> For the complete documentation index, see [llms.txt](https://docs.accessia.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.accessia.com/hardware/ai-security-hub-hub-v1/inputs-and-outputs/fire-alarm-interface.md).

# Fire alarm interface

* The Hub includes a **FIRE IN** input that can be connected to an isolated relay driven by a fire alarm system. Do not connect this input to a power supply
* Configure the sense of the relay (normally open or normally closed) using the slide switch on the Hub (a red indicator lights up when the fire condition is indicated). A loop resistance greater than 500 kOhms will be interpreted as Open and a loop resistance less than 500 Ohms will be interpreted as Closed
* Use a shielded cable and connect the shield to earth using the labeled earth post inside the enclosure
* When the FAI is used, you can configure each lock to unlock in response to the fire condition
  * For each lock, set the corresponding fire override slide switch to on. Note that you must set the power-to-lock/power-to-open switch correctly to ensure that the lock will unlock during a fire condition
* When using the FAI feature, the installation must be tested and approved by the relevant fire authority to ensure that the behavior results in a system that is safe
* For any power-to-open locks, do not rely on this feature for safety, as failures elsewhere in the system can result in power loss to the lock
* This feature is not a substitute for mechanical overrides or break-glass disconnects at the exit door to allow for safe exit from the building in the event of an emergency