Air Sealing Exterior Wall Outlet Tutorial 29Dec2020 

The problem here is that using foam in the knockouts is against code because most foam is flammable. Even fire rated foam is recommended only for outside the electrical box. The box is your first line of defense in case of sparks or overheating of wires. The foam could melt, smolder or catch on fire. Not saying now, but years in the future due to age. Fire rated Silicone might be a better solution as I have seen some electricians use that for knockout plugging, making sure to keep the majority of the silicon outside of the box.

2 minute video in over 22 minutes. Great idea. One of many. Really in need of the KISS principle [Keep It Simple, S#$^^#].

You cant do this with the foam. It is flammable and it reduces the available space in the box for the fill according to the nec.

Air sealing an electrical box in a house in VT is like squirting a squirt gun into the ocean. Most towns here have no inspectors and builders are running wild. Air leaking into a switch box is probably the least of the problems with your home. Furthermore, you don’t want to air seal your home at all if you don’t have mechanical ventilation.

Is that firestop foam & caulk

What type of foam did you use? Open cell closed cell, something else? Great stuff?

Um.DONT do this inside the electrical box.

There are foam gaskets that go over the outlet and switches, underneath the wall plate. They are cheap, easy to install, and work great. Also, keep the knockouts from the gasket and put them onto the prongs of childproof outlet plugs. Insert these plugs into any unused outlet, especially on outside walls.

tooooooooo long. too much babble. get to the point.