Plenum cable is electrical cable that is laid in the plenum spaces of buildings. In the United States, plastics used in the construction of plenum cable are regulated under the National Fire Protection Association standard NFPA 90A: Standard for the Installation of Air Conditioning and Ventilating Systems.

What is a plenum cable used for?

Plenum rated cable has a special insulation that has low smoke and low flame characteristics. Plenum cable is mandated to be installed in any "air handling" space. For example, most large office buildings use the ceiling to return air to the AC unit.

What is the difference between plenum and non-plenum cable?

Plenum-rated cable has been manufactured to withstand higher temperatures in the event of a fire and does not cause the same level of smoke or toxicity when burning. Non-plenum does not have these characteristics, and as a result costs much less (usually half as much).