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Fire & Security FAQ Database

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Technical guidance only. Confirm current project requirements against the applicable standards, legislation, system documentation and site-specific fire strategy.

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How should AOV (automatic opening vent) actuation be tested?

Trigger the mapped detection zone or control input and confirm the vent opens fully within the expected time, then closes/resets correctly. Check the manual override controls at the fire service access point, the standby supply, and that fault monitoring reports to a supervised location. Wind and weather interlocks can legitimately block a test — understand the control logic before recording a failure. Note travel times and any struggling actuators; they fail on the day they're needed, not on the bench. Standards are referenced for orientation only — always confirm requirements against the current edition of the applicable standard, the site's fire strategy and manufacturer documentation.

GeneralAll systemsBS EN 12101AOV actuation
What should engineers know about CCTV camera analytics?

Analytics are only as good as the scene: mounting height, angle, lighting and a clean lens decide whether detection rules work. Commission analytics against agreed test scenarios (walk tests at the required distances) and record the results; re-verify after any camera move, refocus or firmware update. Watch false-trigger rates in the VMS — an analytic that cries wolf gets ignored, which is operationally worse than no analytic at all. Standards are referenced for orientation only — always confirm requirements against the current edition of the applicable standard, the site's fire strategy and manufacturer documentation.

GeneralAll systemsBS EN 62676camera analytics
How should fire alarm defects be prioritised?

Judge each defect by its effect on the system's ability to detect and warn: anything that stops detection or alarm in an occupied area, or takes the panel or signalling down, needs immediate action and formal notification to the responsible person. Degraded redundancy, single-device faults and non-urgent wear items follow, with agreed timescales. Put the priority and the consequence in writing — clients act on "this means the second floor has no automatic detection" far faster than on a code. Standards are referenced for orientation only — always confirm requirements against the current edition of the applicable standard, the site's fire strategy and manufacturer documentation.

GeneralAll systemsBS 5839-1defect prioritisation
Why do detectors report dirty or drift warnings, and what should I do?

Optical chambers accumulate dust, insects, steam residue and decorating debris; the analogue value creeps up until the panel flags contamination or pre-alarm. Check the environment first — a detector near an air-handling vent or in a workshop will foul repeatedly no matter how often it's swapped. Clean or replace per the manufacturer's guidance (many heads are exchange-only), record the analogue values before and after, and note repeat offenders: a location that fouls every few months needs a detection-type review, not another clean. Standards are referenced for orientation only — always confirm requirements against the current edition of the applicable standard, the site's fire strategy and manufacturer documentation.

GeneralAll systemsEN 54-7detector contamination
How do I reduce false alarms on a fire alarm system?

Start with the event log, not opinions: identify which devices, times and conditions generate the unwanted alarms. Then match the fix to the cause — wrong detector type for the environment (steam, dust, cooking), detector siting too close to vents or kitchens, transient activities without temporary management, or genuine faults presenting as alarms. Multi-sensor or heat detection, relocation, cause-and-effect delays where the standard permits them, and client housekeeping all have their place. Change one thing at a time and monitor the log after each change so you know what actually worked. Standards are referenced for orientation only — always confirm requirements against the current edition of the applicable standard, the site's fire strategy and manufacturer documentation.

GeneralAll systemsBS 5839-1false alarm reduction
What makes a good fire alarm site survey?

Walk the whole building, not the drawings: record construction, ceiling heights and voids, occupancy and sleeping risk, environmental challenges (dust, steam, humidity), existing equipment and its condition, cable routes, and anything that will affect detector choice or coverage. Photograph the panel, a sample of devices, and problem areas. Talk to whoever manages the building — the operational reality they describe is the difference between a design that works and one that false-alarms for a year. Standards are referenced for orientation only — always confirm requirements against the current edition of the applicable standard, the site's fire strategy and manufacturer documentation.

GeneralAll systemsBS 5839-1site survey method
What safety controls apply when working on suppression release circuits?

Before touching anything, isolate the releasing circuit or fit the actuation blocking devices per the manufacturer's procedure, and prove the isolation — an accidental discharge can be lethal and is always expensive. Agree the isolation with the responsible person, tag it, and record it. Test detection and control logic with the release physically prevented, then restore and verify the system is back to automatic with the isolation removed. Never leave site with a release circuit isolated and nobody formally told. Standards are referenced for orientation only — always confirm requirements against the current edition of the applicable standard, the site's fire strategy and manufacturer documentation.

GeneralAll systemsBS 5306suppression release safety