In 1991, the United States government made into law that owners of publicly accessible areas had to properly accommodate disabled persons also know as the Americans with Disabilities Act (ADA). ADA is not specific to lighting but does have regulations regarding standards for wall sconce projection space and hanging light clearance.
Section 4.4 of the ADA states that “objects projecting from walls with their leading edges between 27″ and 80″ above the finished floor shall protrude no more than 4” into walks, halls, corridors, passageways or aisles.
Lighting manufacturers responded to this law by creating less intrusive fixtures.