Make sure you’ve got the right support
In this article, our Associate Member takes us through considerations for contractors when designing, installing, commissioning and maintaining domestic fire detection and fire alarm systems
Since February 2022, following an extension to the Tolerable Standard by the Housing (Scotland) Act 1987 (Tolerable Standard) (Extension of Criteria) Order 2019, all homes in Scotland, regardless of tenure, are required to have:
One smoke alarm in every circulation space on each storey, e.g. halls, landings, etc
One smoke alarm in the room most used during the daytime
One heat alarm in the kitchen
All alarms interlinked, either through a wired or wireless system
Alarms to be mains-powered or have a tamper-proof lifetime battery
All alarms ceiling mounted, unless indicated as suitable for wall mounting by the manufacturer
All alarms regularly maintained and tested.
British standards are not legislation and compliance with a British standard does not provide legal immunity. Nonetheless, for any competent person, adhering to the most recent standard is unquestionably the best defence in any legal proceeding.
It is common for organisations to refer to compliance with BS 5839-6: The Code of Practice for the design, installation, commissioning, and maintenance of domestic fire detection and fire alarm systems in domestic premises.
Its current version was published in 2019 and was subject to an amendment in 2020. BS 5839-6 is recognised as providing guidance and recommendations to support those implementing fire precautions, such as architects, enforcing authorities, installers and designers. It should not be cited as a specification; claims of compliance should be accurate and any deviations from the standard should be justified.
Design
Table 1 of BS 5839-6 recommends minimum grades and categories of fire detection and fire alarm systems in typical premises.
While the Tolerable Standard permits battery-powered detectors via a tamper-proof battery, i.e. Grade F1 system as per BS 5839-6, this would not meet the minimum recommendations of Table 1 for all classes of premises.
For example, a minimum of a Grade D1, Category LD2 system is recommended for any rented, existing, new, or materially altered single-family dwelling, where no floor exceeds 200m2 and the dwelling is no more than three storeys:
Grade D1: A system of one or more mains-powered detectors with an integral standby supply consisting of a tamper-proof battery or batteries.
Category LD2 system: Includes detectors in high-risk areas, such as any kitchen and principal habitable room, along with circulation spaces that form part of escape routes, e.g. hallways and landings. Furthermore, the standard takes account of the increasing amount of electrical equipment installed within the loft space, such as solar photovoltaic (PV) inverters or boilers.
The mix of electrical equipment in a location, which may include exposed timber, felt roof covers and storage of combustible materials such as cardboard boxes, increases the risk of fire.
Designers are advised, as per Clause 11.1, that where this is the case, any Category LD2 system needs to incorporate a detector within the loft.
Recognising there is a risk of unwanted alarms due to dirt or dust, Clause 11.2 also recommends the use of an ionisation chamber smoke detector or a multi-sensor detector with compensation for drift.
Installation
Clause 15.4 recommends all Grade D power supplies to be connected to an independent circuit or connected to a local lighting circuit. However, the recommendations for labelling within the clause can be overlooked. The examples above show the different recommendations for labelling based on the power supply.
Clause 16.4 recommends that “conductors used for interconnection of smoke or heat alarms should be readily distinguishable from those supplying power, e.g. by colour coding”. However, it is still common to find the interlinking conductor covered with sleeving or insulation tape. To avoid confusion, any interlinking conductors that operate at extra-low voltage should be readily identifiable from those operating at low voltage.
Commissioning
Clause 23.3 recommends a design, installation and commissioning certificate to be issued following the completion of a fire detection and fire alarm system.
Annex E contains a model form for Grade C, D and F systems. The certificate has a section where any variations from the standard should be recorded.
A variation is defined as an “intentional departure from a specific recommendation of BS 5839”. A common variation is where certain tests are performed in accordance with manufacturer instructions as opposed to the recommendations of Clause 23.3, e.g. pushing the test button as opposed to undertaking a smoke or heat test. It is important to note that a variation is not intended to account for errors in design, installation or commissioning and may need the prior agreement of third parties, such as those charged with fire safety enforcement.
Maintenance
Clause 25.2 recognises that in Grade C and D systems, manual test switches can be installed to aid accessibility when undertaking routine testing.
Detectors installed in loft spaces or on high ceilings make access problematic for those testing the fire detection and fire alarm systems. Therefore, as a competent designer, consideration for those undertaking the maintenance and regular testing of the system is essential. Table 3 of BS 5839-6 offers recommendations on testing and battery replacement, and for Grade D systems, this includes:
The user carrying out a monthly test by pushing the test button
Internal batteries should be replaced in line with manufacturer requirements or at low battery levels, whichever is earliest.
CORGI Technical Services has been synonymous with safety for more than 50 years. Offering a range of safety services and expertise including auditing, consultancy and training, it works with housing associations, local authorities and facilities management companies, with extensive experience of electrical auditing across thousands of properties. Find out more at www.corgitechnical.com
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