Non-plenum rated cables may be run through a plenum space under what condition?

Non-plenum rated cables may be run through a plenum space under what condition?

• A. If they are installed in a plenum rated raceway
• B. If the building is not occupied
• C. If they are shielded
• D. If they are less than 3 feet from a heat source

Answer: (A)

Plenum spaces can spread fire and smoke quickly through the building’s air ducts, so cables running through them must meet strict fire-safety requirements. Non-plenum cables can be routed through a plenum space if they are enclosed in a raceway that is listed and rated for plenum use. That raceway provides the necessary containment and limits flame and smoke propagation, keeping the air-handling path safer. Occupancy, shielding, or proximity to a heat source don’t change the fire-safety performance of the cable itself; the raceway rating is what makes the installation acceptable in a plenum.

Plenum spaces can spread fire and smoke quickly through the building’s air ducts, so cables running through them must meet strict fire-safety requirements. Non-plenum cables can be routed through a plenum space if they are enclosed in a raceway that is listed and rated for plenum use. That raceway provides the necessary containment and limits flame and smoke propagation, keeping the air-handling path safer. Occupancy, shielding, or proximity to a heat source don’t change the fire-safety performance of the cable itself; the raceway rating is what makes the installation acceptable in a plenum.