For most of the last twenty years, wireless fire alarm systems were positioned as a compromise. Yes, they could detect a fire and yes, they could trigger a sounder, but installers, specifiers and insurers all treated them as the second-best option, used only when running cable was genuinely impossible.
That position has shifted. Wireless detection devices now hold EN 54-25 certification, sitting within the same BS EN 54 series that governs wired components. Battery technology has matured. Mesh architectures have eliminated single points of failure. And for a growing list of building types, wireless is no longer the compromise: it’s the better answer.
This piece is a decision guide for asset managers and building owners considering wireless. It explains where wireless is now clearly the right specification, where wired still wins, and what specific failure modes to ask your designer about before signing off either.
What the standards actually say
Two standards govern wireless fire alarm systems in the UK:
- BS EN 54-25: performance requirements for radio-linked components (detectors, manual call points, sounders, modules). This is the harmonised standard equivalent in scope to the wired component standards.
- BS 5839-1:2025: the UK code of practice for fire detection and alarm systems in non-domestic premises, in force since 30 April 2025. The current edition accepts wireless components installed to EN 54-25 as functionally equivalent to wired components for the same category and grade of system.
What this means in practice: a wireless fire alarm system, properly designed and installed to current standards, is compliant with the same legal duties under the Regulatory Reform (Fire Safety) Order 2005 as a wired system. The “wireless = lower compliance” assumption that lingered in some specification documents until the mid-2020s is no longer accurate.
Where wireless is now clearly the right choice
Heritage buildings and listed properties. Running fire alarm cable through a Grade I or Grade II listed building requires Listed Building Consent, conservation officer sign-off, and frequently a fight over every chase, every surface clip, every paint-matched cable cover. The wireless alternative (detectors that screw to a ceiling with two fixings, battery-powered call points that mount on a non-load-bearing wall) sidesteps the entire consent process while preserving the historic fabric. For listed estates and historic landmarks, wireless isn’t second-best; it’s the only viable answer in most circumstances.
Occupied residential buildings, particularly waking-watch removal. Where a residential block has been placed on a waking watch following an external wall survey or interim fire safety assessment, the operational cost is severe: typically £8,000 to £15,000 per month for a single mid-rise block, indefinitely. Standing the waking watch down requires installing a Category L5 (or higher) common-area fire detection and alarm system rapidly. Wired retrofit is slow and disruptive: communal lobby walls and ceilings opened, cable pulled, fire-stopping re-done, residents inconvenienced for weeks. Wireless retrofit takes a fraction of the time, doesn’t damage finishes, and lets the waking watch be stood down sooner, saving the landlord tens of thousands per month. This is the use case we delivered at the Unity Building in Liverpool, 26 storeys and 161 apartments covered in four weeks, and again across four high-rise towers in Tower Hamlets, where ending the waking watch saved more than £2.5m a year.
Phased construction or fit-outs. In a phased fit-out where one floor is occupied while another is being refurbished, wireless detection in the occupied zone can be relocated as the work progresses, without re-cabling. Wired systems require cable diversions, additional commissioning, and downtime per phase.
Buildings where the cable route is genuinely blocked. Cellars and basements with structural concrete, atria with unreachable high ceilings, plant rooms with grease and chemical contamination, areas with ATEX explosive-atmosphere requirements. Any environment where running and maintaining cable is uneconomic or unsafe makes a strong case for wireless.
Temporary buildings, marquees and event spaces. By definition not worth cable installation. Wireless deploys in hours and recovers when the event ends.
Where wired still wins
Very large, very dense estates. Wireless mesh networks have practical scale limits. A 50-storey commercial tower, or a hospital campus with hundreds of detectors per floor, sits at the edge of what current wireless infrastructure can reliably handle without performance compromises. Wired networks scale linearly without those constraints.
High-volume battery-replacement burden. Wireless devices run on lithium primary batteries with typical lives of 5–10 years on detection devices and 3–5 years on sounders. A 500-device wireless installation will generate approximately 50–100 battery replacements per year, every year. For property owners with constrained access (shutdown windows in a 24/7 operating environment, for example), the access cost of those replacements adds up. Wired systems have no equivalent recurring access cost.
High-RF-noise environments. Wireless mesh fire systems use the 868 MHz European licence-exempt band, which is generally clean. But in environments with high RF interference (broadcast facilities, industrial RF equipment, certain manufacturing plants), wireless reliability may not meet the required performance criteria. Wired systems are immune to RF interference by design.
New construction, where cable routing is trivial. If you’re installing a fire alarm into a building during the first-fix electrical works, the labour cost of running fire-rated cable alongside the rest of the electrical install is negligible. Wireless’s installation cost advantage disappears. In new build, wired typically remains the cleaner default unless one of the other use-cases above applies.
The questions to ask your fire alarm designer
Whether you’re presented with a wireless or wired proposal, the questions that matter are the same:
- What’s the design category (L1, L2, L3, L4, L5, M or P), and is it appropriate to the building’s use, occupancy and fire risk assessment?
- What’s the device count (sounders, detectors, call points, modules) and what battery-replacement schedule does that imply over the system’s design life?
- For wireless specifically: is every device covered by EN 54-25 certification, and certified to the same component categories as the equivalent wired devices?
- What’s the maintenance schedule, and who’s quoting against it? For social housing, reactive response time is now an enforceable compliance duty rather than a service-level nicety: Awaab’s Law has applied its 24-hour clock to emergency hazards since October 2025, and fire hazards formally join the regime on 30 November 2026.
- What’s the 10-year and 20-year total cost of ownership, including device replacement, battery replacement and routine maintenance? Wired and wireless can look similar at year 1 and diverge significantly at year 10.
- What happens when a detector loses contact? All wireless systems should signal a fault when a device drops off the mesh. Confirm the fault is signalled clearly, that the maintenance regime catches it, and that engineer attendance is within a defensible window.
How Gemini AMPM approaches the choice
We specify and install both wired and wireless fire alarm systems, and we select on the merits of the building, not the contractor’s margin. For residential retrofits and heritage buildings, wireless is now almost always the right answer, as delivered at the Unity Building in Liverpool and across four residential towers in Tower Hamlets. For new commercial builds and large institutional projects, wired remains our typical recommendation.
For an objective design review on an existing system, or a procurement-stage decision, get in touch or call 0330 043 0080.
This article is general guidance. Specific fire alarm system design must be undertaken by a competent designer working to BS 5839-1:2025 and the fire risk assessment for the building.
