An addressable fire alarm system connects every detector, call point, module and sounder to the control panel on a shared cable called a loop. Each device has its own address, so the panel knows exactly which device is in alarm or in fault. This guide explains how a typical addressable fire alarm wiring diagram is built, which rules apply under the EN 54 standards, and where to find the TeledataOne typical connection drawings.
It is written for consultants, designers and installers. It does not replace the manufacturer’s manuals, the project specification or the fire code that applies in your country.
1. The building blocks
A typical addressable system has five parts:
- Control and indicating equipment (CIE): the fire alarm control panel, certified to EN 54-2. It powers the loops, reads every device and drives the outputs.
- Power supply: certified to EN 54-4, with mains supply and standby batteries.
- Loops: the cables that leave the panel, run through the building and carry both power and data to the devices.
- Loop devices: detectors, manual call points, sounders and beacons, input and output modules.
- Interfaces: connections to other systems, such as door holders, ventilation, lifts, sprinklers or a building management system.
EN 54-13 covers the compatibility of the whole system: it checks that panel, power supply and field devices work together as certified. For this reason, consultants usually ask that the devices on the loop come from the same manufacturer as the panel, or that compatibility is documented.
2. Loop wiring: Class A and Class B
Most specifications describe two ways to wire the circuit:
- Class A (closed loop): the cable leaves the panel, passes through all the devices and returns to the panel on a second terminal. The panel can reach every device from both ends. If the cable is cut in one place, all devices keep working.
- Class B (open line or spur): the cable leaves the panel and ends at the last device. A single cut disconnects every device after the break.
The terms “Class A” and “Class B” come from American practice (NFPA 72), but they appear in many international tenders. In European practice the closed loop is the standard design for addressable systems, and short spurs are allowed only where the local code permits them.
Good practice for the loop:
- run the outgoing and return cables on different routes, so that one fire or one mechanical damage cannot cut both;
- use the cable type and maximum length given in the manufacturer’s wiring specification, and fire-resistant cable where the local code asks for it;
- label both ends of the loop in the panel and keep the polarity the same on the whole circuit.
3. Short-circuit isolators
A cut cable is not the only risk: a short circuit on the loop can take down every device on it. To limit this, the loop is divided into segments with short-circuit isolators.
When a short circuit happens, the isolators on each side of the fault open. The panel feeds the rest of the loop from both ends, and only the devices between the two isolators are lost. The panel reports a fault, so the installer knows where to look.
Rules to check in your design:
- the maximum number of devices between two isolators. This is set by EN 54-2 and by the national design code, and is typically 32 devices;
- an isolator at the boundary of each fire zone, so a single fault does not affect more than one zone;
- an isolator near the panel on both the outgoing and the return side.
Isolators can be separate devices, or they can be built into the detector base or the module. On TeledataOne, the OneModule and OneMicrom multi-modules have a built-in short-circuit isolator (source: OneModules landing page). See the OneModules range.
4. Loop devices
Each device on the loop takes an address and some current from the loop:
- Detectors (smoke, heat, multi-sensor) are fitted on bases wired in and out on the loop.
- Manual call points are wired the same way, usually near exits.
- Sounders and beacons (EN 54-3 and EN 54-23) can be loop-powered, which saves a separate sounder circuit. Check the current draw: the total load of all devices must stay within what the loop can supply.
- Sounder bases combine a detector and a sounder in one point.
When you plan the loop, check three numbers: how many addresses it accepts, its total current, and its cable length. A loop calculation, done with the manufacturer’s data, tells you if the design works before installation.
5. Input and output modules
Modules connect the loop to everything that is not a detector:
- Input modules read a contact from another system, for example a sprinkler flow switch, a gas detection panel or a door contact.
- Output modules drive a relay or a supervised output, for example to release door holders, stop ventilation, call lifts to the ground floor or start a conventional sounder circuit.
- Modules with a 230 V output or an external supply are used for loads that the loop cannot power.
In the wiring diagram, show for each module the loop address, the field device it controls or reads, the cable type and, for supervised outputs, the end-of-line component.
6. Power supply to EN 54-4
The panel and any remote power supplies must comply with EN 54-4. In practice:
- a dedicated mains circuit, protected and clearly labelled;
- standby batteries sized for the standby time and the alarm time that your local code asks for;
- a battery calculation that includes the panel, all loop devices, sounders, beacons and modules in alarm.
Remote power supplies must also be monitored by the panel.
7. Networks of panels
Large sites use several panels connected in a network. Each panel manages its own loops, and any panel can show events from the whole site. TeledataOne panels are available from 1 to 9 loops, with up to 240 devices per loop, and they can be networked up to 128 panels (source: TeledataOne panel pages). See the TeledataOne control panel.
8. Typical connections
A general diagram shows the logic. On site, installers need the exact terminals. For this reason, TeledataOne product pages include downloadable documents, with typical connection drawings (PDF) where available:
- panel: loop terminals (out and return), power supply and batteries, relay outputs, network connection;
- loop devices: detector bases, call points, sounders and beacons;
- modules: input, output and mixed modules, with field wiring and end-of-line components.
Start from the addressable fire detection range, open the product, and download the typical connection PDF together with the datasheet and the manual. If you cannot find a drawing, or you need one for a special project, our technical team can help.
Need help with your design?
Founded in 1977 as a hardware and software house, Teledata has designed and manufactured EN 54 fire detection systems in Italy since 2003, and works with distributors and installers in more than 30 countries. If you are preparing an addressable fire alarm wiring diagram for a project, contact us: we can check the loop layout, the isolator positions and the power supply calculation with you.
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