Fire detection – are you making the grade?

Effective fire detection systems help to save lives and homes. However, with regulations constantly evolving, it’s vital that builders and contractors are fully aware of fire protection guidelines and how ensure all requirements are met. Jeremy Roberts of SONA highlights the key areas for consideration.

In the case of fire safety, BS 5839 Part 6 is the code of practice for the planning, design, installation, commissioning and maintenance of fire detection in domestic premises.

BS 5839-6 provides minimum grades and categories of fire detection systems for different types of housing. Generally speaking, the greater the fire risk and the more demanding the application, the more comprehensive the system needs to be.

Grades of system

BS 5839-6 applies grades to the technology used in fire detection systems. There are six grades, A to F, with grade A being the most comprehensive.

  • Grade F: System consisting of one or more battery powered smoke alarms (and heat alarms if required)
  • Grade E: System of interlinked mains powered smoke alarms (and heat alarms if required) with no stand-by supply. The connection between the alarms can be hardwired or radio-frequency (RF)
  • Grade D: System incorporating one or more interlinked mains powered smoke alarms (and heat alarms if required), each with a stand-by supply
  • Grade C: System consisting of fire detectors and alarm sounders (potentially smoke alarms) connected to a common power supply, consisting of normal mains and stand-by supply, with central control equipment
  • Grade B: Fire detection and alarm system consisting of fire detectors (other than smoke alarms), fire alarm sounders and control and indicating equipment to either BS EN 54-2 or to Annex C of BS 5839: Pt.6
  • Grade A: Fire detection system incorporating control and indicating equipment to BS EN 54-2, and power supply to BS EN 54-4, installed to BS 5839: Pt.1

Generally, a Grade D system incorporating one or more interlinked mains powered smoke alarms (and heat alarms if required), each with a stand-by supply is the common standard for the majority of domestic fire detection system installations.

Grade E is deemed inappropriate where there could be potential interruptions to mains power (i.e. non-payment or coin-operated meters). Grade F systems (battery-only powered alarms) will only be considered for some existing, owner-occupied dwellings, but only where there is reasonable certainty that batteries will be replaced when needed. This isn’t recommended and the use of an alarm with a sealed-in battery should be the preferred option.

Categories of system

BS 5839-6 divides fire detection systems into different categories that relate the level of protection afforded by the system, as follows. The category defines which areas detectors (i.e. smoke/heat alarms) should be positioned.

  • LD1: A system installed throughout the dwelling, incorporating detectors in all spaces that form part of the escape routes from the dwelling, as well as in all rooms and areas in which fire might start (other than toilets, bathrooms and shower rooms)
  • LD2: A system incorporating detectors in all spaces that form part of the escape routes from the premises, and in all rooms or areas that present a high risk of fire to occupants
  • LD3: A system incorporating detectors in all spaces that form part of the escape routes from the dwelling

Builders and contractors should aim to install fire detection systems that fit into the LD1 category, however LD2 does offer a good level of protection and is now the standard of the majority of detection systems in domestic situations.

The LD3 category is intended to protect escape routes for those not directly involved in a fire incident and may not provide protection to an individual in the immediate vicinity of a fire.

It is also advisable to have at least one carbon monoxide alarm in any room containing a solid fuel-burning appliance.

Technological advancements

BS 5839-6 also takes into consideration advances in detector technology to help minimise false alarms. One key advancement is the use of multi-sensing smoke alarms, which combine optical sensing with thermal enhancement for detection of fast flaming and slow smouldering fires in a single alarm.

Using a multi-sensing smoke alarm not only offers builders the sensing benefits of both ionisation and optical alarm technology, but also significantly reduces the potential of nuisance alarms.

Builders and contractors have clear responsibilities to fit smoke, heat and carbon monoxide alarms that offer high levels of protection to occupants and the building, even if it is not mandatory in legislation. By following the latest guidelines, builders can be confident that they are providing fire detection systems that meet the most up-to-date standards.

Jeremy Roberts is sales director at SONA.