Fire foam

[olly]

I see some electricians installing fire foam in every hole and box when they are done with rough in on a residential building. Is that code now?

 

[Buck Parrish]

It's a building code. In some areas the insulators do it before the framing inspection. Electricians do it, too.

 

[coffeebean]

300.21

 

[Coppersmith]

I'm only required to foam penetrations between floors (including the attic). Horizontal stud penetrations and holes in block for boxes don't require foam (from me. The insulators might do it.)

 

[hbiss]

I see some electricians installing fire foam in every hole and box when they are done with rough in on a residential building. Is that code now?

300.21 Spread of Fire or Products of Combustion

Electrical installations in hollow spaces, vertical shafts, and ventilation or air-handling ducts shall be made so that the possible spread of fire or products of combustion will not be substantially increased. Openings around electrical penetrations into or through fire-resistant-rated walls, partitions, floors, or ceilings shall be firestopped using approved methods to maintain the fire resistance rating.

You have to tell us what you consider "fire foam". In most residential installations, the use of non-expanding insulating foam is allowed for vertical penetrations. It's really draft stopping to eliminate the chimney effect of hot gases and smoke from traveling from floor to floor. Then there are energy codes that require the sealing of many openings.

300.21 really only addresses fire-rated assemblies where you would use the red fire stop or other actual intumescent fire stopping materials that stop the burning of the cable up through to the next level.

-Hal

 

[GoldDigger]

I'm only required to foam penetrations between floors (including the attic). Horizontal stud penetrations and holes in block for boxes don't require foam (from me. The insulators might do it.)

In many parts of the country the Energy codes require a lot more insulation, including steps to reduce air infiltration at any penetrations in the exterior walls, including interior switch and receptacle boxes in those walls. Possibly some workers find it easier to apply such rules to all boxes instead of trying to figure out which ones actually require it.