TECHNICAL UPDATE FEATURES
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Government consultation on fire safety. It introduces requirements for all homes in Scotland to have satisfactory provision for detecting and warning of fire to ensure they are safe for occupants. This comes into effect from 1 February 2021. The Housing (Scotland) Act 2006
(Modification of the Repairing Standard) Regulations 2019 were amended due to the above extension to the tolerable standard. The modification of the repairing standard removes an existing requirement for “satisfactory provision for detecting and warning of fire” from this standard which only applied to private rented housing. After 1 February 2021, the requirement for satisfactory provision for detecting and warning of fire will be in the tolerable standard which applies to all housing.
What you need to know BS 5839-6:2019 now provides recommendations for fire detection and alarm systems in new and existing supported housing, self-catering premises and premises with short-term paying guests, such as holiday flats and B&Bs. This is in addition to existing recommendations and guidance for systems in new and existing domestic premises and sheltered housing. Updating references to other standards has also been a part of the revision, and BS 5839-1:2017 is now included. This is a particularly relevant standard if designing a fire detection and fire alarm system for larger domestic premises (with a floor area greater than 200m2).
The recommendations within that standard apply where a Grade A system has been specified – this is the grade recommended in BS 5839-6:2019 which is deemed to be suitable for that size of premises. Following the tragic events at Grenfell
Tower, there is new guidance included for communal fire detection systems. It explains that fire detection and fire alarm systems are commonly provided in blocks of flats for the purpose of operating smoke control systems and, if designing such systems, BS 7273-6 is the appropriate standard. The guidance advises that as a consequence of cladding on blocks of flats being found to be non-compliant with the requirements of the building regulations, fire detection and fire alarm systems are being installed in communal areas of some high-rise residential buildings. However, it is stressed that such systems are only intended as a temporary measure pending removal of the cladding and these systems are outside the scope of BS 5839-6:2019. Compartmentation between occupancies is normally sufficient to ensure that a fire is contained in the dwelling of origin and will allow other occupants to remain safely in their own flats. BS 5839-6 therefore does not provide any recommendations for fire detection systems in the communal areas of blocks of flats as the ‘Stay put’ policy is deemed to provide sufficient protection. The guidance, however, goes on to
state that where such communal fire detection systems can be justified or are requested, the recommendations
WHAT THE REVISED GRADES MEAN
●●Grade A: Separate detectors, sounders and central control and indicating equipment with back-up power supply that conforms to British Standards BS EN 54-4 ●●Grade C: A system of fire detectors and alarm sounders that are mains powered with back-up power supply and central control equipment ●●Grade D1: A system of one or more mains-powered detectors, each with an integral standby supply consisting of a tamper-proof battery or batteries
22 CABLEtalk AUGUST/SEPTEMBER 2019
●●Grade D2: A system of one or more mains-powered detectors, each with an integral standby supply consisting of a user-replaceable battery or batteries ●●Grade F1: A system of one or more battery-powered detectors powered by a tamper-proof primary battery or batteries ●●Grade F2: A system of one or more battery-powered detectors powered by a user-replaceable primary battery or batteries
ABOVE: All alarms should be ceiling mounted
in BS 9991 and BS 5839-1:2017 can be followed (BS 9991 provides guidance on evacuation strategies and associated detection and warning systems for purpose-built blocks of flats).
Revised grades of system Probably the most significant change in BS 5839-6:2019 is associated with the revision of the defined grades of systems, which are given for the purposes of specifying fire detection and fire alarm systems and their associated engineering parameters. Grade B and E systems are no longer defined systems, mainly because they were not in common use, while Grade D and Grade F are each now split into two sub-grades. This means that a Grade D system can now be either a Grade D1 or a Grade D2. Likewise, Grade F systems can now either be a Grade F1 or a Grade F2.
When deciding upon a suitable grade and category of system, the designer should always ensure that the level of protection provided is related to the nature of the premises, the level of fire risk and the characteristics of the likely occupants of the premises – a higher fire risk will require a high reliability of system. The recommendations provided in the amended Table 1 in BS 5839-6 help simplify selection of an appropriate grade and category of system for typical
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