Why not use plenum cable and circumvent the use of conduit and closed cable tray systems in return air spaces?
The use of free-strung, plenum-rated cable does not provide the physical security and support for the wiring that is achieved by installing a closed cabling infrastructure. CIT incorporates this standard to ensure that the installed communication cable performs as intended and to protect the health and safety of building occupants. UL-rated plenum cable burns at slower rate than standard PVC cable and produces a clear smoke that emits deadly toxic gases. The installation of a closed cabling infrastructure adheres to the NFPA 13 (National Fire Protection Agency – Code for sprinkler installations). This code requires that sprinkler systems be installed in plenum and concealed spaces that contain cables that are exposed in ceiling and sub-floor installations. The installation of a redundant sprinkler system will incorporate additional costs and will obstruct valuable space that is needed for other utility systems.
