Installing Meter Panel on Wall With Exterior Foam Insulation
Wunderbar
| Posted in Expert Exchange Q&A on
Hello
We are installing a new meter main panel on the house and am wondering the best practice for doing this with 3” of exterior foam insulation.
I’ve got zip sheathing, 3” of polyiso, 3/4” rainscreen, siding. It’s a meter main combo box with underground service. Has one service wire to an interior 200a panel that goes through the back.
I’m thinking I can just install it directly to the zip sheathing and build a channel under it for the conduit. Once the exterior foam and siding are installed it will be recessed into the wall almost flush with the siding. I’ll still have interior insulation in that location as well.
Thanks in advance
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Replies
I'd advise against recessing the meter into the wall, which can pose future problems, and may be disallowed by your utility company too. My preference is to leave a hard surface (usually 3/4" plywood with a flat siding material over it to match the color of the rest of the siding, such as using one of the pieces of sheet that Hardi makes that matches their siding). Either fasten this through the foam with long fasteners of heavy-ish (1/4") diameter, or, better yet, put in some "hard points" using some ripped framing lumber between the studs and the hard backer board to make things rigid. This avoids disrupting your continuous insulation, keeps the electrical stuff on the surface, and provides a good mounting surface so that you won't have any issues with the structure.
Run a piece of EMT conduit out the back to tie into your main panel, assuming it's "right there" on the other side of the wall. If you'll be using something like SER cable, then bring it into the back of the meter box and seal around it with canned foam, taking care to keep the foam out of the meter box. If you use conduit (my preference), you can seal the interior with duct seal, or stuff in mineral wool until it's compressed and "hard". While mineral wool isn't quite the air barrier duct seal is, I much prefer mineral wool for this since it's a lot easier to remove in the future if you need to do any work. If you really want a good air seal too, cover the conduit with a fire putty pad on the box interior, being careful to mold the putty around the individual wires and top of the conduit fitting without creeping out into the interior of the box too much.
Bill