Exterior electrical panel, stucco, and air and water sealing
Hello,
Have a new build that we are trying to achieve good air and water sealing. Zip R9, taped seams, hvac penetrations have Quickflash or similar, receptacle boxes are Quickflash with zip tape taping the box to the zip sheathing. Stucco has an air gap layer, ventilated in the soffit.
My question is how to air seal and water seal exterior electrical panels. Our electrician said with stucco they typically put the panel on after the stucco, but I can’t see how we would seal the penetrations except spray foam.
I was thinking we could add a couple wider plastic trim boards under where the panel would go, stucco around that, and then wait until the electrician is installing the panel to air/water seal individual penetrations. Is there a better way to do this?
Thank you!
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Replies
Yeah, there is a much better way to do this: install the electrical panel INDOORS, instead of outdoors. Outdoor panels are far more prone to problems, and it’s easier to air seal one large cable coming through the wall than it is to seal a bunch of small ones. It’s possible to mount a panel recessed into a wall, and most residential electrical panels are sized to fit between studs for exactly this reason.
If you’re stuck having to put the panel outdoors, I’d establish a flat area for the panel to mount to, maybe some treated plywood, and run all the cables through the back of the panel. If these are all NM cables, you can use some duct seal (tar-like clay material) to seal the inside of the panel, then use canned foam from behind to seal the actual wall penetration. Another option that may work better is to run a few conduit stubs through the wall to a large pullbox mounted inside, then seal the wall to the exterior of the conduit with canned foam or caulk, and seal the interior of the conduit around the wires with duct seal.
Note that if you consider using an interior pullbox, you might as well just mount the panel inside to save a step and simplify things. I know that in some areas it’s common to install electrical panels on the exterior of the home, or in garages, but that’s not good practice: it’s always much better to install the panel within the conditioned space to avoid issues with corrosion and insect damage. Attached Garages are much better installation locations than outdoors too, but still far inferior to indoor installations.
Bill