Theatres are SO touchy that you can't make your plans based upon the NEC.
You always need to touch base with the Fire Marshal.
The last theatre I worked on -- quite a while back -- the FM restricted PVC usage to below slab. The transition to EMT had to occur dang near flush with the slab.
PVC decays into cyanide gas and soot during partial combustion. Consequently many FM will not tolerate PVC since this result can be triggered by fires not started by the Low Voltage conductors.
Don't be surprised if plenum rated cables become necessary.
