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Apollo XP95 & Discovery
Fault Finding & Support Hub
About Apollo
Apollo Fire Detectors is the UK's leading manufacturer of addressable fire detection devices. The XP95 protocol has been an industry standard for decades, while Discovery represents the next generation with enhanced diagnostics. Apollo devices are found in the majority of UK commercial and industrial addressable fire alarm systems.
Panel Models Covered
Common Apollo Faults
The most frequently encountered fault types on Apollo XP95 & Discovery systems. Always verify against current manufacturer documentation.
Loop open circuit
Wiring break or failed device on the loop. Check for physical damage, test with fault isolators to locate segment, verify device connections.
Loop short circuit
Insulation failure or cable damage causing line-to-line short. Fault isolators activate to isolate the affected segment.
Device removed / missing
Device base no longer receiving a response from the head. Check head seating, base contacts and loop continuity.
Analogue value low
Device sensitivity below threshold — possible contamination, aging or incorrect sensitivity setting. Clean or replace detector.
Analogue value high
Detector reading elevated — possible contamination, insect ingress, or pre-alarm condition. Inspect and clean detector head.
Communications fault
Panel unable to communicate with device. Check device address, loop wiring integrity and isolator status.
Dirty / contaminated detector
Optical chamber contaminated. Clean with approved method or replace if cleaning does not restore normal analogue value.
Output fault
Sounder, beacon or relay output not responding. Check output wiring, device condition, and output card functionality.
PSU fault
Power supply voltage or current outside tolerance. Check mains supply, battery condition and PSU output.
Zone fault
Conventional zone fault — check end-of-line resistor, zone wiring and device connections within the zone.
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Safety Notice
Always verify fault information against current Apollo manufacturer documentation and technical bulletins. Fault descriptions on this page are guidance for qualified engineers only. Do not carry out work that could impair life-safety systems without proper assessment. Users remain responsible for all on-site decisions.
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