Fire Alarm Systems: Conventional vs Addressable

2 a.m., and the panel says "Zone 3"

At two in the morning the fire panel in a hotel lobby goes off and shows only "Zone 3 in alarm". Zone 3 is the whole second floor: 20 rooms, guests asleep. The night guard has to run and knock on doors one by one. If it's a real fire, every minute counts. If it's a false alarm, a whole floor of guests is awake and staff start to distrust the system. So the main question when choosing a fire alarm system isn't "which brand". It's "how precisely, and how quickly, do you need to know where the fire is?"

Two approaches, one question: where is the fire?

Every fire alarm system does the same basic job. A detector senses smoke or heat, the panel decides, the sounders go off. The difference is how precisely the panel can tell you where it happened.

Conventional (zoned). Several detectors are wired in parallel on one zone circuit, terminated with an end-of-line resistor. When any detector triggers, the panel only knows "Zone 3 in alarm".

Addressable. Every detector, call point and module on the loop has its own address. The panel shows "Smoke detector 2-047, Level 2 store room". It also reads an analog value from each detector, so it can warn you that a head is getting dirty before it causes a false alarm.

There is a third option: wireless addressable systems. They suit old or heritage buildings where you can't chase walls or run conduit, but device batteries need replacing periodically and the cost per point is higher.

Side by side

That last row matters more than people expect. Once you buy an addressable panel, you are tied to its protocol for the next 10–15 years. Before ordering, ask whether spares are stocked by distributors in Thailand or have to come from overseas.

What we'd choose, and when

For shops, small offices or warehouses with up to roughly 30–40 detectors and few rooms, a sensibly zoned conventional system is enough, and local technicians can service it easily. For hotels, hospitals, multi-storey buildings or anywhere with many rooms, we recommend addressable. In an 80-room hotel, knowing "room 312" straight away is the difference between a two-minute check and a fifteen-minute search.

Before design, always check the building designer's requirements and the project specification.

Detector types: put the right one in the right room

• Photoelectric (optical) smoke: offices, bedrooms, corridors, server rooms.
• Heat (fixed or rate-of-rise): kitchens, car parks, generator rooms, anywhere with normal smoke or steam.
• Multi-sensor (smoke + heat): where you want fewer false alarms without slowing detection.
• Beam detectors: high-ceiling warehouses and factories where point detectors are hard to reach.
• Aspirating: server rooms and high-value spaces that need the earliest warning.

Spacing: under BS 5839-1, on a flat ceiling, no point in the room may be more than 7.5 m from a smoke detector or 5.3 m from a heat detector. In a narrow corridor that lets smoke detectors sit up to about 15 m apart. NFPA 72 uses a different method, so use the figures from whichever standard the project follows.

What we often see in Laos: a smoke detector in a hotel kitchen false-alarms every week, so staff remove it or disable the zone. In the rainy season, high humidity and insects inside detector heads also cause false alarms. Choose the detector for the room on day one.

Sizing the panel

1. Count every device: detectors, call points, sounders, input/output modules.
2. Addressable: keep each loop roughly 20–25% below its limit for expansion, and check the voltage-drop calculation for sounder current.
3. Conventional: lay out zones so each is easy to search, and keep spare zones.
4. Standby batteries: BS 5839-1:2025 (which replaced the 2017 edition from April 2025) sets a default of 24 hours standby plus 30 minutes in alarm, and requires batteries to be labelled with their installation date. NFPA 72 uses 24 hours standby plus 5 minutes of alarm (15 minutes for emergency voice evacuation systems).

Worked example: an 80-room hotel on four floors

We would split this into two loops (floors 1–2 and floors 3–4) of about 95 points each. On loops rated for 200 points, that leaves half the capacity for growth, and a problem on one loop doesn't take out the other. Fit isolators at least between every floor.

Batteries: say the panel draws 0.35 A on standby and 2.5 A in alarm: (0.35 × 24) + (2.5 × 0.5) = 9.65 Ah. Add 25% for battery ageing and you need about 12 Ah, so two 12 V 17 Ah batteries in series for 24 V. Always use the real current figures from the panel and device datasheets.

Doing the same building conventionally would take roughly 16–20 zones to locate a fire quickly enough, and the extra cabling and labour eat up most of the saving on devices.

Standards

Projects in Laos usually reference international standards: NFPA 72 (US), EN 54 (European product standards) and BS 5839-1 (UK design code). Foreign-funded projects and international hotel brands often specify one in the contract. The key is to pick one standard and apply it consistently from design through commissioning tests. Don't mix them.

Integration with other systems

• Access control: on alarm, doors on escape routes must unlock automatically. Our preferred method is a relay from the fire panel that cuts power to fail-safe magnetic locks directly, rather than relying only on a software command through the access control system. If the network is down, the doors must still open.
• CCTV: send the alarm signal to the NVR or VMS so cameras in that zone pop up and record. It helps the control room verify quickly.
• Lifts, fans and air conditioning: recall lifts to the designated floor and shut down AHUs so smoke doesn't spread. Design this with the mechanical engineer.

What changes in Lao conditions

• Frequent power cuts: the panel batteries get real use almost every week, so they wear out faster than the datasheet suggests. Check them every six months and replace them on age, not when the panel finally shows a fault.
• Lightning: loops running between buildings at mines and factories pick up surges easily. Use fibre between panels, or proper surge protection.
• Dust: smoke detectors at mines and factories get dirty fast. Consider heat, beam or aspirating detection with filters.
• Technicians: addressable panels need a technician with the programming software and the panel passwords. Make sure you receive the configuration file and access codes at handover.

Testing and maintenance

• Weekly: test one call point on rotation and check the panel shows no faults.
• Every six months, or as your standard requires: test detectors with test smoke or a heat tool, check batteries and sounders.
• Annually: test every device, and test the door, lift and CCTV interfaces for real.
• Record everything in a logbook. Dust and humidity age detectors faster than in cooler climates, so clean or replace them per the manufacturer's guidance.

What we keep finding

1. Zones disabled for months because of false alarms, and nobody re-enabled them.
2. Detectors still wearing the red dust covers fitted during construction.
3. Swollen or expired batteries in the panel, with no date label.
4. Escape doors held by magnetic locks that aren't connected to the fire panel at all.
5. No zone chart next to the panel, so the guard can't make sense of the display.
6. The original contractor gone, along with the panel passwords, so nobody can change the programming.

Send us your floor plans and room list, and we'll propose a zone or loop layout with the right detector for each room. Our fire alarm page shows the full scope of what we install.