Plenum Cable: Plenum cables are the electrical or telecommunication cables (or wires) which are installed in environmental air spaces in the interior of many commercial and residential buildings. It is common practice to route communication cables and the like for computers, data devices, and alarm systems through plenums in building constructions. If a fire occurs in a building which includes plenums or risers, the non-fire retardant plenum construction would enable the fire to spread very rapidly throughout the entire building. Typically plenum data cables have two or more pairs of insulated conductors in a common jacket. The insulation can be made of several types of flame retardant insulation. A plenum is defined as a compartment or chamber to which one or more air ducts are connected and which forms part of the air distribution system of the structure. Plenum cables have a plurality of twisted pair conductors surrounded by a jacket. The twisted pairs generally all have the same twist or substantially the same twist. A typical and widely used flame retardant insulation for conductors in data plenum cables is fluorinated ethylene-propylene.
Category 5 plenum cable made of jacketed twisted pairs of insulated conductors has to satisfy a number of electrical requirements set by the EIA/TIA specification 568A.