Who Really Decides the Fire Alarm Category?
Clarifying Responsibility Under BS 5839-1 (2025) – A Fire Risk Assessor’s Perspective
The recent guidance issued by the Fire Industry Association (FIA), aligned with the 2025 update to BS 5839-1, was intended to clarify the correct use of fire alarm system categories. Despite good intentions, many Responsible Persons, managing agents and contractors are left asking the same question: who is actually responsible for deciding the fire alarm category? The guidance correctly reinforces that this responsibility does not sit with the fire alarm installer or contractor. However, by referring broadly to a “fire safety specialist”, it can still blur the boundary between a fire risk assessor and a fire engineer, a line that already causes widespread confusion across the industry. This article explains that boundary clearly, from a Responsible Person’s perspective, and sets out what should reasonably be expected from each role.
Fire alarm categories: unchanged, yet still misunderstood
Fire alarm categories (L1–L5, M, LD and so on) have remained fundamentally unchanged for many years. The confusion persists not because the categories are complex, but because decisions are often made too late in the process, responsibility is pushed between parties, and competence is assumed based on job title rather than scope. One point is clear and worth repeating: fire alarm designers and installers should not be deciding the category. Categories should be determined based on the fire safety objectives for the premises, then designed and installed to meet that stated requirement.
The Responsible Person’s legal position
Under the Regulatory Reform (Fire Safety) Order 2005, the Responsible Person must ensure a suitable and sufficient fire risk assessment is in place, implement appropriate fire detection and warning arrangements, and appoint competent persons to support those duties. The Responsible Person is not expected to interpret British Standards personally, design fire alarm systems, or undertake fire engineering analysis. Instead, the Responsible Person relies on competent advice that is properly scoped and clearly documented, creating a defensible audit trail for decisions and actions taken.
What a fire risk assessor should do
A competent fire risk assessor should assess the premises, occupancy and fire risks, identify the fire safety objectives, and determine whether life protection, property protection or both are required. Where the premises is straightforward and the outcome aligns with recognised benchmark guidance, the assessor should be able to state the appropriate fire alarm category and record the reasoning within the fire risk assessment. In those situations, this is entirely appropriate and is often the most practical way to give the Responsible Person clarity and direction. A fire risk assessor should also be clear about the limits of that decision. They should not attempt to engineer reduced detection where guidance would normally require more, justify departures based on management controls alone, or rely on evacuation modelling or response-time assumptions. Those are matters for fire engineering, not fire risk assessment.
Where the fire engineer’s role begins
A fire engineer is required where the proposed alarm category deviates from benchmark guidance, relies on compensatory measures, forms part of a wider engineered fire strategy, or is linked to more complex premises features such as phased evacuation, extended travel distances, or non-standard layouts and use. Put simply, fire risk assessment identifies the need, and fire engineering justifies the exception. This distinction matters because it protects the Responsible Person from ambiguous advice and ensures the right expertise is used when the risk profile or building complexity demands it.
The same boundary exists elsewhere in fire safety
This distinction is not unique to fire alarm categories. A fire risk assessor may identify concerns relating to fire compartmentation, fire doors, service penetrations and external wall construction, but the assessor does not certify fire-resisting construction, confirm the adequacy of fire stopping, or assess the combustibility or system performance of an external wall system. In practice, compartmentation concerns may require intrusive inspection or fire engineering input, and external wall systems may require a separate Fire Risk Appraisal of External Walls (FRAEW) undertaken by a suitably competent specialist. The role of the fire risk assessor is to identify, record and escalate, not to engineer or certify.
A real-life example: from a Responsible Person’s perspective
A Responsible Person manages a two-storey office with ancillary storage, occupied during normal working hours. They commission a fire risk assessment and want a clear outcome that can be actioned. A competent fire risk assessor assesses occupancy, layout, means of escape and risk profile, refers to benchmark guidance for typical office premises, and determines that Category L3 detection is appropriate. The assessor records the category and the reasoning within the fire risk assessment and confirms that, because the recommendation aligns with recognised guidance, no fire engineering justification is required in this scenario. The fire alarm designer then designs a compliant L3 system and the installer installs it as specified. The Responsible Person gets clarity, a clear audit trail, and an outcome that can be maintained and evidenced. Where confusion often arises is when Responsible Persons are told that the installer or contractor will advise on the alarm category, or that fire engineering input is required simply to confirm a benchmark category such as L3 for a straightforward office. In many cases, that approach delays compliance and encourages responsibility-shifting rather than improving safety.
Why clarity matters now more than ever
In the wake of major fire safety reforms introduced following tragic events intended to improve fire safety, the industry should be striving for clarity and confidence. Poorly defined guidance, without clear boundaries, can create defensive practice, responsibility-shifting, increased cost and uncertainty for Responsible Persons, and delays in implementing practical control measures. Confusion does not improve safety. Clarity does.
The correct, balanced position
From a Responsible Person’s perspective, a fire risk assessor should be able to state the appropriate alarm category where it aligns with benchmark guidance, and any departure from guidance should be clearly flagged and referred for fire engineering input. Designers design and installers install. Just as a fire risk assessment does not replace a compartmentation survey or an FRAEW, it should not be treated as a substitute for fire engineering where engineered solutions are proposed.
Final thoughts
Fire alarm categories are not a design preference or an installer’s decision. They are a fire safety outcome, derived from risk, competence and clear objectives. Clear roles protect Responsible Persons, fire risk assessors, designers and contractors, and most importantly building occupants. Guidance should reduce confusion, not reinforce it.