Caulking from inside of box?

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ESolar

Senior Member
Location
Eureka, CA Humboldt County
Occupation
Electrician/Contractor
Came across some standard receptacle boxes where the NM entry holes (used and unused) were caulked from inside the box. Looks like the Quad Max caulk that I use for some applications (a Silane Modified Polymer), although no way to really tell. I don't see where the code says anything about that. It's not significantly reducing volume, and its limited to the back top and bottom openings. Probably sealed for air or ants.
 
The energy code of the IBC would require boxes that penatrate the air barrier to be rated for installation in the barrier, the listing and installation instructions of the box would require that the cable entries be caulked.

The air barrier shall be installed behind electrical and communication boxes. Alternatively, air-sealed boxes shall be installed.
 
Only penetrating sheetrock into wall cavity. But this issue is code related to electrical. I think that that caulk has a flashpoint of 107 degrees C (225+ F). That is similar to silicone, that I see others suggesting is not really an issue. It seems like less of a problem than highly flammable foam outside the box that penetrates (to some extent) though the NM pass throughs and into the box.
 
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ESolar said:
Only penetrating sheetrock into wall cavity. But this issue is code related to electrical. I think that that caulk has a flashpoint of 107 degrees C (225+ F). That is similar to silicone, that I see others suggesting is not really an issue. It seems like less of a problem than highly flammable foam outside the box that penetrates (to some extent) though the NM pass throughs and into the box.
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Polystyrene foam is highly flammable but I don't know if it is allowed inside a building.
 
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