Smoke Alarms – The Basics

Smoke Alarms are by far the cheapest and easiest way to protect you and your property from the potentially fatal side effects of a fire.  Installed correctly and in working order, they provide an early warning of a possible fire at your home or place of work, and importantly give you extra time to escape if there is a fire.

There are two main types of smoke alarm:

  • Ionisation Smoke Alarms – These are the smoke alarms found in most residential properties.  They are inexpensive to purchase, can be found in most hardware stores and are typically battery operated, although can be mains-operated too.  Ionisation Smoke Alarms are sensitive to fast flaming fires, and are ideal for detecting fires started from chip pans and will detect fires before the smoke gets too thick.
  • Optical Smoke Alarms (also known as Photoelectric Smoke Alarms) – 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.

Ionisation and Optical Smoke Alarms come in many variations:

  • Battery Operated – some come with 10-year batteries. Whilst slightly more expensive, they do save you the battery replacement costs.
  • Mains-Powered – some can be plugged into your electricity and need to be installed by qualified electricians.
  • “Silence” Button – some smoke alarms have a button that can pressed to silence the alarm for a short time; this is particularly useful when cooking and is overridden in the event of a fire.
  • Interconnected Alarms – some alarms can be connected so that when one alarm goes off, all the alarms in the property are triggered.  This is useful for larger properties or people who are hard of hearing.
  • Emergency Lights/Strobe Lights/Vibrating Pads – some smoke alarms are fitted with an emergency light, flashing strobe lighting or vibrating pads which are set off when the alarm is triggered; these all very useful for the hard of hearing.

Which Smoke Alarm is the best for you?

As each type of smoke alarm is better at detecting a fire ignited from a different source, it is highly recommended that you install at least one of each at your premises for the best protection.

Ionisation Smoke Alarms are best placed near kitchens, whereas Optical Smoke Alarms are recommended for hallways and are particularly good for flats and bungalows.

How many Smoke Alarms do you need?

That really depends on the size of your property, how many floors there are and you should also give consideration to the amount of electrical equipment you have on the premises.

Obviously, the more smoke alarms you have, the safer you’ll be.  For maximum protection against fires, you should fit a smoke alarm in every room except for the kitchen, bathroom and garage, as smoke alarms can be easily triggered by cooking fumes, steam or exhaust fumes.

If possible, you should have an alarm on every floor and in places where is can be easily heard should a fire break out in the night when people are sleeping, or when doors are closed.

Make sure your Smoke Alarm works – 1 in 3 doesn’t!

Once you have correctly fitted your Smoke Alarm following the manufacturer’s instructions, you must test it regularly to check it is functioning properly.  It is recommended that you:

  • test your Smoke Alarm once a week by pressing the test button until the alarm sounds
  • change the battery once a year, unless of course it’s a ten-year alarm
  • replace the whole unit every ten years

You should always choose a Smoke Alarm that complies with the British Standard (BS) 5446 part 1 and carries the British Standard Kitemark or PCB ‘Horseshoe’ mark.


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