22 CAR § 111-1404. Cabling standards

(a) All cabling shall conform to the latest industry standards applicable to the specific system at the time of installation. (b)(1) Cabling not installed in a closed conduit system should be specified to be plenum rated cabling regardless of whether the space is a return air plenum or not. (2) This will eliminate the need to replace the cabling system if the HVACR system is renovated to a return plenum system. (3) In addition, plenum rated cabling generally develops less smoke and has a reduced flame spread in the event of a fire, thus improving the fire safety of the building.