Short answer: Two. TS EN 12845+A2:2026 Clause I.2 (EN p.156): signals from water flow alarms and/or alarm valves shall be shown as fire alarms (Alarm level A in Table I.1); technical faults such as a power failure, which could prevent the system operating correctly in case of fire, shall be shown as trouble alarms (Alarm level B). There is no third level and no 'Type C'.

Source: TS EN 12845+A2:2026, Annex I (normative) "Transmission of alarms", I.1 and Table I.1 (EN p.155), continuation of Table I.1 and I.2 (EN p.156).

Annex I consists of two clauses: I.1 Functions to be monitored and I.2 Alarm levels. Table I.1 in between shows which clause each alarm in the standard comes from and which type it is.

It is worth starting with an important conceptual correction: A and B are alarm types, not transmission levels. The standard does not define a transmission tier such as "direct to fire brigade" or "local only".

I.1 Functions to be monitored

Clause I.1 (EN p.155):

Table I.1: Type of alarm for transmission

Alarm Clause Alarm type
Water flow alarm 16.1.1 A
Low pressure in town main 9.2 B
Water flow detector in pump room 10.3.2 A
Low level priming tank 10.6.2.4 B
Electric pump set: on demand 10.8.5.1 B
Electric pump set: start failure 10.8.5.1 B
Electric pump set: running 10.8.5.1 A
Electric pump set: power not available 10.8.5.1 B
Diesel pump set: automatic mode off 10.9.2 B
Diesel pump set: start failure 10.9.2 B
Diesel pump set: running 10.9.2 A
Diesel pump set: common fault 10.9.2 B
Trace heating (electrical heating trace) circuits 11.1.2.3 B
Low pressure: pre-action Type A system 11.4.1.2 B
Low pressure: dry pipe and pre-action systems 16.2.3 B

Source: Table I.1, EN p.155.

Continuation of the table (EN p.156):

Alarm Clause Alarm type
Zoned systems: open control valve D.3.7 B
Zoned systems: partially closed control valve D.3.7 B
Zoned systems: partially open subsidiary valve D.3.7 B
Zoned systems: low mains pressure D.3.7 B
Zoned systems: water flow in installation D.3.7 A
Zoned systems: water flow in zone D.3.7 A
Monitored sprinkler systems: partially closed stop valves Annex H B
Monitored sprinkler systems: liquid levels Annex H B
Monitored sprinkler systems: low pressure Annex H B
Monitored sprinkler systems: power failure Annex H B
Monitored sprinkler systems: low temperature in pump room Annex H B

Source: continuation of Table I.1, EN p.156.

The way to read the table comes down to a simple rule: everything related to water flow is Type A, everything related to technical status and faults is Type B.

I.2 Alarm levels

Clause I.2 (EN p.156):

Subject Provision Source
Checkability of the transmission equipment It shall be capable of being checked for continuity of the connection and for continuity of the connection between the alarm switch and the control unit Clause 16.3, EN p.111
Direct connection to the fire brigade The testing procedure should be agreed with the authorities in order to avoid false calls Clause 16.3, EN p.111
Electric pump indications All monitored conditions shall be visually indicated individually in the pump room; pump running and a fault alarm shall also be audibly and visually indicated at a location permanently attended by responsible personnel Clause 10.8.5.2, EN p.65
Diesel pump indications Pump running, start failure, common faults and automatic mode off shall be indicated both locally and at a responsibly manned location by warning lights Clause 10.9.2, EN p.66
Colour at the zoned installation panel Green: each monitored stop valve is in its correct position; amber: a control valve set or subsidiary valve is not fully open, or the static pressure in the trunk main has fallen 0.5 bar or more below normal; red: water is flowing into the installation or into a zone Clause D.3.7, EN p.137
Silencing of alarms Facilities shall be provided at the panel for silencing the audible alarms, but the visual indicators continue to operate until the system is restored to the normal standby condition Clause D.3.7, EN p.137

Subjects not covered by Annex I

Field note

Field note (engineering interpretation, not from the standard): the A/B distinction is more than a priority label, it determines how the panel and the transmission side are separated; routing Type A signals through the same channel as the Type B fault stream causes a genuine fire signal to be lost in the noise of technical faults. Using Table I.1 verbatim as the signal list for a project largely prevents this confusion.

Frequently Asked Questions

How many alarm levels does EN 12845 Annex I define?

Two. TS EN 12845+A2:2026 Clause I.2 (EN p.156): signals from water flow alarms and/or alarm valves shall be shown as fire alarms (Alarm level A in Table I.1); technical faults such as a power failure, which could prevent the system operating correctly in case of fire, shall be shown as trouble alarms (Alarm level B). There is no third level and no 'Type C'.

Where are the alarms transmitted to?

Clause I.1 (EN p.155): alarms shall be connected to an alarm panel in the sprinkler control room or pump room and be transmitted onwards depending on the importance of the alarm. Alarms shall be transmitted to a permanently attended location, on or off the premises. B-Type Alarms (Technical Alarms) may in addition be transmitted to a responsible person in such a way that immediate corrective action can be taken.

What type is the pump running signal?

Table I.1 (EN p.155) lists the 'running' signal for electric and diesel pump sets as Type A. Clause I.2 (EN p.156) allows one flexibility: subject to local conditions, a signal indicating that the sprinkler pump set is running can alternatively be treated as a trouble alarm.

Which signals does Table I.1 list?

Water flow alarm (16.1.1, A); low pressure in town main (9.2, B); water flow detector in pump room (10.3.2, A); low level priming tank (10.6.2.4, B); electric pump set (10.8.5.1: on demand B, start failure B, running A, power not available B); diesel pump set (10.9.2: automatic mode off B, start failure B, running A, common fault B); trace heating circuits (11.1.2.3, B); low pressure (pre-action Type A system 11.4.1.2 B; dry pipe and pre-action systems 16.2.3 B); zoned systems (D.3.7) and monitored sprinkler systems (Annex H).

What applies if there is a direct connection to the fire brigade?

Clause I.1 (EN p.155): if a direct connection to the fire brigade exists, the alarm transmission procedure should be agreed with the authorities. Clause 16.3 (EN p.111) further requires the transmission equipment to be capable of being checked for continuity of the connection and for continuity of the connection between the alarm switch and the control unit.

References

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Standards & References

TS EN 12845+A2:2026 (EN 12845:2015+A2:2026) Fixed firefighting systems — Automatic sprinkler systems — Design, installation and maintenance; TS EN 12845-2:2025 (EN 12845-2:2024) ESFR and CMSA sprinkler systems. Every figure in this article is taken from the published standard text; clause, table and page references are listed under References. General information only, not a substitute for the standard or for a design review.

FS

Fatih Selvi

Mechanical engineer and software developer with field experience in MEP and fire protection, working actively with NFPA, FM Global and BS EN 12845 on site projects.