I have a question regarding 2008 NEC 314.27[A], Outlet Boxes, which states...
"Boxes used at luminaire and lampholder outlets in ceilings shall be designed for the purpose and shall be required to support a luminaire weighing a minimum of 50 lbs."

Does this mean that the familiar round old-work boxes that are supported by the drywall ceiling with clamps are allowed to be used only for supporting lightweight, non-lighting related items, such as, smoke detectors, etc…?

I have heard this before, but am wondering if this is actually enforced in old-work situations?

Thanks