The LWF Blog

Fire Safety Engineering for Design – Fire Detection & Alarm Systems – Part 143

July 31, 2023 10:21 am

LWF’s Fire Safety Engineering blog series is written for Architects, building designers and others in the construction industry to highlight and promote discussion on all topics around fire engineering. In part 142, LWF discussed supervising station fire alarms and manual fire alarms. In part 143, we take a look at fire alarm systems for domestic dwellings.

The recommendations for fire detection standards within dwellings for the UK can be found in BS 5839-6 Fire detection and fire alarm systems for buildings – Code of practice for the design, installation, commissioning and maintenance of fire detection and fire alarm systems in domestic premises.

The standard is aimed at architects, designers and other professionals in the industry and not at homeowners. The recommendations contained within the standard are relatively complex and are graded into the following six categories:

Grade A –             A fire alarm system conforming to specific recommendations of BS EN 54-2 for control and indicating equipment (CIE) and BS EN 54-4 for power supply equipment, which has been designed and installed in accordance with specific sections of BS 5839-1.

Grade B –             A fire alarm system which conforms to certain specific recommendations of BS EN 54 covering fire detectors, fire alarm sounders, CIE and power supply.

Grade C –             A system comprising fire detectors and sounders, connected to a central control panel with mains power supply and battery back-up.

Grade D –             Mains powered smoke alarms with battery back-up.

Grade E –             Mains powered smoke alarms without battery back-up.

Grade F –              Battery powered smoke alarms.

Where a system that falls into grades D, E or F are installed and have more than one smoke detector, these should be interlinked within the same dwelling.

Once the relevant grade has been ascertained, a category should be established as per the categories given in BS 5839-1 (linked above). The D designation in the following pertains to domestic application. The L relates to life safety systems and the P is for property protection.

LD1 –                     A system installed throughout the dwelling, except toilets and bathrooms

LD2 –                     Installed in escape routes and areas of high fire risk, or risk to life safety is high

LD3 –                     Installed in the escape routes only (e.g. internal hallways or stairs)

PD1 –                    Installed throughout the dwelling, except toilets and bathrooms

PD2 –                    Installed in defined rooms or areas of the dwelling as required


In part 144 of LWF’s series on fire engineering, we will touch on the NFPA 72 guidance for fire alarm systems in private dwellings, as well as examining the types of fire detection systems. In the meantime, if you have any questions about this blog, or wish to discuss your own project with one of our fire engineers, please contact us.

Lawrence Webster Forrest has been working with their clients since 1986 to produce innovative and exciting building projects. If you would like further information on how LWF and fire strategies could assist you, please contact the LWF office on 0800 410 1130.

While care has been taken to ensure that information contained in LWF’s publications is true and correct at the time of publication, changes in circumstances after the time of publication may impact on the accuracy of this information.

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