An addressable fire alarm loop is the cable that connects the fire panel to its detectors, call points and sounders. Each device has its own address, so the panel knows exactly which one has raised an alarm.
In this guide, we explain how an addressable fire alarm loop is laid out, why it runs in a circle, what to watch when wiring and how to check it. Always follow the panel manual and the local wiring rules.
What is an addressable fire alarm loop?
The loop starts at a terminal on the fire alarm panel, passes through every device and returns to a second terminal on the same panel. Over this one cable pair, the panel talks to each device and powers it.
Because every device has an address, the panel can show the exact room or point of an alarm. Read our comparison of addressable and conventional systems to see why this matters.
Why the addressable fire alarm loop runs in a circle
The loop returns to the panel for safety. If the cable is cut at one point, the panel can still reach every device from both ends. As a result, a single break does not take devices out of service.
Short-circuits are the other danger. A short can stop part of the loop. To limit its effect, designers fit short-circuit isolators, which cut off only the faulty section. Your panel manual states how many devices can sit between isolators.
Wiring an addressable fire alarm loop: key rules
Follow these rules, and always check them against the panel manual.
- Use the cable type the panel maker and the local code ask for, usually a fire-resistant, screened cable.
- Keep the loop as one continuous path out and back, and avoid unplanned branches.
- Respect the maximum number of devices and the maximum cable length for your panel.
- Do not mix loop cable with power or mains cables.
- Keep the screen continuous and connect it as the manual shows.
- Label every device and write its address on the drawing.
How to test an addressable fire alarm loop
Testing is quick when the drawing is clear.
- Check the cable for continuity and insulation before the devices are connected.
- Connect the devices and let the panel learn them.
- Compare the list of devices on the panel with the drawing.
- Operate each device to check that the right address and text appear.
- Open the loop at one point to confirm that all devices still answer from both ends.
What else can sit on a loop?
Detectors, call points, sounders and beacons are the usual devices. Also, input and output modules can add extra signals, as explained in our guide to input and output modules. Some aspirating detectors also report to the loop. On a ModuLaser network, an addressable panel interface card plugs into the display module, so every detector reports to the Excellence panel on the loop.
Products for addressable loops
The Excellence Series offers addressable control panels and addressable sounders and beacons. Also, see the addressable fire detection systems page and our guide on fire alarm control panels. The ModuLaser connects through its APIC card.
Key takeaways
- An addressable loop is one cable pair that links the panel with every device, out and back.
- The return path means a single cable break does not disable devices.
- Isolators limit the effect of a short circuit to one section.
- Always follow the panel manual for cable type, limits and testing.
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Why does an addressable loop return to the panel?
So that a single cable break does not cut off devices. The panel can reach every device from both ends of the loop.
What is a loop isolator?
A short-circuit isolator cuts off the faulty section of the loop, so the rest keeps working.
How many devices can I put on one loop?
It depends on the panel and the devices. Check the manual of your panel for the limit.
Can I add a branch to a loop?
Only when the panel manual allows it and within its limits. Unplanned branches can reduce the safety of the loop.
Read the whole picture in Addressable Fire Alarm vs Conventional and plan the system with our guide on fire alarm control panels.