When multiple fire areas of Groups A-1, A-2, A-3 or A-4 have a combined occupant load, an automatic sprinkler system is required if the occupant load is:

The requirement for an automatic sprinkler system in commercial buildings is closely tied to ensuring safety in case of fire, particularly in areas with significant occupant loads. For Groups A-1, A-2, A-3, or A-4, which generally include assembly occupancies, the code specifies that when these areas have a combined occupant load of 300 or more, an automatic sprinkler system becomes necessary.

This threshold is determined based on the increased risk associated with higher numbers of occupants. A combined occupant load of 300 signifies that should an emergency arise, the potential for chaos and danger increases, necessitating the protection that sprinklers can provide. Sprinkler systems significantly reduce the threat of fire spreading and, when activated, can save lives by providing an essential line of defense until firefighters arrive.

The other choices reflect levels of occupancy that do not trigger the sprinkler requirement as defined by the applicable codes. Lower levels of occupant loads do not impose the same level of risk associated with fire, which is why the code has set the threshold at 300 occupants. Thus, it is crucial for anyone involved in building inspections to understand this threshold to ensure compliance and safety in assembly occupancies.