Fitting Smoke Alarms

Where to fit Smoke Alarms

Types of Smoke Alarm

There are two main types of smoke alarm currently available - ionisation and optical. There are strengths and weaknesses of both types.

Ionisation: These are the cheapest type available, they are very sensitive to small particles of smoke produced by flaming fires and will detect this type of fire before the smoke gets too thick. They are, however, a little less effective where there is a slow burning or smouldering fire, which gives off larger quantities of smoke before flaming occurs.

Optical: These are more expensive but are more effective at detecting the larger particles of smoke produced by slow burning fires such as smouldering foam-filled furniture.

Obviously cost and effectiveness of operation are key issues when promoting the installation and use of smoke alarms.

The following hierarchy of smoke alarms is set out in ascending order of cost and functionality

1. Ionisation alarm fitted with a one-year battery, which requires changing each year. This type is ideally suited for the target group that has the ability, both physical and financial, and the motivation, to change the battery.

2. Ionisation alarm fitted with a one-year battery and has a hush button. This has the same pros and cons as 1 above, but may help to eliminate the removal of the battery following nuisance alarms.

3. Optical alarm fitted with a one-year battery. The problems relating to battery replacement remain with this option. Nuisance alarms may be expected to be similar to 2.

4. Ionisation or optical alarms as in 2 and 3 above, but with the alarms fitted with lithium batteries with a ten-year life. This option is more suitable where the likelihood of battery replacement is not high, such as with elderly people, those of low socio-economic groups and those in social housing. It is important that there is awareness of the need to replace the unit at the appropriate time.

5. Mains powered smoke alarms with battery back-up. These are ideal for high-risk groups and for social housing projects for the elderly and infirm. Such alarms should be installed so as to comply with BS 7671 and the installation should only be carried out by qualified and competent electricians, i.e. members of the Electrical Contractors Association (ECA) or the National Inspection Council for Electrical Installation (NICEIC) registered persons.

6. Mains only powered smoke alarms. Such units are available but are not generally considered to be an improvement on the lithium-battery-powered alarms referred to in 4 above.

Where to fit smoke alarms

Smoke alarms are simply screwed into the ceiling and should be fitted at least 30 centimetres (12 inches) away from any wall or light fitting and as close to the centre of the room, hallway or landing ceiling as possible. (Always read the manufacturers' instructions before fitting).

If your home is on one level, for minimum protection you should fit an alarm in the hallway between the living and sleeping areas.

If your home has more than one floor, for minimum protection one alarm should be fitted at the bottom of the staircase with further alarms fitted on each stair landing.

If you choose to fit a single alarm in a home with more than one level, care should be taken to ensure that it is fitted where it can be heard throughout your home - particularly when you are asleep. Normally this would be at the top of the stairs. Although ionisation and optical alarms are equally effective, optical alarms may be preferred in this particular situation as they are especially good at detecting slow-burning or smouldering fires.

Important: The manufacturers' instructions should be followed at all times, particularly where mains powered alarms are to be installed.