What is BS 5839-6?

Glossary · Alarms, lighting and home installs

How BS 5839-6 works

BS 5839-6 is the part of the British Standard for fire detection and alarm systems that deals with homes. Aico’s summary of the 2019 edition says it covers all domestic premises, new-build and existing.^{[1]Aico, Fire British Standard BS 5839-6:2019+A1:2020} The full standard is paid for and long. This page uses the government’s and the manufacturer’s published summaries.

The standard uses two labels together. A Grade describes the system: how the alarms are powered and linked. A Category, written LD1, LD2 or LD3, describes how much of the home the alarms cover. The standard says the level of protection should relate to the fire risk, and that the higher the Category, the higher the protection.^{[1]Aico, Fire British Standard BS 5839-6:2019+A1:2020}

The 2019 edition changed the grades. Aico lists Grade C as redefined, Grade D replaced by D1 and D2, and Grade F replaced by F1 and F2.^{[1]Aico, Fire British Standard BS 5839-6:2019+A1:2020} Grades D1 and D2 are the ones set out in the summary for houses.

Grades and Categories

All the Category descriptions and the Grade D definitions are from Aico’s summary.^{[1]Aico, Fire British Standard BS 5839-6:2019+A1:2020} Across all Categories, alarms should not be installed in toilets, bathrooms or shower rooms.^{[1]Aico, Fire British Standard BS 5839-6:2019+A1:2020}

Aico’s summary pairs these labels with property types. For rented homes, new or existing, it shows Grade D1 with Category LD2. It adds that heat alarms should be in every kitchen and a smoke alarm in the principal habitable room.^{[1]Aico, Fire British Standard BS 5839-6:2019+A1:2020} For a new owner-occupied house of two or three storeys it shows Grade D2 with Category LD2, with the same kitchen and habitable room note.^{[1]Aico, Fire British Standard BS 5839-6:2019+A1:2020}

What the law asks for

Building Regulations are lower than the standard’s table. The government’s Approved Document B guidance says all new dwellinghouses should have smoke alarms to at least Grade D2 Category LD3. Its FAQ notes that the standard’s own table recommends Grade D1 Category LD2, but says a Grade D2 Category LD3 system is adequate for Part B.^{[2]GOV.UK, Approved Document B: Fire safety - frequently asked questions}

For rented homes in England, the landlord rules do not set the type of alarm. The government guidance recommends alarms that meet BS 5839-6, with sealed-for-life batteries rather than replaceable ones where battery alarms are chosen. The legal minimum is at least one smoke alarm on each storey used as living accommodation.^{[3]Department for Levelling Up, Housing and Communities, Smoke and Carbon Monoxide Alarm (Amendment) Regulations 2022: guidance for landlords and tenants} Our smoke alarm positions page covers placement.

Mains-powered alarms need to be installed by a qualified electrician.^{[5]Home Office, Fire safety in the home} That work is covered by our smoke alarm and fire safety service, which fits mains-wired, interlinked alarms and certifies the job.

Example

Hannah owns a three-bedroom house in Horsforth and lets it out. Her letting agent says the alarms should meet BS 5839-6. She reads the government guidance and finds the law needs at least one smoke alarm per storey used as living accommodation, but recommends alarms to the standard.^{[3]Department for Levelling Up, Housing and Communities, Smoke and Carbon Monoxide Alarm (Amendment) Regulations 2022: guidance for landlords and tenants}

Aico’s table shows Grade D1 Category LD2 for a rented home: mains-powered alarms with tamper-proof standby batteries in the hall, landing, living room and kitchen, with a heat alarm in the kitchen.^{[1]Aico, Fire British Standard BS 5839-6:2019+A1:2020} Hannah books an electrician to fit and certify a system to that specification. The wiring and alarms are separate from her EICR, which does not normally inspect fire alarm systems.^{[4]IET, EICR myths (Wiring Matters)}

What people get wrong

Many people treat BS 5839-6 as a single set of rules everyone must follow. It is a code of practice with several Grades and Categories, and the minimum for Building Regulations, the recommended level for a rented house and the full protection of LD1 are three different things.

Another common belief is that a clean EICR means the alarms are checked. The IET says inspection of fire alarm systems does not generally form part of an EICR. The power supply and wiring may be included, but the alarm system is inspected to BS 5839.^{[4]IET, EICR myths (Wiring Matters)}

The bottom line

BS 5839-6 sets how a home’s fire alarms should be powered and where they should be. Grade D1 and D2 describe mains-powered systems with different backup batteries, and LD1, LD2 and LD3 describe how much of the home is covered. New homes need at least Grade D2 LD3 for Building Regulations, and the standard recommends more. If you are unsure what your home has, a registered electrician can survey it and fit a system to the grade you choose.