Getting Started — Fire Alarms
Purpose
This document is the starting point for any engineer working on fire alarm systems at Wilsons. It covers what fire alarms are for, the legal and standards framework, the types of systems we install and service, and what level of competence is needed before working on fire alarms independently.
Why Fire Alarms Are Different
Fire alarms are life-safety systems. Unlike a CCTV system or an intruder alarm, a failure in a fire alarm system can directly cost lives. This changes how we approach everything:
- Installation quality is non-negotiable. A poorly wired intruder alarm might cause a false alarm. A poorly wired fire alarm might fail to warn people in a building that is on fire.
- We work to standards. Fire alarm work in the UK is governed by BS 5839-1 (for non-domestic) and BS 5839-6 (for domestic). These are not optional guidance — they are the framework for everything we do.
- Documentation is mandatory. Every fire alarm installation and service visit requires a completion certificate or service report. This is a legal requirement.
If you are unsure whether something is compliant or correct, stop and ask. In fire alarm work, uncertainty is a prompt to get confirmation, not to proceed and hope.
The Regulatory Framework
BS 5839-1
The main standard for fire detection and alarm systems in non-domestic premises (commercial, industrial, schools, hotels, etc.). Covers system design, detection types, wiring standards, commissioning, and maintenance.
BS 5839-6
Covers fire detection and alarm systems for domestic premises (houses, flats, HMOs). Most domestic fire alarm work falls under this standard — smoke alarms, heat alarms, and interlinked systems in dwellings.
Building Regulations — Part B
Fire safety requirements for new buildings and major refurbishments. Sets minimum requirements for fire alarm provision in different building types.
Regulatory Reform (Fire Safety) Order 2005
All non-domestic premises must have a fire risk assessment. The responsible person for the premises is legally accountable for fire safety.
System Categories — BS 5839-1
| Category | Coverage | Purpose |
|---|---|---|
| L1 | Throughout the building | Full life protection — automatic detection everywhere |
| L2 | Defined areas (escape routes + high-risk areas) | Life protection in critical areas |
| L3 | Escape routes only | Life protection on escape routes |
| L4 | Corridors and circulation areas | Basic life protection |
| L5 | Specified areas only | Partial coverage as specified |
| M | Manual call points only | No automatic detection |
| P1 | Throughout the building | Property protection — full coverage |
| P2 | Defined areas only | Partial property protection |
L categories = Life protection. P categories = Property protection. M = Manual only.
The fire risk assessment will specify the minimum category required. Wilsons installs to the specified category — never below.
System Types — Conventional vs Addressable
Conventional Fire Alarm Systems
Detectors and call points are wired in zones (circuits). The panel knows which zone has activated but not which specific device.
- Simpler, lower cost
- Suitable for smaller premises with straightforward layouts
- Zone-level identification only
C-Tec CFP range — conventional panels used for smaller installs.
Addressable Fire Alarm Systems
Every device has a unique address. The panel identifies exactly which specific detector or call point has activated.
- Precise device-level identification
- Suitable for larger, more complex premises
- Can disable individual devices, view device status, configure complex cause-and-effect
C-Tec ZFP range — addressable panels used for larger or more complex installations.
Domestic Fire Alarms (BS 5839-6)
Grades (installation standard):
- Grade D — mains-powered interlinked detectors with battery backup ← most common in domestic installs
- Grade F — battery-only detector (lowest grade — standalone, not interlinked)
Categories (coverage):
- LD1 — automatic detection throughout the dwelling
- LD2 — detection in highest-risk rooms and escape routes
- LD3 — detection on escape routes only
Most residential installs: Grade D, LD2 — mains-powered interlinked smoke alarms on escape routes plus heat alarm in kitchen.
Wilsons' Scope of Fire Alarm Work
- Domestic interlinked systems — Grade D, mains-powered smoke and heat alarms
- Small commercial conventional systems — C-Tec CFP-based
- Addressable systems — C-Tec ZFP-based for larger premises
Competency
- New engineers: Do not commission or certify a fire alarm system independently until signed off by a senior engineer
- Service work: Routine maintenance under senior engineer guidance
- Commissioning: Requires solid understanding of BS 5839 and the specific panel type
- Certification: Completion certificates are legal documents — they must be accurate