I've installed a few PV systems using flexible metallic conduit (FMC) through the attic to meet the "metallic raceway" requirement for DC conductors inside the building. Lengths range from 20 to 50 feet. These systems passed inspection, but they are rural.
Now, an electrician is telling me FMC is intended for equipment connections (short runs), and the maximum allowed length is six feet. I am certain I read somewhere that this maximum length somehow doesn't apply to PV, but now I can't find a reference. John Wiles' various publications say EMT and FMC meet the requirement, but he doesn't mention a length limit on FMC.
Anyone happen to know about this or have a link?