Plenum
Plenum refers to an air chamber in a heating, ventilation, and air conditioning (HVAC) system or to the space above the ceiling or below the floor used for air circulation. In many buildings, the plenum space is often used to route conductors and cables.
Plenum-rated describes a special type of conductor or cable which is approved/rated for use in a building plenum space. These types of conductors are specially insulated, giving them low flame- and smoke-producing properties. Non-plenum rated cables may also be routed in a plenum space, if they are enclosed in conduit that provides fire-resistant properties.
SHARE