Alarm Sound Levels

Audible warning

General accessible areas

At least 65 dB(A), assessed with doors shut.

Bed-head

At least 75 dB(A) where the alarm must wake sleeping people.

Background noise above 60 dB(A)

Aim for at least 5 dB(A) above the background level.

System resilience

At least two fire alarm sounders in a building and normally one per fire compartment.

The browser calculator is a free-field estimate. Commissioning measurements in the real building remain essential.

Visual alarm devices

• Consider visual alarms where ambient noise is very high or hearing protection is likely to be worn.
• Use devices conforming to the applicable product standard and position them so the signal is readily visible.