A fire alarm system must include a visible notification device when the ambient sound is greater than what level in dBA?

The correct answer is based on the requirements set forth in the National Fire Protection Association (NFPA) standards, specifically NFPA 72, which outlines the criteria for notification appliances in fire alarm systems. When ambient sound levels exceed 105 dBA, relying solely on audible alarms becomes insufficient because the sound from the alarm may not be heard, especially in environments with significant background noise.

To ensure occupants receive adequate warning in situations where the sound level is elevated, a visible notification device—such as strobes or flashing lights—must be incorporated into the fire alarm system. This ensures that even those who may not hear the alarm due to high ambient noise can still be alerted effectively, thereby enhancing the overall safety and effectiveness of the fire alarm system in alerting all individuals to the potential danger.

Understanding this threshold is crucial for compliance with safety regulations and for ensuring that fire alarm systems function as intended in various environments, particularly those known to have high noise levels.