last year and it had some servo drives, contactors, breakers, power supplies, and relays inside. Before I loaded it up I wrapped it in several layers of heavy duty shrink wrap. On the trip home it got rained on.

Upon arrival I removed The shrink wrap and found that some moisture droplets (I assumed from the rain) had made their way inside but the panel was in great shape and the drives appeared in great shape too. I did not power up or test anything. I just gutted the panel and put the drives on a shelf, wiped out the moisture from the panel, let it air dry for a couple days, and then closed it up and moved it to the back of my shop where it became a horizontal surface for junk to collect.

Fast forward to now, I found a use for the panel, I open it up, and the inside of just one door... Not the other door, not the back subpanel, not the ceiling, nor the sides, nothing except the inside of that one door, is covered in moisture droplets. All the galvanized door latch mechanisms for that door are heavily corroded, while the rest of the panel is still in great shape. It's a NEMA12 panel, so at birth it was airtight, but they had installed vents and the floor of the panel was missing, so there was means for the panel to exchange air to the outside.

I don't think I missed wiping away any moisture before storing it, and even if I had, I don't see how it would have remained for a year without evaporating. I left the panel open in my shop for two days and the moisture did not evaporate. It remained collected in lines, outlining where I had wiped with a rag 1 year ago. Since it did not evaporate, I wiped it again, removed the latching hardware and wire brushed the corrosion off, sprayed with clear coat. The problem seems to be mitigated now but I can't help remaining curious what that moisture was.

It was not oily. It felt like water to the touch. Had no odor. Did not burn the skin. I think any reasonable person would conclude it was water, but it refused to evaporate, and only collected on that one surface. Any ideas? Might this be electrolytic capacitor blood? Maybe one of those drives had a bad day before I picked it up?
 

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MaxHeadRoom

Joined Jul 18, 2013
28,619
Try a bag of Dry-It (Silica-Gel) from H.D. etc, place a pan below it in order to catch any moisture that the bag collects.
Max.
 
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Alec_t

Joined Sep 17, 2013
14,280
Could the drops have been condensation? Any idea of the temperature of the door at the time? Is the material of the door exactly the same as that of its mate?
 
Dew point

Your going to get condensation when the surface temperature is less than the dew point. You can find the dew point with the relative humidity and air temp or wet and dry bulb temperature.

Something can be absorbing the water too.

Methanol or even Isoproprol (sp?) can displace water. Wiping what you can with that can help.

Desiccant (Silica Gel) is always good too.
 

Reloadron

Joined Jan 15, 2015
7,501
I use silica desiccant packets in my gun safe to absorb moisture in my gun safe and check the relative humidity on a regular basis. Not that you need anything like that just for a cabinet enclosure. When the temperature drops below the dew point of the air inside the cabinet condensate will form. That does not mean what you have is water even though it seems odorless and feels like water. I sure as heck wouldn't taste it. I would wipe it down, as suggested, with some good isopropanol alcohol and leave it open exposed to air. The merit to silica desiccant is when my bags stop working I just bake them out in the oven but it doesn't seem like you need a long term ongoing solution. I would wipe it down, maybe use a hair blow drier and see what develops after cleaning it up.

Ron
 

BobaMosfet

Joined Jul 1, 2009
2,110
I use silica desiccant packets in my gun safe to absorb moisture in my gun safe and check the relative humidity on a regular basis. Not that you need anything like that just for a cabinet enclosure. When the temperature drops below the dew point of the air inside the cabinet condensate will form. That does not mean what you have is water even though it seems odorless and feels like water. I sure as heck wouldn't taste it. I would wipe it down, as suggested, with some good isopropanol alcohol and leave it open exposed to air. The merit to silica desiccant is when my bags stop working I just bake them out in the oven but it doesn't seem like you need a long term ongoing solution. I would wipe it down, maybe use a hair blow drier and see what develops after cleaning it up.

Ron
BINGO. Every time I get a shipment that has any larger dessiccant packets, I keep them for this purpose. I have a couple I keep in my vehicle, and I put them anywhere I don't want moisture build up.
 

Thread Starter

strantor

Joined Oct 3, 2010
6,782
I've already cleaned it with alcohol (after cleaning it with WD40, then degreaser) and I have a stock of dessicant bags that I put in all the panels I build. I will give this panel the same dessicant prescription I always give, once I build it out for its new purpose.

I was more looking for ideas on what the mystery moisture might be (since it doesn't seem to behave like normal condensation or leftover rainwater), and if it might spell problems down the road in its new home.

Heck, maybe it was just condensation. Maybe the inside of that one door was cleaned with some kind of solvent that made it more condensation-friendly. But the conspiracy theorist in me suspects it's not that simple. I mean, I gave it two whole days with the doors open to evaporate and it never did. And I have lots of other enclosures and other sealed/ unsealed containers in my shop and nothing has ever had condensation like that.
 
You may have had some silicone or wax on the rag that you wiped it off the first time. The waxy surface will make bigger drops of condensation that tend to hang in place (like after you wax your car). The big drops don't dry as fast as the little droplets and the big ones dry much, much slower than when water just sheets off because there is no wax at all.
 

atferrari

Joined Jan 6, 2004
4,764
When loading soda ash (Port Arthur TX) dust crep into the control panels of our derricks. We learnt about the disaster, 18 days later, alongside in Bs. Aires when starting the discharge. :( The massive short circuits in all of them was an awful surprise.

Bonus track: most of the paint of the accomodation's structure was peeled off by then.
 
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