Limited combustible cable in plenum spaces

[Socket7]

I?m currently trying to sort out the confusion concerning the use of plenum rated communications cable in plenum space (w/ HVAC) and the statements in NFPA 13 and NFPA 5000 which now consider most standard plenum rated cable to be combustible, thus requiring they either be removed (if unused) or contained in metal conduit for new installations. The new standard per NFPA 90A, if I understand correctly requires the installation of cable listed as ? UL limited combustible FHC 25/50? in plenum spaces, assuming metal conduit is not used and avoiding installation of plenum sprinklers is desired. My question comes from the fact that it seems many people are ignoring this requirement and installing standard plenum cable. Is NFPA 13 being ignored for a reason? Has there been an addendum that I do not know about? Are there further stipulations and exceptions that I am not aware of that would allow me to specify the significantly cheaper plenum cable? The general consensus I'm getting is that cable manufactures aren?t selling much LC cable and plenum is still in high demand? Is NFPA 13 not nearly as broad as I am interpreting it to be? Please shed some light on this issue.