Significantly efficient to the Deaf or really hard of hearing, especially in situations wherever Visible alarms may well go unnoticed. EN54-23 is a European Normal for visual alarm units, which aims in order that their light-weight output is measured uniformly across Europe. This common is fairly new, pushed partially via https://www.firesense.co.uk/type/conventional-fire-system/conventional-sounders-vids-vads/