security
Fire alarm systems
A small commercial fire alarm system costs £1,200 to £4,000 installed. The figure that decides it is the category, a letter and a number from BS 5839 that says how much of the building is covered and what the system is protecting: the people in it, or the building itself.
What this covers
What it costs. A small commercial system is £1,200 to £4,000 installed, and a larger addressable system across several floors £6,000 to £25,000. Full cost breakdown.
What the job covers
- Designing and installing systems to BS 5839
- Conventional and addressable panels
- Weekly call point tests and the servicing schedule
- Detection in communal areas of flats
- Fault finding on panels in permanent fault
What is involved
Categories are the language of this job and they are worth understanding before reading a quote. An M system is manual only: call points and sounders, no automatic detection. The L categories protect life, from L5 covering a specific risk, through L4 in escape routes, L3 adding rooms opening onto them, up to L1 with detection almost everywhere. The P categories protect property, usually because an insurer asked. Two quotes for the same building can differ by thousands and both be right, if one is L4 and the other is L1.
The choice between conventional and addressable follows building size. A conventional panel knows which zone has activated, so a two zone shop is perfectly served by one. An addressable panel knows which device has activated, which in a building with forty detectors across three floors is the difference between attending a fire and searching for one. Addressable costs more per device and less per fault call out, and above roughly twenty devices it usually wins.
The system is only as good as what happens after it is switched on. A weekly call point test, rotating through the call points so each is proved over time, goes in the log book. A periodic service by a competent engineer, normally twice a year, checks detectors, batteries and the panel. The log book is what a fire officer or an insurer asks for, and an empty log book in a building with an immaculate system is the finding that causes trouble.
Choosing someone for the job
Ask which category the quote is for and get it in writing, because that is what makes two prices comparable. Ask whether it is conventional or addressable and why, for this building. Ask what the servicing interval and annual cost are. Ask whether the handover includes a log book, a zone chart at the panel and the certificate.
Common questions
What category do I need?
It follows the fire risk assessment for the building rather than a general rule. Common outcomes are L4 or L3 for premises with sleeping risk or escape routes that need protecting, and M for a small single storey unit. An insurer may impose a P category on top.
Conventional or addressable?
Conventional for small premises with a handful of zones. Addressable once the device count climbs, because knowing which detector activated saves time on every alarm and every fault. The crossover is usually around twenty devices.