Fire alarm case study · Dartford, Kent
Grade D Mains Radio-Linked Smoke and Heat Alarm System for a Six-Bedroom HMO
We installed a mains-powered, radio-linked Grade D smoke and heat alarm system for a six-bedroom HMO in Dartford, with battery backup and certification for the completed work.
- Location: Dartford, Kent
- Property: Six-bedroom HMO
- System: Grade D, mains-powered and radio-linked
- Standard: BS 5839-6
The compliance challenge: upgrading from LD3 to LD2 coverage
The project involved upgrading the fire detection layout in a recently renovated six-bedroom House in Multiple Occupation (HMO) in Dartford. The existing arrangement was identified in the project brief as providing LD3 coverage, primarily along the circulation and escape routes.
The agreed scope was to provide an LD2 system layout in line with BS 5839-6 and the property's HMO licensing requirements. This called for additional detection in the identified higher-risk areas, including the individual bedrooms, together with a heat alarm in the communal kitchen, with the alarms interlinked throughout the property.
Installer notes: flat-roof access and concealed cable routing
The flat roof prevented access to a conventional open loft, making new cable routes more challenging. To preserve the landlord's recent renovation, we spent additional time carefully fishing the 230V mains cables through concealed ceiling routes behind the plasterboard, avoiding visible surface mini-trunking wherever the available routes allowed.
The alarms use radio-linked RF interconnection alongside their local mains supplies. This links the Grade D units across the bedrooms and shared areas without requiring separate physical interconnect cables to be run through the structural walls. When one linked alarm operates, the other interlinked alarms sound as part of the system.
System specification and installation scope
The completed installation included:
- Grade D mains-powered smoke and heat alarms with battery backup
- Radio-frequency wireless interlinking between the alarms
- Concealed mains cable routes, installed without surface trunking
- Testing, commissioning and certification for the completed work
Testing, certification and handover
We tested and commissioned the installed alarms and provided certification for the completed work. At handover, we supplied the landlord with a complimentary Fire Safety Logbook and showed the client how to carry out the system's manual user tests and record the results internally. This helps reduce reliance on paid contractor visits for routine user checks; it does not replace required professional servicing or the responsible person's ongoing fire-safety duties.
Written and reviewed by
- Written by:
- Shashi Pal
- Position:
- NICEIC Approved QS
- Qualification:
- JIB Gold Card
- Professional membership:
- Associate Member - IFSM (8946)
Fire safety references
- Domestic fire alarm systemsBS 5839-6, using the edition and recommendations applicable to the premises.
- Mains electrical supplyBS 7671 IET Wiring Regulations, where applicable to the electrical work.
- Fire safety and HMO dutiesFire-safety legislation and HMO licensing requirements applicable to the property.
Fire alarm system disclaimer
This case study describes a mains-powered, radio-interlinked Grade D smoke and heat alarm installation at one six-bedroom HMO. The LD2 coverage and system arrangement reflect the requirements agreed for that project; they are not a specification for another property. Alarm grade, coverage and design should be determined for each premises against its fire-risk assessment, applicable standards and HMO licensing conditions.
Testing, commissioning and certification relate to the completed works described here. They do not replace the responsible person's ongoing fire-safety duties, routine user testing or any inspection and maintenance required under applicable standards, manufacturer instructions and the property's fire-risk assessment.
