Also known as CMP cabling, a grade of cabling that is resistant to combustion and is used for horizontal cable runs in building plenums and vertical rises such as elevator shafts. A plenum is a horizontal space within a building that houses building components and allows the movement of air.
False ceilings are not considered plenums. Plenum cabling is less flexible and costlier than polyvinyl chloride (PVC) cabling. The external insulating jacket of plenum cabling is usually a fluoropolymer such as Teflon FEP.