Archive Website of the UK government

How many smoke alarms do you need?

The more alarms you have, the safer you'll be - as long as they are working - so make sure you test them weekly. You should have a minimum of one alarm on each floor. However, if you have only one alarm and two floors, put it somewhere you’ll be able to hear it when you're asleep.

If you have a large electrical appliance, like a computer, in any of the bedrooms, you should fit a smoke alarm there too. You should also make sure you test it weekly.

Installing your smoke alarm

Some fire and rescue services in England offer free home fire risk checks. This involves firefighters visiting your home and offering fire safety advice for you and your household. They may be able to install your smoke alarm for free.

It usually takes a few minutes to install your smoke alarm yourself - just follow the manufacturer's instructions that come with it. The best place for your smoke alarm is on the ceiling, near or at the middle of the room or hall. The alarm should be at least 30cm (one foot) away from a wall or light.

If it is difficult for you to fit your smoke alarm yourself, ask a family member or friend to help you, or contact your local fire and rescue service.

• Contact your local fire and rescue service

Choosing a smoke alarm

There are two types of smoke alarm:

Ionisation alarms

Ionisation alarms are the cheapest and most readily available smoke alarms. They are also very sensitive to 'flaming fires' - fires that burn fiercely, like chip-pan fires. Ionisation alarms will detect flaming fires before the smoke gets too thick.

Optical alarms

Optical alarms are more expensive. However, they are more effective at detecting slow-burning fires, like smouldering foam-filled furniture or overheated wiring. Optical alarms are less likely to go off accidentally and so are best for ground-floor hallways and for homes on one level.

For the best protection, you should install one of each. However, if you can’t have both, it’s still safer to have either one, rather than none at all.

British Standard Kitemark

Whichever model you choose, you should make sure that it meets British Standard 5446, Part 1 (BS 5446-1) and ideally also carries the British Standard Kitemark. Your local fire and rescue service will help you decide which is best for your circumstances if you would like some advice.

• Find your local fire and rescue service

The different models available

A lot of people forget to check their smoke alarms, so the best choice of power supply is usually the one that lasts longest.

Standard-battery alarms

An ‘ionisation battery alarm’ is the cheapest and most basic smoke alarm available. An ‘optical battery alarm’ is a little more expensive. Both run off 9-volt batteries.

Battery alarms with an emergency light

These come fitted with an emergency light which comes on when the alarm is triggered. They are particularly suitable if someone in your house has hearing difficulties and may help light up an escape route.

Alarms with ten-year batteries

These are slightly more expensive, but you save on the cost of replacing batteries. They are available as ionisation/optical alarms and are fitted with a long-life lithium battery, or a sealed power pack that lasts for ten years.

Models with a ‘hush’ or ‘silence’ button

Some models are available with a 'hush' button which will silence the alarm for a short time. This can be used when cooking, for example. If there is a real fire, giving off lots of smoke, the hush system is overridden and the alarm sounds. These models will continue to remind you they have been silenced by 'chirping' or by displaying a red light.

Mains-powered alarms

These are powered by your home’s electricity supply and need to be installed by qualified electricians. There’s no battery to check, although they are available with battery back-up in case of a power cut.

Interconnecting or linked alarms

Some alarms can be connected to each other so that when one senses smoke, all the alarms in the property sound. They are useful for people with hearing difficulties and also in larger homes.

Mains-powered alarm with strobe light and vibrating pad

These are designed for people who are deaf or have hearing difficulties. If there’s a fire, the alarm alerts you with a flashing light and vibrating pad - which is placed beneath your pillow.

Mains-powered alarm which plugs into a light socket

This type of alarm uses a rechargeable battery that charges up when the light is switched on. It lasts for ten years and can be silenced or tested by the light switch.

Maintaining your smoke alarm

To keep your smoke alarm in good working order, you should:

• test it once a week, by pressing the test button until the alarm sounds
• change the battery once a year (unless it’s a ten-year alarm)
• replace the whole unit every ten years

More useful links

• Health and safety in privately rented accommodation

Useful contacts

• Home and community contacts