A manual fire alarm system must be installed in Group B occupancies where the combined occupant load of all floors is how many or more?

In the context of fire safety regulations, Group B occupancies, which typically include business areas, are required to have specific fire protection measures in place based on the occupant load. The installation of a manual fire alarm system is mandated when the combined occupant load reaches a certain threshold.

A manual fire alarm system is crucial for alerting occupants in emergency situations, and its requirement at higher occupancy levels reflects the increased risk and potential for hazards associated with larger crowds. In this case, the correct threshold is 500 or more occupants across all floors. This ensures that in the event of a fire or emergency, there is a reliable method of alerting a significant number of people quickly and effectively, enhancing overall safety.

Establishing the threshold at 500 acknowledges the need for more robust safety protocols in environments where many people gather and work, as these situations require greater preparedness for evacuation and emergency response.

The other potential thresholds, such as 100, 200, and 1,000, do not align with the established safety codes that specify when a manual fire alarm system becomes a necessity for Group B occupancies.