Optical Smoke Alarms

Optical smoke alarms are not recommended for use in a kitchen area as they are likely to false alarm from cooking fumes and steam. A heat alarm is the best alarm to install in a kitchen area as it detects a rapid rise in temperature rather than 'smoke' particles, meaning it will not false alarm from normal cooking activities.

An optical smoke alarm is superior to ionisation models because it responds faster to smouldering fires that produce large smoke particles, while being less prone to false alarms from cooking.

Optical smoke alarms work best in bedrooms, living rooms, and hallways where smouldering fires are most likely, positioned centrally on ceilings away from air vents and windows.

Optical smoke detectors can experience reduced sensitivity in very dusty conditions, so regular cleaning and maintenance are important to ensure proper operation in challenging environments.

Testing optical smoke alarms monthly by pressing the test button is recommended to ensure proper operation, with additional checks using smoke detector test aerosols annually.

To ensure your smoke alarm is functioning properly, it's essential to test it regularly.

Steps to Test a Smoke Alarm

1. Check the Date: Ensure the smoke alarm is not older than 10 years. If it is, replace it.
2. Press the Test Button: Locate the test button on the smoke alarm. Press and hold it for a few seconds. You should hear a loud alarm sound, indicating that the unit is working. DO NOT USE REAL FIRE, VAPES, OR CIGARETTES TO TEST SMOKE ALARMS. This can damage the smoke alarm and void any warranty. For more detailed guidance, please consult the manual provided with your smoke alarm.
3. Clean the Alarm: Dust and debris can affect the alarm's performance. Use a vacuum cleaner with a soft brush attachment to clean the outside and inside of the alarm.
4. Document the Test: Keep a record of when you tested the alarm and any maintenance performed. This helps ensure regular checks.

Frequency of Testing

• Monthly: Test the smoke alarm every month.
• Annually: Clean your alarm. If your alarm is sounding a low battery warning, replace the batteries.
• Every 10 Years: Replace the entire smoke alarm unit.

Regular testing and maintenance of your smoke alarm can significantly enhance your safety and preparedness in case of a fire.

Sign up to our free smoke alarm reminder service to receive regular reminders by email or text message.

Optical smoke alarms, also known as photoelectric detectors, have a high sensitivity to large particles in the air. They are slightly quicker at detecting slow-smouldering fires that produce a lot of smoke (such as fire from soft furnishings). They are suitable for living rooms and sleeping areas and are used near kitchens as they are less prone to false alarms.

Ionisation smoke alarms use a small amount of radioactive material in the sensor chamber to detect fires, and have been discontinued. Safelincs encourages customers to purchase optical smoke alarms instead.

See also heat alarms for the most suitable protection in a kitchen.

Read more about how different smoke alarms work.

Yes, air purifiers may cause ionisation smoke alarms to sound falsely. To prevent this from happening, position the air purifier as far away from smoke alarms as possible.

Please note: Ionisation smoke alarms contain a small amount of radioactivity and as such they are being phased out in the UK. It is recommended that you replace your ionisation smoke alarms with an optical smoke alarm.

We recommend installing an optical smoke alarm in a bedroom with an en suite bathroom.

It would be less likely to sound a false alarm if steam or water droplets were to come into contact with the smoke alarm. They are also slightly quicker at detecting slow smouldering fires that can originate from upholstery and over-heated wiring. 

Detectors should usually be installed as central to the room as possible. However, we recommend ensuring your detector is not installed directly in the path of the bathroom door as smoke alarms are not designed for use in bathroom areas.

For most rooms including bedrooms, living rooms, downstairs hallways and even the loft space we recommend using optical smoke alarms. They are designed to quickly detect smoke from all sources and are particularly quick to detect smouldering fires, as well as being less prone to false alarms caused by steam and fumes created by everyday cooking and fireplaces under normal, safe circumstances.

Previously, ionisation smoke alarms were recommended for some rooms, but this older technology utilising radioactive material has been phased out of production globally in favour of optical detection.

For kitchens and garages, we recommend using heat alarms as they detect heat and not smoke, making them ideal for rooms where smoke fumes, vapours, dust, and damp are common.

We recommend using an optical smoke alarm in hallways, living rooms, dining rooms and bedrooms, as they are good at detecting smouldering fires from soft furnishings and are less likely to be set off by cooking fumes from a connected kitchen.

Heat alarms are recommended for kitchens and garages as they do not sound false alarms from cooking fumes, vehicle fumes or steam.

Ionisation alarms have been phased out due to the small amount of radioactive material used in the detector chamber. Safelincs recommends optical smoke alarms where ionisation alarms were previously used.