1.2 In most houses the installation of smoke alarms or automatic fire detection and alarm systems, can significantly increase the level of safety by automatically giving an early warning of fire.

1.3 If houses are not protected by an automatic fire detection and alarm system in accordance with the relevant recommendations of BS 5839: Part 1 Fire detection and alarm systems for buildings, Code of practice for system design, installation and servicing to at least an L3 standard, or BS 5839: Part 6 Code of practice for the design and installation of fire detection and alarm systems in dwellings to at least a Grade E type LD3 standard, they should be provided with a suitable number of smoke alarms installed in accordance with the guidance
in paragraphs 1.4 to 1.22 below.

1.4 The smoke alarms should be mains-operated and conform to BS 5446 Components of automatic fire alarm systems for residential premises, Part 1 Specification for self-contained smoke alarms and point-type smoke detectors.
They may have a secondary power supply such as a battery (either rechargeable or replaceable) or capacitor. More information on power supplies is given in clause 13 of BS 5839: Part 6: 1995.

Note: BS 5446: Part 1 covers smoke alarms based on ionization chamber smoke detectors and optical (photo-electric) smoke detectors. The different types of detector respond differently to smouldering and fast flaming fires. Either type of detector is generally suitable. However, the choice
of detector type should, if possible, take into account the type of fire that might be expected and the need to avoid false alarms. Optical detectors tend to be less affected by low levels of ‘invisible’ smoke that often cause false alarms.

BS 5839: Part 6 suggests that, in general, optical smoke alarms should be installed in circulation spaces such as hallways and landings, and ionization chamber based smoke alarms may be the more appropriate type in rooms, such as the living room or dining room where a fast burning fire may present a greater danger to occupants than a smouldering fire.