Under unobstructed construction, the distance between the sprinkler deflector and the ceiling shall be a minimum of 1 in. (25 mm) and a maximum of 12 in. (300 mm) throughout the area of coverage of the sprinkler. The requirements of 10.2.
The purpose of the “18-inch rule” is to prevent storage or any other obstruction from interfering with the spray of water from a sprinkler head during a fire. It is intended to prevent a situation in which the obstruction is within 18-inches of the ceiling and might be between the sprinkler head and the fire.
To comply with NFPA 13, sprinklers are required above the obstruction at a distance not less than 1 in. and not more than 12 in. from the ceiling above, assuming unobstructed construction.
The answer is that you should follow the general obstruction rules of NFPA 13. For obstructions below 18 inches for standard pendent and upright spray sprinklers this means that as long as the obstruction is less than 4ft (1.2 m) wide that it is not considered an obstruction.
In a nutshell, NFPA 25: Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems says that objects that can block a sprinkler's spray must be at least 18 inches away from the deflector.
The 18-inch applies only to areas that have sprinklers installed. Picture a horizontal plane parallel to the ceiling that is 18 inches below the sprinkler heads. Nothing should be in that area between the bottom of the sprinkler heads and the imaginary horizontal plane parallel to the ceiling that is 18 inches below.
All storage, regardless of the type, shall be kept at least 24 inches below a ceiling in non-‐sprinklered areas and at least 18 inches below the ceiling in sprinklered areas of the building.
5.2. 1 of NFPA 13, which states that the distance from the sprinkler to the wall can be no more than one-half the allowable distance between sprinklers. The max distance between standard spray sprinklers in light hazard settings is 15 ft. (4.6 m) (with exceptions for light-hazard, combustible concealed spaces).
3.2.3 “The Four-Foot and Wide Obstruction Rule”
For obstructions wider than 4 feet (1.2192 m), sprinkler protection is required below the obstruction with deflectors to be located less than 12 inches (0.3048 m) from the bottom of the obstruction.
All standard sprinkler heads—pendent, upright, and sidewall—have the same minimum sprinkler distance from walls: four inches. For sidewall heads, that's the distance from an end wall (10.3. 4.3.
NFPA 101 – Life Safety Code: Headroom is generally required to be at least 7 feet 6 inches, however, projections are allowed as long as a minimum of 6 feet 8 inches of headroom is provided at these projections. The code states that the measurement is taken from the finished floor and allows a tolerance of -3/4-inch.
» All sprinklers need to be quick-response standard spray or extended coverage pendent or upright sprinklers. » The ceiling height cannot exceed 20 feet. » The maximum spacing and area of protection cannot exceed the maximum spacing requirements for light hazard occupancies provided in Table 10.2.
3.1, 18.4(d) and 19.1.2.3, where the maximum ceiling/roof height is 40 feet.
(1) Provide and maintain 12-inch clear in back to walls or any other obstruction, 18-inch clear on each side, and 36 inches clear in front of all riser piping, equipment, and appurtenances.
The sprinklers spray at an angle of approximately 45 degrees. So of your light fixture is 4 inches deep, then you should keep them at least 4 inches away from the sprinkler heads.
They provide protection for the sprinklers - making them less prone to accidental knocks, tampering, and the potential water damage that can result. They simplify sprinkler design at clouds and other design features as the sprinklers are located above the dropped ceiling.
For sidewall sprinklers, the rule applies if the obstruction is within 18 inches below the sprinkler deflector. It says that the maximum distance from the sprinkler deflector to the obstruction is the smaller of four times the largest dimension of the obstruction or 36 inches.
NEC Section 110.26(A) requires a clear space at least 30 inches wide and 36 inches deep if the equipment is likely to be worked on while energized. This space is necessary not only to allow workers room to perform tasks but also room to move if something goes wrong.
9.5. 4* Storage cabinets shall not be required by this code to be ventilated for fire protection purposes. 9.5. 4.1 If a storage cabinet is not ventilated, the vent openings shall be sealed with the bungs supplied with the cabinet or with bungs specified by the cabinet manufacturer.
NFPA 72 requires all fire alarm systems, including equipment used for monitoring, to have 24 hours of backup power. If an IP communicator is used for monitoring, the internet equipment must be connected to a backup power supply capable of providing power for a minimum of 24 hours.
Check your system's design.
Keep the spray at least 2 feet away from the house.
5.1. 1.2 are met, sidewall sprinkler deflectors shall be located not more than 6 in. (150 mm) or less than 4 in. (100 mm) from ceilings.
Sprinklers shall be located a minimum of 4 in. (100 mm) from a wall.
Hanging Teaching Aids, Child Prepared Art work, etc. from the Ceiling ( IFC 703.3) Do not attach anything to a light fixture, fire alarm sensors, fire strobe lamps, sprinkler heads, or overhead pipe runs. Proper T-grid hangers are required to keep the integrity of the plenum rated ceiling.