Section 9.1.1/Gas Appliance Installation Requirements
NFPA 54 Chapter 9 covers gas appliance installation including clearances to combustibles, garage elevation, attic access, and service clearances.
Gas-fired appliances must be installed per the manufacturer's listing and instructions. Clearances to combustible materials must be maintained as specified on the equipment label. Appliances must be accessible for inspection, service, repair, and replacement. Appliances in garages must have the ignition source elevated at least 18 inches above the floor to avoid igniting gasoline vapors. Appliances in attics and underfloor spaces require access openings, walkways, a light, and a receptacle near the equipment.
Why this section exists
Gas appliances produce heat and open flames that can ignite nearby combustible materials if clearances are inadequate. The 18-inch garage elevation prevents gasoline vapors (heavier than air, pooling at floor level) from reaching pilot lights. Access requirements ensure appliances can be serviced throughout their lifetime. An inaccessible furnace in an attic is a maintenance hazard that can lead to deferred repairs and unsafe conditions.
What plan reviewers look for
Plan reviewers check the mechanical plans for appliance clearances to combustible construction. They verify garage equipment has the 18-inch elevation shown on the drawings. They check attic and crawl space installations for access openings of adequate size, walkways to the equipment, and a light switch at the access point. They verify the appliance manufacturer is specified so listed clearances can be confirmed.