(2) Additional Locations
(C) Where one or more lighting outlets are installed for interior stairways, there shall be a wall switch at each level, and landing level that includes an entry way, to control the lighting outlets where the stairway between the floor levels has six risers or more.
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Would this require a 3-way switching device in both an unfinished attic and basement?
I don't think it would because is clearly says "landing level that includes an entry way."