In a fire, the quality of the announcement can decide how quickly people move. Voice evacuation systems are designed for exactly that moment: to deliver clear, correct instructions to the right people, even if part of the building or the power supply has failed. This guide covers how they are designed for factories, IT parks and hospitals, three very different environments.
Key takeaway: a voice evacuation system is judged by what it does under failure: whether people understand it, whether it covers the right zones and whether it keeps working when power or cables fail. Design for those conditions, then test them.
If you are still deciding whether you need one, start with our comparison of the PA system vs voice evacuation system.
Zoning and message strategy
Zones
Zones should follow fire compartments, floors and escape routes. A fire alarm panel decides which zones receive which message, so the zoning of the alarm and the speaker system need to match. If you are working on the detection side, our guide to addressable vs conventional fire alarm systems covers how the panel is organised.
Alert, evacuate, all-clear
Most systems use three types of message.
- Alert. Tells occupants in nearby zones that an incident has been detected and to prepare, with staff following their emergency procedure.
- Evacuate. Instructs occupants to leave by the nearest safe route.
- All-clear. Confirms the end of the emergency.
Phased evacuation
In tall buildings and hospitals, evacuating everyone at once may be unnecessary or even unsafe. Phased evacuation moves occupants of the fire floor and the floors next to it first, while others receive an alert. Hospitals add another layer: patients cannot all walk out, so messages often target staff with coded announcements and horizontal evacuation to a protected area.
Language and wording
Use short, calm sentences in the languages your occupants use, such as English, Hindi and Marathi. Record messages professionally, and agree the wording with your safety officer.
Intelligibility in noisy plants and large atria
- Factories. Machines produce noise that can drown out speech. Measure the background noise, then design for enough level above it, using many well-placed speakers or horn speakers where appropriate. Add flashing beacons so that people who cannot hear the message see an alert.
- IT parks and offices. Open-plan floors and glass atria create echo. Many low-power ceiling speakers usually give clearer speech than a few powerful ones.
- Hospitals. Corridors, wards and operating theatres have different needs. Some areas need quiet, localised messages, and others a building-wide alert.
- Measure it. Intelligibility can be tested with measurement tools during commissioning. Do not rely on someone saying it sounds fine.
Redundancy, cable survivability and power backup
- Supervision. Amplifiers, speaker lines and microphones are monitored, and any fault is reported to the fire panel.
- Amplifier redundancy. A spare amplifier takes over automatically if one fails.
- Loop wiring. Speaker circuits wired as loops keep working if a cable is cut at one point.
- Fire-resistant cable and routing. For circuits that must keep working during a fire, fire-rated cable and protected routes are used, as your design requires.
- Power backup. Batteries supply the system for the required period if mains power fails, with enough capacity left to broadcast the evacuation message at the end of that period.
- Separate failure modes. Avoid having one fault disable both the alarm and the announcement system.
Requirements for voice alarm systems come from the standards and the approval authority for your project. Confirm them with your fire consultant, and see our NBC 2016 overview for how the national code approaches alarm and public address requirements by occupancy.
Commissioning tests and routine checks
At commissioning
- Test every zone with each message, and confirm correct zones receive the correct message.
- Test the fire-alarm trigger, manual microphone override and priority over background audio.
- Measure intelligibility in representative areas, including the noisiest and the most reverberant.
- Simulate faults: cut a speaker line, switch off an amplifier and remove mains power, and check that the system reports and recovers as designed.
- Check battery capacity and the time the system runs on backup.
Routine checks
- Daily: panel shows no faults.
- Monthly or quarterly: test messages to selected zones, in coordination with occupants.
- Annually: full functional test including battery and fault simulation.
- After any building changes: recheck coverage and intelligibility.
Our fire alarm maintenance checklist can be adapted to include your voice evacuation system.
Talk to KBI
Request a voice-evacuation design proposal. Send us your floor plans and a note on use, noise and occupancy. KBI will propose zoning, speaker layout, backup and testing. See our Public Address System and Fire Detection & Alarm System pages or contact us.