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I've heard that you shouldn't caulk the outside perimeter of the meter base or an outdoor electrical panel (sealing it to the house siding), because the panel needs to "breath" on the back. I haven't been able to find any specific code reference for this though. Is this code or hearsay?

  • It depends on how the panel is mounted but I usually run a bead across the top and then based on conditions down the side. If the panel penetrates the sideing I will drill a 1/4" hole close to the front bottom lip prior to power up and calk all 4 sides. – Ed Beal Oct 31 '17 at 20:10
  • Not a fan of caulking the bottom. Gravity does a pretty good job of keeping water from entering that way. When I have pole service, I attach it to a stout piece of plywood and then build a little birdhouse over it, with a door that opens of course, and bottom open because that's how cords come in. – Harper Oct 31 '17 at 20:57
  • If the bottom is not caulked, is there anything to keep critters out? Panels are warm and inviting hiding places... – Nick Nov 1 '17 at 13:36
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Do you have siding installed behind the electrical panel? If there is siding behind the panel, then do not caulk it to the siding.

If there is no siding behind the panel, then you can caulk the outside perimeter of the panel. If you have vinyl or steel siding, then you should trim it with J-channel and caulk the J-channel to the electrical panel. If you have any other kind of siding, then you caulk the top and sides but usually not the bottom of the panel to make sure you don't trap any water behind it.

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Do not caulk the meter main panel to your siding. I don't know of any code that addresses caulking around it specifically, but this of it like this: If you caulk all around it you've sealed the panel to the siding. The caulking could fail on the top edge. Rain drips down your siding in behind the panel. Where will that rain go? Either into your siding into your wall, or flood into the meter enclosure and short out or damage the meter. The panels keep rain out but are not submersible because there are knockouts and screw holes on the back of it. If you seal all around it, and some caulking fails or water seeps though siding, then you have created a wall of water behind your caulking, the siding, and the enclosure.

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    Yeah, a NEMA 3R should be flashed to the drainage plane behind the cladding, not to the cladding. That way, there is no possible way for bulk water to penetrate behind the box... – ThreePhaseEel Oct 31 '17 at 22:24

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