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Voice alarms and robust standards: although voice alarm systems have been around for some time, the development of standards to support their use as fire warnings has happened more slowly. Bernard Laluvein examines the impact of the most recent standards in improving their reliability and integrity.

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WHEN INSTALLED IN A BUILDING, A VOICE ALARM (VA) system acts as the alarm output function of the fire detection system and, as such, must achieve a high degree of availability in readiness for fire emergency. Research has demonstrated that voice messages are more effective than conventional sounders in alerting people and directing them rapidly out of a building, because VA systems give clear instructions, tailored to the developing situation.

Although VA systems have been used in the evacuation of buildings for a number of years, the development of robust standards based on best needs for safety in case of fire has evolved more slowly. Recently, a number of new European product standards and a revision of BS 5839-8 code of practice have been published. The impact of these developments is reviewed below.

Revised BS code of practice

BS 5839-8, first published in 1998, has been used by the voice alarm industry for over 10 years. At the systematic review of this standard, the responsible BSI committee decided that it should be overhauled to adopt the same structure as BS 5839-1:2002 and introduce new thinking in the conception and implementation of VA systems. A group of industry experts assembled and revised BS 5839-8, which was eventually published in May 2008. Many of the recommendations in the 1998 edition of the code were transferred to the revised code. No major changes, except for some clarifications, were made to the recommendations for audibility and intelligibility of messages or to those for commissioning and maintenance of systems. However, a number of significant changes in other areas were made.

Need for voice alarm

Because of their effectiveness, VA systems should be used in all buildings where life safety depends on having a pre-determined evacuation plan. This covers most occupied buildings, including those where the use of traditional alarm sounders such as bells or electronic sounders may be deemed sufficient. However, in practice, the need for a VA system in a specific building will be determined by the authority responsible for enforcing applicable fire safety codes and/or by a fire...

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