The main difference between an addressable and a conventional fire alarm system is how precisely the control panel can tell you where the fire is. A conventional system groups detectors and call points into zones and shows which zone is in alarm. An addressable system gives every device its own address on a wiring loop, so the panel shows the exact device and location. Conventional systems are simpler and usually cheaper for small buildings; addressable systems suit larger or more complex sites. This guide explains how each works, the two-wire option in between, and how to choose a panel.
How a conventional fire alarm system works
In a conventional system, detectors and call points are wired on radial circuits called zones, and sounders are wired on separate sounder circuits. When a device in a zone operates, the panel shows that zone in alarm. To find the actual device, someone has to go to that zone and look for the detector with its LED lit.
Because the panel only knows which zone is in alarm, zoning matters. BS 5839-1 limits the size of a zone, for example to a floor area of no more than 2,000 m² and a search distance of no more than 60 m, and a zone should normally cover only one storey. Your system designer will set out the zones for the building.
Conventional panels are typically available with 2, 4 or 8 zones. Examples include the FireClass Essential 4 zone panel, which supports up to 32 devices per zone and is approved to EN 54-2 and EN 54-4, and the C-TEC CFP708-4 8 zone conventional panel.
Two-wire conventional systems
A two-wire (or twin-wire) system is a variation of conventional. Detectors, call points, sounders and visual alarm devices are all connected on the same pair of wires on each zone, which can save cable and installation time. The panel uses different voltage levels for normal and alarm states. Two-wire devices must be compatible with the panel; the C-TEC CFP AlarmSense 4 zone two-wire panel, for example, is designed for Apollo AlarmSense devices.
How an addressable fire alarm system works
In an addressable system, devices are wired on a loop that starts and finishes at the panel. Each detector, call point, sounder and interface has a unique address, so the panel can display messages such as "Smoke detector, first floor kitchen". Because the loop is wired in a ring, a single break in the cable does not stop devices communicating, and short-circuit isolators limit how many devices a single short circuit can take out.
Most modern addressable systems are analogue addressable: detectors report a value back to the panel, which can warn of a dirty detector before it causes a false alarm and supports different sensitivity modes at different times of day.
Addressable devices use a manufacturer's communication protocol, and the panel must support it. The C-TEC XFP single loop, 16 zone panel works with Apollo XP95 and Discovery devices, while the Advanced MxPro 5 MX-5101 supports Apollo XP95/Discovery and Hochiki ESP protocols.
Addressable vs conventional: side by side
| Conventional | Addressable | |
|---|---|---|
| Location shown | Zone | Individual device, with text description |
| Wiring | Radial zone circuits plus sounder circuits | Loops shared by detectors, call points, sounders and interfaces |
| Typical buildings | Small shops, offices, small schools and similar | Larger or multi-storey buildings, hospitals, hotels, sites with complex cause-and-effect |
| Equipment cost | Lower | Higher per device |
| False alarm management | Basic | Detector monitoring, drift compensation and day/night modes |
| Device compatibility | Broad, if the panel is compatible | Must match the panel's protocol |
| Controlling other equipment | Limited relay outputs | Interface modules on the loop for door holders, plant shutdown, lifts and more |
Which should you choose?
There is no single size at which you must switch from conventional to addressable. The decision is made by the system designer, based on the size and layout of the building, the zoning BS 5839-1 requires, how quickly the fire service and staff need to find the fire, and how much control of other equipment is needed.
- Choose conventional for small, simple buildings where a few zones give enough information and budget is tight.
- Choose two-wire conventional when you want conventional simplicity with less cabling.
- Choose addressable for larger buildings, where finding the exact device saves time, where false alarms are a concern, or where the system needs to control doors, plant or other systems through interface modules and isolators.
Whatever you choose, use a panel certified to EN 54-2 (control and indicating equipment) and EN 54-4 (power supply), and devices the manufacturer lists as compatible. Browse our full range of fire alarm panels.
Frequently asked questions
Can I connect addressable detectors to a conventional panel?
No. Addressable devices need a panel that supports their protocol. Some conventional detectors can be used on addressable loops through a zone interface module, if the manufacturer approves it.
Is an addressable system more reliable?
Both are reliable when designed and maintained correctly. Addressable loops are more tolerant of single cable faults and give more information, which helps maintenance.
Can I upgrade a conventional system to addressable?
Usually this means a new panel and devices. Existing cable can sometimes be reused if it is suitable, but this must be checked by the installer.
Which is cheaper?
Conventional equipment usually costs less for small systems. On larger sites, addressable systems can reduce cabling and maintenance time.
This guide is general information; system design should follow BS 5839-1 and the advice of a competent fire alarm designer.