The National Electrical Manufacturers Association (NEMA) published NEMA OS 4-2016 Requirements for Air-Sealed Boxes for Electrical and Communication Applications, a new standard that establishes a performance test and classification scheme for electrical outlet boxes, wall boxes, ceiling boxes and floor boxes.
The standard is designed to reduce air leaks through the boxes and their installed interface with the building structure when installed as intended for normal use.
Besides external walls and ceilings in a building, uninsulated interior walls and interior floor-ceiling cavities not designed specifically for air exchange, present pathways for air leakage. Even though air barriers are not commonly installed here, consideration should be given to using effective sealing techniques at wall, ceiling, and floor penetrations in these areas.
The classification scheme in this standard meets the intent of the International Energy Conservation Code (IECC) and covers boxes installed in walls, ceilings, and floors where an air barrier is required. To see the standard in full, please click here.