Weatherproofing of Enclosures

[DWEames]

I'm an electrical contractor (almost licensed I hope) working in New Orleans, LA. We have lots of rain in case you didn't know. Today a customer called me about her ARC fault breaker tripping. I told her that the ARC fault breaker is prone to that. But I didn't have a lot of good answers about why. I told her they suck in water. But I was hoping to alleviate her concern on the issues of standard breakers as well as her meter, etc...This is a house with no eves, or gutter (which I've run into more times than you would imagine), and that leads to the question of the code, and how/when to properly install outdoor rated panels in situations with extreme water issues due to building types, and if and when water is a persistent problem, how to more adequately protect these panels from the intrusion of water...Any practical or scientific input much appreciated.

 

[Jraef]

I'm an electrical contractor (almost licensed I hope) working in New Orleans, LA. We have lots of rain in case you didn't know. Today a customer called me about her ARC fault breaker tripping. I told her that the ARC fault breaker is prone to that. But I didn't have a lot of good answers about why. I told her they suck in water. But I was hoping to alleviate her concern on the issues of standard breakers as well as her meter, etc...This is a house with no eves, or gutter (which I've run into more times than you would imagine), and that leads to the question of the code, and how/when to properly install outdoor rated panels in situations with extreme water issues due to building types, and if and when water is a persistent problem, how to more adequately protect these panels from the intrusion of water...Any practical or scientific input much appreciated.

Contrary to popular belief, a Type 3R "Rain Tight" enclosure does not exclude water from getting inside, it only excludes water from getting to any LIVE ELECTRICAL PARTS inside. Should not matter if the house has eaves or gutters, a proper Type 3R enclosure in good condition is supposed to stand up to wind blown rain, sleet and snow. If the enclosure is compromised somehow, or conduit connectors were not done properly, that's another matter and something you could easily correct for her.

As to the AFCIs tripping, can't help you there.

 

[J.P.]

Build a overhang or enclosure for the panel.

I have seen panels with water running through them that weren't tripping breakers though. Water in a panel doesn't mean instantly shorting out like in the movies. It means corrosion in a while and then the shorting and arcing may occur.

As far as the arc fault.........There are many possibilities there. They can be pretty touchy. Vacuum cleaners, lights, lots of normal things can give you fits with arc faults. I can't say as I like them all that much.

Go have a look.

 

[kwired]

As far as water entering the enclosure - if you have raceways entering the top wall you will get condensation forming in those raceways, possibly almost on a daily basis, and it will run down and into the panel. You should try to make top entries near the side walls and then form drip loops in your conductors before landing on breakers so any water that follows the conductor after entering via the raceway drips off the bottom of the loop instead of following the conductor all the way to the breaker termination where it will just promote corrosion of the termination or even find a way inside and cause problems there. High humidity areas are going to have condensation problems in raceways, and one needs to take that into consideration when designing things.