By definition, the plenum space (where plenum rated cable is used) usually includes the space above a drop or false
ceiling and below a structural
ceiling or below a raised floor, depending upon where HVAC
duct is located.
Given this definition, some inspectors will say that plenum
rated cable is requires ANYWHERE within the above-named spaces. Other inspectors insist that installers
may use PVC
cable as long as they are not entering an area of moving
Plenum Cable is often manufactured with Teflon
, while the non-plenum varieties are most often found to use PVC
and other toxic components. The composition
of the plenum rated cable allows it to produce less smoke than non-plenum cable when subjected to heat and fire.
The plenum rating requirement is intended to reduce the potential smoke inhalation
risk and toxicity to building occupants
during a fire