Sealing electrical boxes after construction
So after you have addressed all other issues, and you are down to the last bit of air sealing, and air is coming through the electrical box, what is the best way to seal them?
There seem to be three options, with option 2 being the preferred. Is this correct? Below are some questions about using option 2…
a) foam, ensuring that NONE of the foam encroaches on the volume of the electrical box. Fire rated foam, with the nozzle in the box opening, and trimming away any that expands into the box seems like it would be the quickest way. Is this code compliant? The following post seems to indicate anything in the box could be considered a code violation…
and this post unecivocably states it is:
b) From the post below, it seems high temp fire rated caulk is preferred. Does this caulk stay in place in the hole through which the wires come after the caulk is cured and when the electricians move wires around to terminate the devices? If you keep it from encroaching on the box, is there any code issue associated with applying this to the knockouts, both the unused open ones and the ones through which wires come?
c) Interior applied putty pad – sometimes called “box inserts.” Seems like it might be quick, but according to this they are not approved for non-metallic boxes, which many residences have.
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