NEMA Publishes New Standard for Air-Sealed Outlet Boxes


ROSSLYN, Va., April 12, 2017—Today, the National Electrical Manufacturers Association (NEMA) published a new standard, NEMA OS 4-2016 Requirements for Air-Sealed Boxes for Electrical and Communication Applications. This standard establishes a performance test and classification scheme for electrical outlet boxes, wall boxes, ceiling boxes, and floor boxes designed to reduce air leakage through them and their installed interface with the building structure.

“NEMA OS 4 provides the outlet box industry a much-needed and standardized set of metrics. It gives building designers assurance that boxes made to this standard will provide the design features needed to effectively seal air barrier penetrations in order to comply with building and green energy codes,” according to David Kendall, chair of the NEMA Outlet and Switch Box Section. “Our industry anticipates that these boxes will also reduce potentially undesirable effects from using unspecified sealing techniques.”

NEMA OS 4-2016 is the first industry standard dedicated to testing electrical outlet boxes for their performance in maximizing energy efficiency in building structures. It is available for $60 in hard copy and as an electronic download on the NEMA website.


The National Electrical Manufacturers Association (NEMA) represents 350 electrical, medical imaging, and radiation therapy manufacturers at the forefront of electrical safety, reliability, resilience, efficiency, and energy security. Our combined industries account for more than 400,000 American jobs and more than 7,000 facilities across the United States. Domestic production exceeds $114 billion per year and exports top $50 billion.