An interlinked smoke alarm system is one where every detector talks to every other detector. Trigger one alarm in the kitchen and the bedrooms sound within ten seconds — critical when occupants are asleep behind closed doors. BS 5839-6 has mandated interlinked Grade D detection in HMOs since 2019, and every London licensing borough treats it as the audit baseline for rental properties.
There are two ways to interlink. Hard-wired uses a 3-core+E cable between detector bases — the cleanest solution in new builds, rewires and unoccupied refurbs. Radio-linked uses the Aico Ei3000RF module (or equivalent FireAngel and Kidde models) and is the only practical option in occupied period properties where chasing the walls is not viable. Both methods give identical BS 5839-6 compliance and identical certification.
Electrician London surveys, designs and commissions both. The survey decides which method fits the property — and which combination, because hybrids (wired ground floor, radio-linked extension) are common in London terraces that have grown over the decades.
Why Electrician London
BS 5839-6 LD2 coverage
Escape routes plus kitchen heat and living-room smoke. The HMO licensing baseline, designed to the schedule, certified at commissioning.
Wired or radio-linked
Hard-wired 3-core+E for new work, Aico Ei3000RF radio for occupied retrofits. Same compliance, same certificate, choice of method.
Grade D mains + battery
Mains-powered with sealed 72-hour battery backup. Ten-year head life, no annual battery change, no nuisance chirp.
Certificate + logbook
BS 5839-6 commissioning certificate and logbook entry handed over on the day. Council-ready for HMO licensing renewals.
Interlinked smoke alarm pricing
Per-point pricing on all install work. London-wide, no ULEZ or congestion surcharge.
Wired interlinked 3-4 alarms
Typical 1-2 bed HMO or family home
£550
Wired interlinked 5-7 alarms (HMO)
Standard 3-4 bed HMO with kitchen heat
£950
Radio-linked retrofit
Aico Ei3000RF — no plaster damage
£210 / point
Replacement add to existing interlink
Like-for-like swap on existing base
£180 / point
Annual inspection + test
Full BS 5839-6 engineer test, all alarms
£85
What's included
- BS 5839-6 LD2 design schedule
- Aico, FireAngel or Kidde alarm heads
- Hard-wired 3-core+E or radio-linked interconnect
- Mains supply from the lighting circuit
- Commissioning test triggering full interlink
- BS 5839-6 commissioning certificate
- Minor Works Electrical Installation Certificate
- Logbook entry and install photographs
Frequently asked questions
Is interlinked detection a legal requirement?
For HMOs in England — yes. BS 5839-6:2019 mandates interlinked Grade D detection in HMOs, and every London licensing borough treats this as the audit baseline. For owner-occupied homes the law is technically met by individual alarms on each storey, but interlinking is strongly recommended and is required for new-build under Building Regulations Part B.
Wired or radio-linked — which is better?
Compliance is identical. Hard-wired is the cleanest solution when the property is empty or being rewired anyway. Radio-linked is the only sensible choice in occupied period properties where chasing the walls would mean strip-out and re-decoration. We routinely install hybrid systems — wired where cable runs are easy, radio where they are not.
How does radio-link work without chasing walls?
Each Aico Ei3000-series base accepts a snap-in Ei3000RF radio module. Once paired, the modules form a self-healing mesh — trigger any alarm and every alarm sounds within ten seconds. Range is around 100m line-of-sight, well over what any London terrace needs. Each base still wires to the lighting-circuit mains.
Can I mix Aico, FireAngel and Kidde?
No. Radio-link protocols are manufacturer-specific. The whole system must be one brand, although the brand can be any of the three. Hard-wired bases can technically mix, but BS 5839-6 commissioning is easier when the install is single-brand throughout.
How long does a 6-point retrofit take?
A six-point radio-linked retrofit in an occupied HMO typically takes one engineer one full day. A six-point hard-wired install in an empty property runs slightly longer because of cable routing and making good. Both finish with same-day certification.
Will the system false-alarm from cooking?
Not if it is designed correctly. Kitchens get heat alarms (not smoke), and the nearest smoke alarm is positioned at least 7.5m from the cooker or behind a door, per BS 5839-6 Annex C. Optical smoke heads tolerate steam better than ionisation, which is why we no longer install ionisation alarms in any domestic setting.
How do I test it after install?
Press and hold the test button on any one alarm. Within ten seconds every other alarm in the interlink should sound. Release the button and they should silence within thirty seconds. BS 5839-6 recommends a weekly user test (any occupant can do it) and an annual engineer test that we offer at £85.
What happens when an alarm reaches end-of-life?
Ten years from manufacture the head chirps end-of-life and must be replaced. We replace like-for-like at £180 per point on existing wired bases or £210 per point on radio-linked. Mixed-age systems are common in long-tenure HMOs and we replace heads in tranches as they age out.
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