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Smoke Alarm and Detectors

Smoke Alarm Advice

Every year the Fire and Rescue Service is called to over 600,000 fires which result in over 800 deaths and over 17,000 injuries.

About 50,000 (140 a day) of these are in the home and kill nearly 500 and injure over 11,000, many which could have been prevented if people had an early warning and were able to get out in time. In fact you are twice as likely to die in a house fire that has no smoke alarm than a house that does.

Buying a smoke alarm could help save your home and the lives of you and your family.

What are smoke alarms?

Smoke alarms are self contained devices that incorporate a means of detecting a fire (smoke detector) and giving a warning (alarm). They are about the size of a hand and are normally fitted to the ceiling. They can detect fires in their early stages and give you those precious minutes to enable you and your family to leave your house in safety.

What type of smoke alarms are available?

There are four types of smoke alarm currently on the market – ionisation, optical (also described as photo electronic), heat and combined. Combined Smoke and CO Detector

Ionisation: These are the cheapest and cost very little to purchase. They are very sensitive to small particles of smoke produced by fast flaming fires, such as paper and wood, and will detect this type of fire before the smoke gets too thick. They are marginally less sensitive to slow burning and smouldering fires which give off larger quantities of smoke before flaming occurs.

Optical: These are more expensive but more effective at detecting larger particles of smoke produced by slow-burning fires, such as smouldering foam-filled upholstery and overheated PVC wiring. They are marginally less sensitive to free burning flaming fires. Optical alarms can be installed near (not in) kitchens, as they are less likely than ionisation alarms to go off when toast is burned.

Heat Alarms: They detect the rise in temperature from a fire and are insensitive to smoke. They can therefore be installed in kitchens. They only cover a relatively small area of a room, so potentially several heat alarms need to be installed in a large kitchen.

Combined Smoke Alarms (Ionisation and Optical): These detectors are effective at detecting slow-burning as well as flaming fires – which are both common types of fire.

Multi-Sensor Alarms: Combinations of optical and heat alarms for suppression of false alarms

Combined Smoke and CO (Carbon Monoxide) Alarms: The Kidde 10DS (pictured) finally allows you to combine two essential alarms into one (smoke and CO). This reduces costs, reduces the maintenance required and takes up less room in your living spaces. It is also a big step forward in terms of material saving, energy saving and getting rid of radio-activity in smoke alarms.

Each type looks similar and is powered either by a battery, or mains electricity (or a combination of both). Some are inter-connectable so that any smoke detected at one point can raise the alarm at all others.

Some have additional facilities, such as emergency lights and silence buttons, for use where false alarms can be a nuisance e.g. when cooking.

In a standard smoke alarm, the battery will need to be replaced every 12 months. You can buy alarms fitted with sealed 10 year batteries. The advantage is that you don’t have to replace the battery every year.

Mains-powered alarms eliminate the problem of checking the battery. But to be really safe you need a battery back-up (which costs extra). They need to be installed by a qualified electrician. Prices start at about £15, but you need to add the cost of the fitting.

Some people find their alarms are frequently set off when they’re cooking or when the toast burns. An alarm installed inside the kitchen must be a heat alarm rather than a smoke alarm. Just outside a kitchen (eg in hall or dining room) an optical smoke alarm should be installed, as these are less sensitive to false alarm.

The alarm lets you know it’s been silenced by “chirping” or by displaying a red light – and a real fire producing lots of smoke will set it off anyway.

Alarms can also come with an additional light. When the alarm sounds, the light comes on. The light can help you see your way out, and it’s good for alerting people whose hearing isn’t perfect.

For people who are hard of hearing or deaf, there are alarms which come with a pad. When the alarm goes off, the pad vibrates, and a strobe light flashes – alerting you or waking you up instantly.

Which smoke alarm should I choose?

When deciding which type of alarm to buy you should consider which type of fire is most likely to occur in your home. Generally, both types of fire are common so the best form of protection would be to choose at least one smoke alarm of each type. Ideally, and to ensure continuity of supply, mains powered alarms with a back up power supply (e.g. battery, rechargeable capacitor) are the best option but simple battery powered alarms of either type will give good minimum protection.

We recommend that you buy your smoke alarms from Safelincs. Always buy an alarm which conforms to the British Standard. This means the alarm has achieved a standard acceptable to the British Standards Institution (BSI). Smoke alarms should carry the well-known Kite mark.

How many should I fit in my home

The number of smoke alarms to fit in your home depends on your particular circumstances. Fires can start anywhere, so the more that are fitted, the higher the level of protection.

For maximum protection an alarm should be fitted in every room (except bathroom) You should choose the type most suited to the risk in each room. For minimum protection the number to be fitted will depend on the type of home you live in:

If your home is on one floor, one smoke alarm, preferably of the optical type, may be enough to provide you with early warning of a fire.

If your home has more than one floor, at least one alarm should be fitted on each level. In this case a combination of optical and ionisation alarms, preferably interconnected, will give the best protection.

Do not fit an alarm in the bathroom, as steam may trigger the alarm. In kitchens and garages where steam or exhaust fumes can occur, install a heat alarm. Cigarette smoke will not normally set off an alarm.

Where do I fit my smoke alarms?

Smoke alarms are simply screwed into the ceilings and should be fitted as close to the centre of the room as possible, but at least 30 centimetres (12 inches) away from any wall or light fitting. You should always make sure that your alarm is fitted in a place where it can be heard throughout your home – particularly when you are asleep.

If your home is on one level, you should fit the alarm in the hallway between the living and sleeping areas. If you have only one smoke alarm and two floors, put it where you can hear it when you’re asleep – in the ceiling at the top of the stairs leading to the bedrooms. 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.

If you have a TV or other large electrical appliance in your bedroom, you should fit a smoke alarm there.

If your home has more than one floor then at least one alarm should be fitted on each level, in this case a combination of optical and ionisation alarms, interconnected, will give the best protection.
Important: The manufacturers’ instructions should be followed at all times, particularly where mains powered alarms are to be installed.

Looking after your smoke alarm

Follow the manufacturers’ instructions – smoke alarms need very little maintenance. A few minutes of your time during the year will ensure that your alarm is working and could help save your life and the lives of your family. You should:

  • Once a week test each alarm by pressing the test button till the alarm sounds
  • Once a year change the battery (unless it’s a ten-year alarm)
  • Twice a year gently vacuum the smoke alarm using the soft-brush attachment to remove dust from the sensors
  • After 10 years it’s best to get a whole new alarm.

Do you keep forgetting to check your smoke alarms, help is at hand. Let us remind you to check them here.

Where can I buy them?

We recommend you buy your smoke alarms from a reputable company such as Safelincs who are able to cater for all your fire safety needs with their extensive range of products.


Buying and fitting smoke alarms, and ensuring they are carefully and properly maintained, could give you those precious few extra minutes in which to make your escape safely.

Plan an escape from your home in advance and talk about it with your family. If a fire occurs you may have to get out in the dark and difficult conditions. Escaping will be a lot easier it everyone knows where to go. Make sure your routes remain free of any obstructions and that there are no loose floor coverings that could trip you.

Always check the battery regularly, replacing it when necessary, and never remove it for other purposes.


Downloadable fire safety leaflets in various languages can be downloaded here.

UK Fire Service Resources recommends Safelincs Safety Products for every type of smoke alarm you will ever need.