Fire Alarm Installation London — BS 5839 Grade A, D, F

Grade A is a commercial addressable system with a control panel, zoned detection, sounders and manual call points — required for most non-domestic premises and large HMOs. Grade D is a mains-powered domestic system with battery backup, BS 5839-6 interlinked — the standard for London HMO licensing. Grade F is battery-only detection, only acceptable in the smallest, lowest-risk lets where a fire risk assessment supports it.

Almost certainly. Every London borough we work with requires at least a Grade D LD2 system in licensed HMOs — that means mains-powered, interlinked detectors covering escape routes and high-risk rooms. Larger HMOs (5+ storeys, 6+ occupants in some boroughs) often require Grade A. Your fire risk assessment is the document that confirms the grade.

Three drivers: number of detectors (driven by room count and escape route layout), cable routing difficulty (surface-clipped vs chased and re-plastered), and grade. A 4-bed HMO needing 6 interlinked detectors with surface cabling is straightforward; the same property requiring concealed cabling and a chimney heat detector adds significant labour.

Access to each room is required, but tenants do not need to be home all day. We coordinate room-by-room with the property manager, typically completing a 4-bed HMO in one day. Power is off only briefly while the supply circuit is tapped.

Commissioning is the one-off test and certificate issued when the system is first installed — it proves the design works as built. Maintenance is the ongoing weekly user test, six-monthly engineer test and annual full system check required under BS 5839 throughout the system life. We bundle both at install so you have a single contractor for the life of the system.

The Building Safety Act 2022 applies to higher-risk residential buildings (18m+ or 7+ storeys) and tightens the duty on the Accountable Person to maintain fire safety systems. For most HMOs and commercial sites the BS 5839 install + maintenance regime already discharges the duty — we format paperwork so it fits the golden-thread requirement.

Yes — Grade A panels can drive emergency lighting test relays, and we coordinate sounder coverage with luminaire positions so escape routes are both lit and audible. We also test and certify the emergency lighting under BS 5266 at the same visit.

Yes — common in HMOs converted from period houses with a single stairwell. The fire alarm panel drives the AOV actuator on activation. We design the interface, install the cabling and commission both systems together so the certification matches.