Insulating electrical boxes on exterior walls

[pegasush]

I am looking for ways to insulate the electrical boxes. Typically, the boxes are contained in a poly box (??), which is taped to the poly air barrier. Unfortunately, these outlets always leak air to some degree. I have heard of installing foam insulation outside of the electrical box, inside the poly box, which should seal things up pretty well. Makes sense so far.

My concern is that urethane foams are pretty flammable. Is there any product which will work for this? Or is there a better way?

[kadoka]

We just used the spray foam insulation around the boxes from the inside of the walls. There is no insulation inside of the boxes themselves.

[Vector]

I generally use air-tite boxes, rather than putting a Lessco or similar around them, and then put a small amount of the foam (Hilti stuff) where the cable comes into the box.