Which type of enclosure is permitted for electrical equipment installed within a plenum space?

The selection of a metal enclosure or a nonmetallic enclosure for electrical equipment installed within a plenum space aligns with the safety regulations set forth in the National Electrical Code (NEC). Plenum spaces are areas designed for air circulation, typically found in the ceilings or floors of buildings, and they often require specific consideration due to fire safety and airflow.

Both metal and nonmetallic enclosures are permitted because they can be designed to minimize the risk of fire transmission and are capable of providing adequate protection for the electrical components within. Metal enclosures help in grounding and shielding, while nonmetallic enclosures can be designed and constructed from materials that do not contribute to fire growth or smoke release, crucial in maintaining safety in spaces that deal with heated air circulation.

The code provides flexibility in material choice, recognizing that both types can meet safety standards when properly installed and maintained. Thus, having the option to use either type of enclosure allows for greater adaptability to different installation conditions and compliance with local regulations.