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MoreCowbell77 02-17-2012 10:43 AM

Soaked my 200A panel
I bought a new (2008) home recently and noticed a small amount of liquid on the ground in the basement under my 200A main panel and subpanel.

Upon investigation I found a couple 2" PVC vent pipes in the basement ceiling directly above the panel. It turns out they were put in for a future basement bathroom (already roughed in) and were capped w/test caps. I felt the pipe to see if that was the source of water and the test cap, which was apparently already holding on by a thread, let go like a cannon the moment I touched it, dousing me and everything around me, including both panels, with a few seconds of rushing water. Those were a very long few seconds for me. I immediately turned the main breaker off, took the cover off, soaked up as much water as I could (and, btw, almost touched the service wires coming into the 200A breaker before I realized they were still hot. Would I have died if I touched the service wire while soaking wet and standing in a pool of water? Maybe I don't want to know).

I ran a cord from a neighbor and set up fans and forced warm hair dryer air for about 8 hours. When I was reasonably sure it was bone dry I turned the main breaker on and each regular breaker individually until power was fully restored.

The main panel has no signs of rust - I'm fairly certain it only saw the one major 'water event' that happened when that cap blew.

The subpanel has a very small amount of rust at the very bottom of the enclosure. It's directly below where I found that leaking vent pipe & test cap so I'm thinking it saw moisture for some time, well before it blew. It too, is completely dry now (I gave it an additional day of fan/heater attention) and seems to be completely functional.

My question is - how easy should I be sleeping? The main panel has 40 breakers and is at capacity, sub has about 12 and is half full. Replacing all the breakers would be a huge expense; wondering if doing so would be going overboard if everything was thoroughly dried, or am I putting myself at risk for not doing so.

Thanks for any opinions/advice.

Yoyizit 02-17-2012 11:08 AM

Rust should eventually compromise mechanical strength.
How important is mechanical strength for a panel and how much reserve mechanical strength does a panel have?
This is not like a car door hinge.

I guess you could use a Megger to check for trapped water.

rrolleston 02-17-2012 11:14 AM

Were the panel doors open?

MoreCowbell77 02-17-2012 11:23 AM

1 Attachment(s)
Doors were closed but when I took the faceplate off the panels everything was dripping wet as there are holes at the top of the panels for wiring to come in.

I attached a picture, not sure how clear it is - this is minutes after the torrential downfall, before I sopped everything up with rags (probably stupid even w/breakers off) and then started w/fans and hair dryer.

I'm a total newbie so not sure what a Megger is.

Thank you.

Yoyizit 02-17-2012 11:25 AM

MoreCowbell77 02-17-2012 11:26 AM

I should specify - I don't know what to do w/said megger. How would I test for trapped water?

rditz 02-17-2012 11:47 AM


if this just happened recently, you will not see any rust for sometime, if at all. You say you got it cleaned up in short order, so the likelihood for rust is minimal.

secondly, if everything is dry, then you have nothing to worry about. you say that all circuits were powered back up, and you make no mention of any that have stopped working.

you have no reason not to sleep well.

now, i would suggest that you either find out why you are getting water in the PVC pipes abour your panels or you cut them back or re-route them.. either way, you don't want this to happen again.

good luck


rrolleston 02-17-2012 11:50 AM

Even if everything looks dry. Having a box fan blowing air into the panel for a while would not hurt either to help make sure any water hiding is dried up.

MoreCowbell77 02-17-2012 12:14 PM

Thanks, that's what I was hoping to hear.

I do have a couple fans blowing directly onto the panels 24/7 and will keep it like that for at least a few days. Looking for a deal on a dehumidifier as well - should have had one down there anyways, could really use one now to work at drying out the insulation around the area that got soaked.

My project this evening will be to reroute and more thoroughly cap those vent pipes. Want to strangle whatever plumber decided to put in a pressure-fitted cap onto a pipe that slowly fills with water over time and is located directly above our electrical panel!

Thanks again.

Edit to add - those pipes go straight up to the roof for plumbing ventilation. There's no cap or anything on the roof, they go straight up. I asked a plumber friend if I could put a 'U' on the end to prevent rainwater buildup over the years and he advised against it as he thought it might hinder proper ventilation.

joed 02-17-2012 12:17 PM

Did you fix the clogged drain that probably caused the water backup into the vent line?

MoreCowbell77 02-17-2012 12:22 PM


Originally Posted by joed (Post 855824)
Did you fix the clogged drain that probably caused the water backup into the vent line?

That's a good point, I don't know for sure where that water came from. I called the original contractor on the off chance he would help me and he was kind enough to tell me he believed it was rainwater coming in from the top of the pipe at the roof. I suppose I was running under the assumption he was correct ... I'm not very familiar w/how bathroom venting works, and whether he is right or it's another issue? We have no clogged drains - on occasion a toilet will get a little backed up for no apparent reason and I'll plunge it. I assume it was the standard-issue builder grade toilets and was planning on replacing them at some point.

rrolleston 02-17-2012 12:33 PM

I would cut them back as far as you can away from the panel and add a fitting that allows a threaded plug.

Yoyizit 02-17-2012 01:28 PM


Originally Posted by MoreCowbell77 (Post 855780)
I should specify - I don't know what to do w/said megger. How would I test for trapped water?

With the breaker off with trapped water your Megger should read low values of resistance, like in the megohm range. A regular DVM on the ohms range might also detect water bridging internal contacts.

Loading down each breaker to near its max should accelerate the drying process. You could measure the resistance before and after.

joed 02-17-2012 01:35 PM

Vent piping should be sloped and connected to the drain line it is venting. Any water in the vent line should drain down the drain. If it is not draining then it is clogged or sloped backwards.

rditz 02-17-2012 01:41 PM


Originally Posted by joed (Post 855863)
Vent piping should be sloped and connected to the drain line it is venting. Any water in the vent line should drain down the drain. If it is not draining then it is clogged or sloped backwards.

OP said that it wasn't connected to anything, it was a roughed in pipe for future bathroom downstairs. it was capped... when he touched the cap, it blew off allowing the accumulated water inside to spill on to the panel.

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