In private mode systems, what is the audibility requirement?

Private mode signaling is used in locations not open to the public (e.g., hospitals, certain office buildings). The audibility requirement for private mode differs from public mode.

NFPA 72 (2022), Section 18.4.5.3:

"For private mode audible appliances, the sound level shall be at least 10 dBA above the averageambient sound level..."

This ensures the signal is heard clearly in the intended space without exceeding what’s necessary.

Correct answer: C. 10 dBA above ambient

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