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Kidde2SFW

Smoke alarm
Mains only
Optical smoke alarm

£32.41View retailers

Test score

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£32.41Amazon Marketplace UK

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The Kidde 2SFW mains-powered optical smoke alarm can be fitted as a standalone alarm or used as part of a wireless network of alarms. This means that it will be suitable for homes in Scotland after the alarms law changes there in 2022. There are two buttons, one to test it – we recommend you do this weekly – and a 'hush' button to silence it after sounding. A 9V battery will provide back-up power if there’s a power cut. And it comes with a warranty from the manufacturer covering its six-year lifetime. But what’s it like at detecting smoke and sounding the alarm? We tested it to find out. Read on to learn about how this Kidde mains-powered smoke alarm fared in our tough lab tests.

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KEY TEST RESULTS
Wood fires
Cotton fires
Sound output

Dec 2021Last checked by Which?
May 2019First reviewed by Which?
Jun 2018Released

The overall Which? test score is made up of the following star ratings, all determined by our rigorous lab tests.

How we test smoke alarms and heat alarms

27 Feb 2024

Wood fires

How we test wood fires

We measure the amount and thickness of wood smoke from a smouldering fire that is required to trigger the alarm. This test isn't carried out for heat alarms, which are tested to a different programme. Only applicable to smoke alarms.

Cotton fires

How we test cotton fires

We measure the amount and thickness of cotton smoke from a smouldering fire that is required to trigger the alarm. This test isn't carried out for heat alarms, which are tested to a different programme. Only applicable to smoke alarms.

Plastics fires

How we test plastics fires

We measure the amount and thickness of smoke from a plastics fire that is required to trigger the alarm. This test isn't carried out for heat alarms, which are tested to a different programme. Only applicable to smoke alarms.

Solvent fires

How we test solvent fires

We measure the amount and thickness of smoke from a solvents fire that's required to trigger the alarm. This test isn't carried out for heat alarms, which are tested to a different programme. Only applicable to smoke alarms.

Sound output

How we test sound output

Sound output is based on decibel levels, measured in a fully soundproofed chamber. Three stars or above are louder than 85dB – the equivalent of a lawn mower. Ones rated two stars or below should probably be avoided by those with poor hearing. This test isn't carried out for heat alarms, which are tested to a different programme. Only applicable to smoke alarms.

Sensitivity

How we test sensitivity

We test alarms with smoke from burning toast and steam from a shower head to see if they can tell the difference between normal household activity and a real fire. This test isn't carried out for heat alarms, which are tested to a different programme. Only applicable to smoke alarms.

Ease of use

How we test ease of use

Ease of use includes clarity of instructions including installation and maintenance, how simple it is to insert and replace the battery, use the hush button and any interconnectivity features. This test isn't carried out for heat alarms, which are tested to a different programme. Only applicable to smoke alarms.

General
Type	Smoke alarm
Power source	Mains only
Technology	Optical smoke alarm
10-year battery	No
Wood fire response time (Smoke alarms only)
Cotton fire response time (Smoke alarms only)
Plastics fire response time (Smoke alarms only)
Solvent fire response time (Smoke alarms only)

Features
Light	No
Hush button	Yes

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Kidde2SFW

Lowest available price

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pros

cons

How we test smoke alarms and heat alarms

Wood fires

Cotton fires

Plastics fires

Solvent fires

Sound output

Sensitivity

Ease of use

Compare retailers

How this product's score compares with other smoke alarms we've tested

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Kidde

Nest

FireAngel

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