Do not remove, isolate or replace fire alarm devices without controlling the impairment
Confirm the affected area, record the panel information and follow the site fire procedure. Device testing, addressing and loop fault finding should be completed by a competent fire-alarm engineer using compatible equipment.
MOST LIKELY CAUSES
Start with the device and panel information
Symptom variations Match the exact device, address and loop behaviour. ⌄
- No reply or missing device message
- One address absent
- Block of addresses absent
- Fault after device replacement
- Loop fault appears with missing devices
Safe first checks Checks for authorised site staff before engineering work. ⌄
- Record the exact loop, address, zone and device text.
- Check whether the device is physically present and visibly undamaged.
- Review recent decorating, ceiling or electrical work.
- Check whether one device or a group of devices is affected.
- Do not leave a detector or call point removed or disabled without formal controls.
Step 1 — Record the exact device and fault text Follow the site fire procedure and do not leave devices isolated without formal impairment controls. ⌄
Note the loop, address, location and whether adjacent devices are also missing.
Step 2 — Check whether the device is physically present Follow the site fire procedure and do not leave devices isolated without formal impairment controls. ⌄
Confirm it is fitted and has not been replaced with a different type.
Step 3 — Review recent works Follow the site fire procedure and do not leave devices isolated without formal impairment controls. ⌄
Look for cable damage, isolations or address changes.
What the indication usually means How this device or loop condition develops. ⌄
A non-responding device may be missing, incorrectly addressed, disconnected, isolated by a short-circuit isolator or affected by loop communication problems.
Engineer diagnostic sequence Competent-person checks after the site information has been captured. ⌄
- Poll the device with panel diagnostics or manufacturer tools.
- Check continuity from both loop directions.
- Inspect isolator LEDs and section boundaries.
- Verify device protocol and configuration.
- Substitute with a known-good compatible device where authorised.
Information and equipment needed Useful items for accurate fault finding. ⌄
- Panel make, model and protocol
- Loop and device schedule
- As-fitted drawings and zone plan
- Manufacturer programming or test tools
- Approved detector and call-point test equipment
Parts that may be involved Components commonly associated with this fault. ⌄
- Compatible detector or module
- Address programmer
- Short-circuit isolator
- Loop cable
- Replacement base or terminals
When immediate action is required Conditions that should trigger escalation or an impairment plan. ⌄
- Several devices or a complete loop section are missing.
- The affected area has no suitable detection or manual alarm coverage.
- A call point cannot be restored.
- The fault follows water ingress, fire, impact or cable damage.
- The device type, address or location cannot be confirmed.
- The system cannot be returned to normal after repair.
Frequently asked questions Common detector and device questions. ⌄
Can a dirty detector simply be blown out?
Only where the manufacturer specifically permits an approved cleaning method. Uncontrolled compressed air can damage the chamber or drive contamination further inside.
Can a detector be swapped with another one?
Only with a compatible device and with the addressing method, configuration and test requirements understood.
Does one missing device matter?
Yes. It may leave part of the building without the intended detection or control function.