Can caulking be used to air seal electrical boxes? – GreenBuildingAdvisor

Yes, you can seal around the exterior of the box with canned foam or regular caulk. My preference is to use the red silicone high-temperature caulk to seal holes in boxes though. You want to keep any of these materials outside of the box as much as possible. You don’t need fireblock caulk here, you need that in fire rated WALL assemblies. If you don’t have a fire rated wall assembly, you don’t need to worry about that part. Note that in typical residential construction, the only requirements for fire rated assemblies are the wall dividing the living space from an attached garage.

You can also use the so-called “putty pads” of red fire stop material. These are self adhesive and work well (and are also great for sound proofing), but they aren’t cheap.

Note that you do NOT want to use “intumescent” fire stop caulk here. That stuff is intended to expand when it gets hot, you’re better of with regular silicone caulk here (or the high temp red silicone I mentioned earlier).

Bill