Smoke Alarms

Smoke Alarms

Working smoke alarms are a vital protection from the dangers of fire in the home. They provide the 
early warning and precious time which can save lives and prevent injury.
The smoke alarm message, and in many cases, the installation of smoke alarms themselves, 
are among the most important community fire safety priorities for brigades.
The aim of having working smoke alarms in every home is also a high government priority.
In May 2000, a ministerial initiative resulted in the formation of a joint fire and insurance 
industry/Home Office working group to take forward the strategy for achieving this 
widespread ownership and protection. The National Community Fire Safety Centre (NCFSC) 
Fire Action Plan campaign in September 2000 is part of along-term initiative which will heighten 
awareness of the importance of smoke alarms, bringing  together campaigns 
and information, industry support, research, and the practical experience and expertise of fire 
services working in the community.

The types of smoke alarm

here 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. Further information is available 
in BS 5839 : Part 6, paragraphs 5.1 and 5.2.
Purchase and do-it-yourself installation of battery-powered alarms by members of the public are heavily 
dependent upon the quality of the instructions provided with the units.
As part of the work following the ministerial smoke alarm initiative, the NCFSC will be revising the Home
Office smoke alarm leaflet (Wake up! Get a smoke alarm) to ensure that the information is presented as
clearly as possible.

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.