________ shall be permitted to support the wiring methods and equipment in other spaces used for environmental air (plenum).

Metal cable tray systems are designed to provide support for wiring methods and equipment, particularly in areas where environmental air is utilized, such as plenum spaces. These systems are made from materials that can withstand the mechanical stresses often encountered in such environments, ensuring both durability and reliability. Additionally, metal cable trays have specific configurations that facilitate adequate ventilation and heat dissipation, which is crucial in preventing overheating of electrical equipment within plenum spaces. The use of metal trays can also provide an effective path for grounding, thus enhancing safety.

In contrast, nonmetallic wireways and surface nonmetallic raceways, while useful in various wiring applications, may not meet the same rigorous standards required for supporting wiring in plenum areas. PVC conduit, while providing good protection for wiring, is generally not suitable for plenum use due to its combustion characteristics and potential for releasing harmful substances when exposed to fire. Therefore, metal cable tray systems are uniquely qualified to support wiring methods and equipment in these sensitive environments.