Sealing electrical box air leaks

[David Meiland]

Is there a NEC-approved method or material for sealing air leaks into electrical boxes? I have seen insulators use canned foam (a gun with a metal nozzle that allows for fairly precise work) to squirt a bit of foam into the wire entry hole, from the inside. A tiny bit of foam ends up inside the box, most of it outside (and a diligent worker can scrape off what . There are other caulk/sealant materials that would probably also do the job. I have personally used thin sheets of clay to soundproof electrical boxes from the outside, before the wall was closed.

Any thoughts on this? I have a customer who is highly motivated to reduce the air leakage in parts of her house, and quite a bit is coming from electrical openings. Doing something that is not code-approved is not an option.

[John Kogel]

Up here you buy poly covers that fit over the back of the box with a gasket around the front. But we use the CEC.

[David Meiland]

That's not a retrofit, though... right?

[tim5055]

That's not a retrofit, though... right?

The foam plate covers are. Available at your favorite big box store.

Frost King Foam Electrical Outlet and Wall Plate Insulating Kit

[Scottpat]

The foam gaskets work great and would be a whole lot easier, cleaner and safer than squirting foam.

[mlparham]

The foam gaskets work great and would be a whole lot easier, cleaner and safer than squirting foam.

I agree with Scott. My house was built in the mid 80's. I could feel air entering through the receptacles by placing my hand next to them. The foam gaskets that Scott refers to work great to seal around the box.

[David Meiland]

Hmmmm... those gaskets are uniformly regarded by energy auditors to provide little air-sealing. Here's an image of a receptacle that has a foam gasket behind it. This is during a blower door test in cold weather. You can see air leaking in and cooling the drywall, and cold air has also cooled the receptacle itself (because it has air pathways through it), but the trim plate is warmer (and nicely uniform) because it's insulated.

In spite of that, I put them in my house. They were giving away handfuls of them at the county fair, so I got a bunch.

We may end up sealing between the drywall and the box, and putting kid protectors in the unused outlets.

Click to Enlarge

32.8 KB

[Ben H]

If you really want to seal them: Caulk the box to the drywall, it sometimes takes a couple spins depending on how bad the cutout is. Kill the juice and hit the wire penetration with fire-stop foam. I have one of the pro guns that can leave the can on for long periods of time without drying up. Whenever I paint a new room, I always seal up the outlets and switches. If done correctly this will seal them 100%.

Here is a shot from one I did back in November.

Click to Enlarge

43.87 KB

[Nolan Kienitz]

Then there are the "can lights" in the ceiling. They have plenty of holes and slots on the can as a big path for air movement.

I've been putting in "dux-seal" (electrical clay or putty) to seal the holes to help minimize the air flow.

[Tom Raymond]

Kid protectors left in for long periods of time will compress the contacts in the receptacle. At best cords just fall out, at worst they arc, a lot.

I had to replace all of the receptacles in my son's room when we switched the decor from little boy to little man.