PAS 79 and Fire Risk Assessment Methodology
Behind almost every fire safety decision in a building is a fire risk assessment — and how that assessment is carried out matters. PAS 79 is a widely-used, structured methodology for doing and documenting fire risk assessments, giving assessors a systematic approach rather than an ad hoc one. It is not the fire alarm engineer's job to produce the assessment, but the assessment shapes what the fire alarm needs to be, so understanding where it comes from is worthwhile. This guide gives an orientation.
The central point is that PAS 79 provides a structured methodology for fire risk assessments, which drive many fire safety decisions — including what the fire alarm needs to be — while the legal duty sits under the Fire Safety Order.
Who this is for
This is for competent fire alarm engineers who want to understand the fire risk assessment context of their work. The experience level assumed is competent engineer. Use this as orientation; fire risk assessments are carried out by competent assessors, and the authoritative sources are PAS 79 and the Fire Safety Order. The fire alarm follows BS 5839-1, informed by the assessment.
What PAS 79 is
PAS 79 is a publicly available specification that provides a methodology for carrying out and documenting fire risk assessments. It sets out a structured approach that assessors can follow, helping make assessments systematic, thorough and consistent rather than dependent on individual habit. It is guidance on how to assess, not a legal instrument in itself. Different parts address different building types. The authoritative source is PAS 79 itself and the relevant guidance. For an engineer, the useful recognition is that a good fire risk assessment follows a recognised method, and PAS 79 is one of the most widely used.
Guidance, not law
It is important to place PAS 79 correctly relative to the law. The legal requirement, under the Regulatory Reform (Fire Safety) Order 2005, is for a suitable and sufficient fire risk assessment; the law does not mandate a particular methodology. PAS 79 is one widely-used, structured way of achieving that, but an assessment can be compliant using PAS 79 or another suitable approach, provided it is genuinely suitable and sufficient. Which methodology is used is a matter for the competent assessor. So PAS 79 supports meeting the legal requirement in a structured way, without being the requirement itself. Keeping the distinction — legal duty versus methodology — clear avoids the common error of treating a method as the law.
The assessment and the fire alarm
The connection to fire alarm work runs through the assessment's scope. The fire risk assessment considers the fire safety of the whole premises, and the fire alarm is one of the measures it takes into account — for example whether the detection and warning provided are appropriate for the risks identified. So the assessment can directly influence what the fire alarm needs to be, and the fire alarm engineer's work supports the outcome the assessment calls for. The assessment follows the Fire Safety Order and methodologies such as PAS 79; the fire alarm follows BS 5839-1, informed by the assessment. The two are linked: a change in the assessed risk can change what the alarm should do.
The engineer's understanding
For the engineer, the practical position is to respect the assessment's role and support it well. Understand that the fire risk assessment drives many fire safety decisions, including expectations of the fire alarm, and that PAS 79 is a common structured methodology for it, carried out by a competent assessor rather than the fire alarm engineer. Keep the fire alarm work aligned to what the assessment requires under BS 5839-1, and provide accurate information about the system to support the assessment. From field experience, an engineer who understands how the assessment shapes the alarm — and who feeds it good information — contributes to a more coherent result. Verify specifics against PAS 79 and the Fire Safety Order.
Common points to check
For engineers, the practical points are recognising the assessment drives the alarm's expectations, that PAS 79 is a method rather than the law, and that the assessment is the competent assessor's work. Confirming the fire alarm aligns with the assessment is the essential check.
When not to rely on this alone
When not to use this article: do not use it to carry out a fire risk assessment. That is the competent assessor's work, following PAS 79 or another suitable methodology and the Fire Safety Order; the fire alarm follows BS 5839-1, informed by the assessment.
Relevant standards
Fire risk assessment methodology is addressed by PAS 79, supporting the legal duty under the Regulatory Reform (Fire Safety) Order 2005; the fire alarm follows BS 5839-1, a code of practice, informed by the assessment. Separate the legal duty from the methodology, and always work to current editions and guidance.
Professional disclaimer
This is an educational and workflow resource for competent engineers and does not replace PAS 79, the current British Standards, the Fire Safety Order, or competent judgement. It is orientation only; verify specifics against the authoritative sources.
Related documentation
Use this with PAS 79, the Regulatory Reform (Fire Safety) Order 2005 and the current BS 5839-1. Keep the fire alarm aligned to the fire risk assessment, and provide accurate system information to support it.