To test a home smoke alarm, press and hold the test button until the alarm sounds, and do this at least once a month. Commercial fire alarm systems are tested differently. The premises runs a weekly test from a manual call point. A competent person functionally tests the detectors during BS 5839-1 servicing, using approved test equipment that puts smoke, or a smoke-simulating aerosol, into each detector's sensing chamber.
This guide explains how to test smoke alarms in homes and rented property, how smoke detectors in commercial fire alarm systems are tested, and which test equipment engineers use.
How to test a smoke alarm at home
Domestic smoke alarms and heat alarms have a built-in test button. Government Fire Kills advice is to test every alarm at least monthly, whatever type it is.
- Press and hold the test button until the alarm sounds.
- If it doesn't sound, replace the battery. If it still doesn't sound, replace the alarm.
- If your alarms are interlinked, follow the manufacturer's instructions to check that the other alarms respond.
- Repeat every month for every smoke alarm and heat alarm in the home.
Looking after home smoke alarms
- Change one-year batteries every year, or choose a ten-year sealed battery alarm.
- Replace ten-year alarms as a whole unit every ten years. They may need replacing sooner, depending on how often they are triggered.
- If an alarm starts to chirp regularly, replace the battery straight away. See why is my fire alarm beeping? for other causes.
- Vacuum smoke alarms every six months to remove dust.
- Fit at least one smoke alarm on every level of the home. Keep smoke alarms away from kitchens and bathrooms, where cooking or steam can set them off. A heat alarm can be used in the kitchen instead.
Browse our smoke and heat alarms for domestic and small-premises alarms.
Landlords in England
Under the Smoke and Carbon Monoxide Alarm (England) Regulations 2015, as amended in 2022, landlords must fit at least one smoke alarm on each storey that has living accommodation. For a new tenancy, they must check that each required alarm is working on the day the tenancy begins.
How to test smoke detectors in a commercial fire alarm system
Commercial fire detection and alarm systems are designed, installed and maintained under BS 5839-1, the code of practice for non-domestic premises. The current edition is BS 5839-1:2025. Testing is shared between the premises and a competent servicing organisation.
Weekly test: operate a manual call point
Each week, during normal working hours, the premises should set off the system from a manual call point, using a different call point each time so every one is tested in turn. Many fire and rescue service log books recommend testing at about the same time each week, so occupants know it is a test. During the test:
- Check that the sounders and visual alarms work and that connected door releases operate.
- If the system is monitored by an alarm receiving centre, contact the centre immediately before and after the test.
- Record the date, time, call point used and result in the fire alarm log book.
Call points are usually tested with the manufacturer's test key. We stock manual call points and call point test keys.
Servicing: about every six months, by a competent person
BS 5839-1:2025 recommends inspection and servicing visits at intervals of about six months, carried out by a competent person. A visit between five and seven months after the previous one is acceptable.
Functional testing of detectors
Servicing includes functional testing of automatic detectors, and the service regime should cover every detector over each year. The key requirements are:
- Smoke detectors should be tested with a method that shows smoke can actually enter the sensing chamber, such as a smoke generator or a suitable aerosol. Magnet tests and self-monitoring do not count as a functional test.
- Heat detectors should be tested with a suitable heat source, not a live flame.
- Multi-sensor detectors: where the system design allows, the 2025 edition recommends testing the individual sensors together.
- Test materials must not damage the detector or affect how it performs later. Follow the detector manufacturer's guidance on suitable test materials.
Smoke detector test equipment
Engineers use purpose-made detector testers on access poles, so they can test ceiling detectors from the floor. The main options are:
- Aerosol dispensers: a cup such as the Solo 330 holds a can of smoke test aerosol (for example Solo A10S) over the detector.
- Electronic smoke testers: the Solo 365 produces test smoke from a replaceable cartridge instead of an aerosol.
- All-in-one testers: Testifire and Testifire XTR2 heads produce smoke and heat stimuli in one unit, and some Testifire models also produce CO. They suit sites with multi-sensor detectors.
- Heat detector testers: cordless and mains-powered heaters such as the Solo 461. See heat detector testers.
- Accessories: telescopic access poles, detector removal tools, CO test gas and carry bags.
Browse our wider test and service equipment range. We supply genuine, brand-new, factory-sealed products with fast, tracked UK delivery.
Keep a record of every test
Record weekly tests, service visits, faults and false alarms in the fire alarm log book. Fire and rescue service log book templates include sections for these records, and they help your servicing organisation spot recurring problems. Our weekly fire alarm testing and log book guide covers this in more detail.
Frequently asked questions
How often should smoke detectors be tested?
Test home smoke alarms at least monthly with the test button. In commercial systems, run a call point test weekly and have a competent person service the system about every six months, with every detector functionally tested over the year.
How do you test a smoke alarm without smoke?
For a domestic alarm, press and hold the test button until it sounds. Commercial detectors need a functional test that gets smoke, or an approved smoke-simulating aerosol, into the chamber.
Is pressing the test button or using a magnet enough for commercial detectors?
No. Under BS 5839-1, magnet tests and self-monitoring are not a functional test. The test must show that smoke can reach the sensing chamber.
How do you test a fire alarm system?
Operate a different manual call point each week, check that the alarm sounds throughout the building, and record the result in the log book. Detector testing is part of the six-monthly service by a competent person.
Who can service a commercial fire alarm?
A competent person or organisation. Many premises use a servicing company with third-party certification, such as BAFE SP203 or LPS 1014.
This guide is general information; follow your fire risk assessment and a competent person's advice.