NFPA 72 code sections · Devices & Signal Flow: How the Panel Hears and Speaks
Speaker (voice evacuation): the panel tells people what to do, not just that something is wrong
In an emergency voice/alarm communications system the panel's output is a speaker instead of a horn. On alarm the panel plays an alert tone followed by a pre-recorded evacuation or relocation message to the speaker circuits the sequence of operation selects — the fire floor, the floors above and below, or the whole building — and a firefighter can take over with the live microphone, which has priority over recorded messages. The messages must be intelligible, not just audible, in every space where people are expected to understand them.
NFPA 72 reference
Chapter 24 — Emergency Communications Systems
24.4.2 In-Building Fire Emergency Voice/Alarm Communications Systems (alert tone and message, selective or all-call operation, live voice priority at the fire command center); 18.4.11 voice intelligibility; 10.11.1 response time
References use NFPA 72 2019/2022 numbering — section numbers can shift between editions, so confirm in the edition your AHJ has adopted.
On the job, step by step
- A smoke detector alarms on the 12th floor of a high-rise.
- The panel plays the alert tone and then 'Attention: a fire emergency has been reported on the 12th floor. Please proceed to the stairs and relocate to the 9th floor' on floors 11, 12 and 13.
- Other floors hear nothing yet; the sequence of operation keeps them in place to avoid crowding the stairs.
- The incident commander arrives at the fire command center, keys the microphone and gives live instructions — the panel mutes the recorded message on the selected floors while she speaks.
- After the event the panel is reset and the speakers go silent.
Quick check
1. In a voice evacuation system the panel sends speakers:
2. Live voice from the fire command center:
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