In the UK many people die or are injured in domestic fires every year, many of these are from smoke inhalation. These figures could be reduced by installing and maintaining domestic smoke alarms.

Where are self-contained smoke alarm systems required?

• new dwellings
• extensions to existing dwellings
• roof conversions

Self-contained smoke detector is not recommended for use in kitchens, garages or places where steam, condensation of fumes could give rise to false alarms. More appropriate and effective detectors area available for such situations, eg heat detectors.

It is also recommended that detectors be interlinked to form a system and not independent units. Also, smoke detectors may be wired to a lighting circuit, this is so that if the lighting fails then so will the alarm system and it is very likely that a failed lighting system will be repaired quickly.

Choosing a smoke detector

Domestic smoke detectors come in two basic types:

• Ionization Smoke Detector
  These work by measuring the reduction of an electrical current when smoke particles enter a special chamber.
• Optical Smoke Detector
  These contain a small photoelectric cell, which triggers the alarm when the beam is disturbed by smoke.

Research has shown that ionising detectors often are a little quicker to react to hot blazing fires than optical detectors. While optical detectors are better at detecting smouldering fires of the sort that might be started by a cigarette having fallen down the back of a sofa or chair. This means that an ionising detector might be better if situated in a corridor near a kitchen as it is less likely to be set off by burning toast, but would react quicker if the toaster were on fire. However, there is not a lot to choose between either Ionization of Optical smoke detectors.

When purchasing a smoke detector ensure it complies with a British Standard or the International Standard Organisation (ISO) standard. A self-contained smoke detector must comply with British Standard 5446 part 1 1990, for automatic fire detection, and to British Standard 5839 part 1 1988, for alarm systems.

Never buy a second-hand smoke detector. Always look for the British Standard kite mark or the CE mark.

Smoke detector can be powered

• By batteries in the unit
• From mains supply
• From mains with battery back-up

Mains wired with battery back-up is a requirement for compliance with Building regulations in flats and houses.