ACCL 12 AWG/2 Conductor Shielded Plenum Fire Alarm/Security Cable, Solid, FPLP, Spool, Red, 1000ftPlenum rated cable is made specifically for commercial installations. In buildings, there will be an area between floors or above office areas for heating cooling airflow called the Plenum. If an office were to catch fire, this plenum area could easily allow the spread of the fire to more floors or across the entire building. Cables that do not have a jacket rated for in wall or plenum use could actually cause the fire to become more intense.