Final answer:
Sprinkler heads should be installed within 1 to 12 inches below the ceiling to comply with NFPA 13 Standard. Any installation with sprinkler heads more than 12 inches below the ceiling is generally incorrect, unless specifically designed and approved.
Step-by-step explanation:
The correct placement of sprinkler heads in relation to the ceiling, which is a topic commonly addressed in fire protection engineering and codes. In general, the National Fire Protection Association's NFPA 13 Standard on the Installation of Sprinkler Systems typically specifies the positions of sprinkler heads.
For standard pendent and upright sprinklers, NFPA 13 requires that the deflector be positioned at a minimum of 1 inch and a maximum of 12 inches below the ceiling. If sprinkler heads are located more than 12 inches below the ceiling, they are generally considered to be incorrectly installed unless specified by a design that has been properly approved.