Kerova

Checker · Fire alarm · BS 5839-1

Fire alarm sound level checker

Choose the type of area and, if you have it, the background noise. You get the minimum alarm sound level. Enter a reading from your sound meter to see whether it passes. Sounder levels are in dB(A).

Your figures

dB(A)

Background noise that lasts more than 30 seconds, measured with a sound meter. Leave blank if you do not have it.

dB(A)

Enter a reading to check it against the requirement.

Result

Choose an area to see the requirement.

Working

general areas: the higher of 65 dB(A) and background + 5 dB(A)

  • General areas: 65 dB(A), or 5 dB(A) above the background noise if that is higher. Use background noise that lasts more than 30 seconds, measured with the doors closed.
  • Sleeping areas: 75 dB(A) at the bed head, with the doors shut.
  • Stairways, or enclosures under 60 m² (not corridors): 60 dB(A).
  • The alarm sound should not go above 120 dB(A) anywhere people can normally reach. This figure is from one maker's guide and one other source, so check it.
  • A normal door cuts the sound by about 20 dB(A) and a fire door by about 30 dB(A). These are rough figures, so measure with the doors shut.

Source: BS 5839-1, as set out in the FIA guide to the 2025 edition and panel makers' design guides.

Measure the alarm at the point with the lowest level, such as the bed head or the far end of a room, with all the doors shut.

For guidance only. Always check against the current edition of the standard and the manufacturer's data.

Built by the engineer behind Kerova, certificate software for fire and security firms.