When a sprinkler opens, the signal must not simply make a noise in the pump room — someone has to hear it, log it and act on it. Annex I describes three reliability levels for alarm transmission: direct to the fire service, to a monitoring centre, or local only. Which one suits your facility?
At a textile warehouse the sprinklers operated at 02:30. The pump started, the flow alarm sounded, and a twelve-sprinkler fire was knocked down. The watchman was on a cigarette break with his phone on silent. The fire service arrived at 04:50, called by a neighbour — by then the warehouse was well alight. The sprinklers did their job; the alarm transmission did not. The site had local alarms only, with no 24/7 monitoring contract. Annex I answers the question "who will hear it, and how quickly?" It matters as much as the sprinklers.
Three transmission levels
| Type | Destination | Typical response | Application |
|---|---|---|---|
| Type A | Direct to the fire service | 5–15 min | High risk: hospitals, hotels, shopping centres, chemical plants |
| Type B | 24/7 monitoring centre, then fire service | 10–30 min | Moderate risk: warehouses, factories, office towers |
| Type C | Local only, plus site personnel | Depends on staff availability | Low risk only, with 24/7 trained staff on site |
Type A — direct fire service connection
In several European countries the sprinkler alarm goes directly to the fire service control room over a dedicated line. The signal from the fire alarm panel is continuously supervised by polling at intervals of no more than 25 hours, and if the signal drops the fire service calls for line maintenance. This infrastructure does not exist in Turkey; automatic connection to the emergency number or a local fire brigade switchboard is not standard practice.
- Two independent transmission paths (wired plus GSM)
- Continuous polling at 25 hour intervals or less
- Line fault alarms transmitted to the fire service
- Insurers generally give the largest discount for Type A
Type B — central monitoring service
A contract is signed between the facility and an alarm receiving centre. Panel signals go to the centre, where an operator watches the screen around the clock. On receiving an alarm the centre:
- Calls the site contact numbers, up to three people in sequence
- Calls the fire service once the fire is confirmed
- Dispatches a response team, where one is contracted
- Produces an incident record and sends it to the client
Private security companies provide this service in Turkey. Monthly fees vary with signal volume, and the service is effectively mandatory for hospitals and shopping centres.
Type C — local alarm only
EN 12845 permits Type C, but on strict conditions: trained fire response personnel on site 24/7 — a watchman is not enough, response training is required; the local alarm audible from every point within the site boundary; a documented procedure for calling the fire service; and monthly drills. In practice a small logistics warehouse or an unstaffed factory at night cannot meet those conditions and must move to Type B. Insurers generally refuse Type C.
Field error — the backup GSM SIM had been cut off
A bank data centre had Type B in place: wired IP as primary, GSM as backup. The annual audit found that the GSM SIM had been disconnected nine months earlier for non-payment. Polling was still answered because the wired path was healthy — but the moment that cable failed the system would have gone blind. The backup path must be checked by an automatic weekly test signal, the SIM billing set to automatic payment with a correct billing address, and the two paths taken from different network operators.
Choosing the transmission technology
| Path type | Advantage | Risk |
|---|---|---|
| PSTN copper | Old, proven, self-powered | Being withdrawn as operators close the network |
| IP (wired) | Fast, cheap, digital | Power failure kills the modem; a UPS is essential |
| GSM | Independent infrastructure, quick to install | SIM supervision, signal strength, jamming |
| RF (radio) | Independent of cabling | Limited coverage, may need a licence |
| Satellite | For very remote or rural sites | Expensive, with latency |
Polling and signal timings
- Type A: maximum 25 hour polling; critical facilities prefer 5 min to 1 hour
- Type B: 25 hours is the upper limit; a good centre recommends hourly polling
- Alarm signal must reach the centre within 90 s
- An unanswered poll must raise a transmission fault alarm within 15 min
- Changeover to the backup path within 90 s of the primary dropping
Signal categories
Annex I is not about a single "fire alarm" signal; at minimum the following are transmitted separately:
- Fire alarm (flow)
- Pump start and pump fault
- Supervised stop valve closed
- Low pressure
- Low water level
- Low temperature (freezing)
- Power failure
- Transmission path fault
- System test — muted and separated from the normal log
What to agree before signing with a monitoring centre
- Response time commitment: who is called, and within how many minutes
- The annual functional test programme
- Incident reporting format (PDF, email, web portal)
- Notification time for a line fault
- Certification to the alarm receiving centre standard, EN 50518
- A backup centre, should the primary one fail
- Annual incident report and statistics
- Data retention and event log handover at contract end
Field error — the operator filtered out the fault alarm
At a shopping centre, a transmission line fault alarmed continuously for six months, so the monitoring centre operator applied a filter and the signal stopped appearing on screen. The real cause was lightning damage to the panel's GSM module, which was never repaired. In month seven a fire broke out, the sprinklers operated, and no signal reached the centre — the path had been dead all along. The centre knew nothing for 22 minutes; the fire service was called by a store manager. This is alarm fatigue in its purest form: operator filters must be prohibited and the underlying fault fixed.
Comparison with NFPA 72
NFPA 72's supervising station chapter is the expanded version of Annex I. NFPA defines three types: central station (a listed ARC), proprietary (operated by the owner) and remote. NFPA sets a maximum polling interval of 4 hours, far tighter than the 25 hours of Annex I. The 90 s alarm transmission limit is the same. NFPA 72 requires a backup path through a digital alarm communicator transmitter. On Turkish projects, international insurers ask for the NFPA 72 polling interval while BYKHY accepts 25 hours.
Link to Turkish regulation
BYKHY's detection and warning provisions require the alarm signal to be continuously monitorable. A 24/7 monitoring contract is checked for hospitals, hotels, shopping centres, high buildings and industrial facilities. Transmission path testing must be documented in the annual functional report, and fire service inspections ask for the monitoring contract, the latest polling report and the monthly test records.
Quick check list
- Transmission level (A, B or C) determined by risk assessment.
- Two independent paths, on different network operators.
- Backup path tested automatically each week.
- Polling interval no more than 25 hours, and no more than an hour on critical sites.
- Monitoring contract with a company certified to EN 50518.
- Response times and call-out list current.
- Monthly functional test recorded.
- A written prohibition on operators filtering fault signals.
Frequently Asked Questions
What are the three alarm transmission levels?
Type A goes direct to the fire service, Type B to a 24/7 monitoring centre which then calls the fire service, and Type C is local alarm only with trained on-site staff.
When is Type C acceptable?
Only with trained fire response personnel on site 24/7, an alarm audible everywhere on site, a documented call-out procedure and monthly drills. Insurers generally refuse it.
How fast must an alarm reach the monitoring centre?
Within 90 s, with changeover to the backup path also inside 90 s if the primary drops. An unanswered poll must raise a fault alarm within 15 min.
Why must the two transmission paths use different operators?
Because a single operator outage takes both paths down at once. The backup path also needs an automatic weekly test signal — a disconnected backup SIM is a classic silent failure.
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Download MEP Calc on the App StoreBS EN 12845:2015+A1:2019 Fixed firefighting systems — Automatic sprinkler systems. EN 12845-2:2024 (CMSA & ESFR sprinkler systems). NFPA 13 Standard for the Installation of Sprinkler Systems. Turkish Regulation on Fire Protection of Buildings (BYKHY). FM Global Property Loss Prevention Data Sheet 2-0.