armored cable running through ductwork to supply power to a light in the attic

Has anyone ran into issues or have advice regarding armored clad wires being run through air return stud cavities? It runs inside the air return to the attic to power the attic lighting. Also, if anyone has any cited information regarding TV cable wires that penetrate through a B-vent and run vertically up the vent (inside of it) to supply cable to two bedrooms on the upper floors. Thanks a ton!

AC cable is permitted in those stud spaces, NM is also permitted. NM is limited in that it can only traverse the stud space perpendicular to the studs.

Nothing is allowed to “penetrate” a B-vent.

For the rest of us what’s a B vent?

A double-walled metal flue pipe used for venting gas fired appliances.

Thanks guys… The support is much appreciated.