Housing

Smoke Alarms

Smoke detectors within the home

It is now 10 years since the government's first fire safety campaign was started, encouraging us to install smoke alarms. Roughly speaking the fatality rate in home fires where there is no working smoke alarm is twice that of homes where an alarm is fitted and working correctly.

What is a smoke alarm?

It is a self-contained device that incorporates a means of detecting a fire and warns you about it. This could be a loud high-pitched sound or light with additions of sensors for the hard of hearing.

It is now a condition of the your local Building Control that if you are having certain building works done within your home (e.g. loft conversion) you will need to install an integrated mains powered smoke alarm. (Building Regulations part B - In new homes this has been law since 1992).

Battery versions are very good but can be a nuisance as batteries run down and we find the 'I will get round to it' statement arises when it comes to renewing the battery.

We all know the familiar scenario, someone is in the kitchen cooking, the cooking sets off the smoke alarm; we can not stop it, so the battery is taken out. Is it replaced? Not always.

Different types

Ionisation: (General locations but not kitchens) These are the most popular. This is probably due to the fact they are the cheapest. They are very sensitive to small particles of smoke produced by flaming fires, such as chip pans, and will detect this type of fire before the smoke gets too thick. Hence 'going off' when cooking in the kitchen. They are marginally less sensitive to slow burning and smoldering fires, which give off larger quantities of smoke before flaming occurs
Optical: (living areas) These respond to smoldering fires and smoke given off by foam filled furnishings of overheating PVC wiring. They are less prone to nuisance alarms caused by cooking in an adjacent area
Heat: (kitchens) Less vulnerable to dust and insect contamination. To be placed in the kitchen where some 40% of home fires start. They are activated by an ambient temperature of 58°C and are not likely to be affected by cooking. They are not sensitive to smoke but in a closed room with a vigorous fire will tend to respond faster than a smoke alarm in the hallway
Carbon monoxide: (near any gas burning appliance) Not technically classified as a smoke alarm but these devices are similar in size and detect the poisonous, odourless, tasteless and colourless gas associated with the incorrect burning of household gas in fires, boilers or cookers

Smoke alarms for the deaf and hard of hearing

These have several parts. These use vibrating pads and flashing strobe lights to make the occupant aware smoke has been detected.

Typically the alarm comprises of these various parts.

The standard detector to give off a high-pitched noise when smoke has been detected
A control box
A vibrating pad placed under a pillow or mattress
A flashing strobe light that invariably built into the control box
Connecting wires

Lights and detectors can be added thus giving a wider fire detection area within the home. Most are powered by mains electricity with a back-up battery for power failure.

Fitting the control box

This would normally be sited close to a bed, fixed to a wall or flat surface e.g. bedside table. Usually hard-wire linked but technology is changing and there are limited systems that are radio-linked.

The vibrating pad and strobe

Research has shown that this is the most effective way to wake a deaf person from sleep; the best place to put the pad is under the mattress or pillow.

Fitting the detector

Smoke detectors should be located in a flat position (ceiling). This will give quickest possible warning of a fire. A detector should not be fitted less than 300mm (12 inches) away from a light fitting and as close to the centre of a room as possible.

The number of detectors fitted depends on the size of your home but obviously fires can start anywhere so the more the better. Always fit according to the manufacturers instructions.

For minimum protection

If you live on 1 level, fit a detector between the living and sleeping areas
If you live on more than 1 level, fit a detector at the bottom of the stairs and every staircase or landing to each floor
As mentioned earlier do not fit ordinary smoke alarms in kitchens or bathrooms. Similarly if you have garage do not fit one in it as the car exhaust fumes may set if off
Always fit detectors on ceilings and not shelves as smoke rises straight and would set off an alarm more quickly on the ceiling

For the smoker

Detectors do not normally respond to cigarette smoke but cigarettes do cause fires and fires set off smoke detectors.

Testing the detectors

All devices have a clearly marked test button. Depressing it once activates the detector, which advises of a potential fire risk albeit a strobe light or a high pitched sound.

A rule of thumb suggests testing once a week but the manufacturers recommendations need to be followed. Once a year the standard battery should be changed and every 6 months the alarm should be vacuum cleaned.

There are now alarms that have 'hush' buttons. This allows the alarm to be temporarily silenced from nuisance activation caused through cooking or bathroom steam. This will desensitise the alarm for approximately 15 minutes. In the event of a real fire the hush system would be overridden and the alarm would sound.

If an alarm starts to 'bleep' on a regular basis it means the battery is low and the battery should be replace as soon as possible. If this happens with a 10 year alarm then the whole unit needs to be replaced.

Costs

Depending on the detector and the size of a complete system, it is hard to put a cost to a standard system. Typically a battery-powered ionisation type costs little over £5. A mains powered system can cost over £150 plus fitting. Whatever you choose, it is money well spent.

Mains powered

These are the best type as mentioned above. There are now detectors that plug into the light socket. These have a light fitting connector and incorporate a charger. This allows the alarm to operate when the light is off but the light must be on sufficiently to recharge the battery.