Category A machinery space—TB/ALL.

The term Category A machinery space means any space and trunks and ducts to such a space that contains: (a) Internal combustion machinery used for main propulsion; (b) Internal combustion machinery used for purposes other than main propulsion where the total aggregate power is at least 500 brake horsepower; (c) Internal combustion machinery that uses a fuel that has a flash point of less than 43.3°C (110°F); or (d) One or more oil fired boilers or oil fuel units. [CGD 74-127, 41 FR 3842, Jan. 26, 1976]