Wireless (Radio) Fire Alarm Systems
Wireless fire detection has moved from a niche solution to a mainstream option, especially in buildings where running cable is difficult, disruptive or simply not allowed. Understanding how these systems work — and what makes them reliable or unreliable — helps you survey, commission and maintain them properly. This guide covers the principles, the survey, and the maintenance discipline that wireless systems demand.
The core safety functions are identical to a wired system. What changes is the communication path and, with it, the things you have to get right.
Who this is for
This is for competent fire alarm engineers surveying, commissioning or maintaining wireless or hybrid systems. The experience level assumed is competent engineer. Use it for the principles; use the product manufacturer's data and the current standards for design, survey criteria and battery management.
How wireless systems work
Instead of detection cabling, wireless systems link devices to the panel by radio, usually through radio expanders that bridge to a wired panel, or as fully wireless arrangements. Devices are battery powered and communicate over a monitored radio protocol, so a lost link or a low battery is reported as a fault rather than passing unnoticed. Components using radio links are covered by BS EN 54-25, and the overall system still follows BS 5839-1. The alarm, detection and interface behaviour that occupants rely on is the same as a wired system.
Where wireless suits
Wireless comes into its own where cabling is impractical: heritage and listed buildings where disturbance must be minimised, occupied premises where disruption matters, buildings with solid or awkward construction, and temporary or phased arrangements. It can also speed installation. None of that removes the need for proper design — it simply changes the delivery method.
The radio survey
The single most important activity for a reliable wireless system is the radio survey. It checks the signal strength and quality between each proposed device position and its expander or panel, identifies interference and the attenuation caused by walls, floors and contents, and confirms there is enough signal margin for the link to stay dependable over time. Positions with marginal signal are moved, or expanders added, before installation is fixed. The survey results should be recorded and revisited if the building or its contents change significantly, since new partitions or stored goods can degrade a previously good link.
Battery and signal maintenance
Every wireless device has its own battery, so a large system has a lot of batteries to manage. The system monitors and reports low batteries, but relying on fault reports alone leads to a wave of callouts as batteries reach end of life together. Planned replacement to the manufacturer's stated battery life, and attention to signal-quality trends during service, keep the system healthy. Battery types, life and replacement intervals all come from the manufacturer's data.
Common issues on site
From field experience, the recurring problems are marginal signal positions accepted at install, batteries left until they fault, and building changes — new walls, large metal racking, altered layouts — that quietly weaken radio links. Recording signal margins at commissioning gives you a baseline to compare against during service, which is the best early warning of a link degrading.
When not to rely on this alone
When not to use this article: do not use it to set survey acceptance criteria, choose devices, or plan battery intervals for a specific product. Those come from the manufacturer's documentation and the current standards. Radio performance and battery life vary between products and must be taken from the relevant data.
Relevant standards
Wireless components are covered by BS EN 54-25, a product standard, while the system as a whole follows BS 5839-1, a code of practice. The legal duty to provide suitable detection where necessary in most non-domestic premises sits under the Regulatory Reform (Fire Safety) Order 2005. Distinguish the legal duty from the recommended methods when advising a client, and work to the current editions and the manufacturer's data.
Professional disclaimer
This is an educational and workflow resource for competent engineers and does not replace the manufacturer's documentation, the current British Standards, the site fire strategy, or competent design and survey judgement. Verify survey criteria, device selection and maintenance against current documentation.
Related documentation
Use this with the wireless product manufacturer's design and commissioning guide, the current BS 5839-1 and BS EN 54-25, and the site design. Record survey signal margins and battery details in the commissioning and service documentation.