Fire alarm · BS 5839-1
Fire alarm servicing intervals under BS 5839-1
Who tests a fire alarm system, how often, and what has to be recorded — the weekly user test, periodic inspections by a competent person, and the checks that belong on the certificate.
The short version
BS 5839-1 splits fire alarm maintenance between two people: the responsible person on site, who does simple routine checks, and a competent person — usually a fire alarm engineer — who carries out periodic inspection and servicing. The intervals below are the ones most UK premises work to; the exact regime for a given building is set by the system's design and the servicing organisation's judgement.
| Check | Who | How often | Recorded where |
|---|---|---|---|
| Manual call point test (a different one each week) | Responsible person | Weekly | Site log book |
| Periodic inspection & servicing | Competent person | Typically every 6 months | Servicing certificate |
| Full annual checks (all devices tested over the year) | Competent person | Every 12 months, across visits | Servicing certificate |
| Standby battery condition | Competent person | Each periodic visit | Servicing certificate |
Key point: "every six months" is the usual interval between competent-person visits, but the standard's real requirement is that every device is tested at least once in each 12-month period. That's why the periodic certificate needs to show which detectors were tested, not just that "a sample" was.
The weekly user test
Once a week, someone on site operates one manual call point and confirms the panel goes into alarm and the sounders operate. A different call point should be used each week so that, over time, all of them are tested. The result — including the call point used and any faults — goes in the site log book.
This is not a certificate-level activity, and it isn't something the servicing engineer signs for. But when the engineer arrives for a periodic visit, the log book is one of the first things they should look at: a log book with a six-month gap in it is a finding in its own right.
Periodic inspection and servicing
The competent-person visit is where the certificate is produced. A typical six-monthly visit covers:
- Checking the log book and any faults or false alarms since the last visit
- Panel checks: clock, fault indications, repeater panels, event log
- Function-testing a proportion of detectors — rotated so every device is covered within 12 months
- Testing every manual call point over the year, and all sounders and beacons
- Ancillary interfaces: door holders, plant shutdown, lift grounding, signalling to an ARC
- Standby power: battery voltages on float and on load, charger output, and the capacity calculation
- Visual inspection of wiring and devices for damage, obstruction or changes to the building
- Confirming the zone chart at the panel still matches the building
Each of these is a pass / fail / not-applicable outcome, and anything that fails should appear on the certificate as a defect with a severity — not buried in a free-text notes box.
Why the battery calculation matters
A fire alarm system has to keep running through a mains failure — typically 24 hours in standby followed by a period in full alarm. Whether the fitted batteries can actually do that is a calculation, not a guess: the required capacity depends on the system's quiescent current, its alarm current, and the durations required.
The BS 5839-1 method is, in outline: 1.25 × [(standby hours × quiescent current) + 1.75 × (alarm current × alarm hours)]. The result is compared with the rated capacity of the batteries fitted. A battery that meets the figure today but is four years old is still due for replacement.
This is one of the places paper certificates go wrong most often: the readings are written down, but the calculation isn't done, so the certificate can't say whether standby capacity is actually adequate. Kerova's fire alarm certificate does the arithmetic from the readings entered and flags batteries that are under capacity or over age.
False alarm review
The periodic visit should also review the number of false alarms in the previous 12 months against the number of detectors. Rates above roughly four per 100 detectors per year warrant a preliminary investigation; above five, a more thorough one. The point is to catch a poorly sited detector or a badly managed kitchen before it turns into a fire service non-attendance policy for that building.
What the record has to show
Whatever format the certificate takes, an auditor or insurer will want to see:
- The site, system and panel details, and the system category (L1–L5, M, P1, P2)
- The date of the visit and the name and organisation of the competent person
- Which zones and devices were tested, and the results
- The battery readings and the resulting capacity assessment
- Every defect found, with a severity and a recommended action
- An overall verdict, and the date the next visit is due
- The signature of the competent person and, ideally, the client's acknowledgement
The more of this that is structured data rather than handwriting, the easier it is to prove compliance later — see what makes a certificate compliant.
This guide is general information for UK fire & security companies, not legal or engineering advice. Always work to the current edition of the relevant standard and your own competent-person judgement.
See this on a real certificateKerova builds the register, readings and verdict into the certificate itself.
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