Single and multiple-station smoke alarms shall be installed in the following locations:
In each sleeping room.
Outside of each separate sleeping area in the immediate vicinity of the bedrooms.
On each additional story of the dwelling, including basements and cellars but not including crawl spaces and uninhabitable attics. In dwellings or dwelling units with split levels and without an intervening door between the adjacent levels, a smoke alarm installed on the upper level shall suffice for the adjacent lower level provided that the lower level is less than one full story below the upper level.
When more than one smoke alarm is required within an individual dwelling unit, the alarm devices shall be interconnected in such a manner that the actuation of one alarm will activate all of the alarms in the individual unit. The alarm shall be clearly audible in all bedrooms over background noise levels with all intervening doors closed. Smoke detectors shall receive their primary power from the building wiring and shall have a battery backup. The bare ground in non-metallic sheathed cable is not allowed to interconnect devices for signal purposes.