Exit sign not illuminated
An illuminated exit sign is dark — it may have lost supply, failed its lamp/LED, or have a faulty driver. A life-safety fitting that must be kept working.
Safety first
Exit and emergency lighting are life-safety systems — never leave one out of service. Isolate before working; this is licensed work and may need certified testing afterwards.
Isolate, lock out / tag out, and prove dead before working unless a live test is specifically required, authorised, and carried out under proper supervision. Always follow local regulations, your site procedures, and the equipment manufacturer's documentation.
Full detail — causes, the why, and common mistakes.
Likely causes
Ranked from most to least likely.
- 1
Lost normal supply to the fitting
Most likelyThe sign's mains supply (often a lighting circuit) is off or tripped, so the maintained lamp is dark.
- 2
Failed lamp / LED
#2The sign's lamp or LED module has failed.
- 3
Failed driver / control gear
#3The driver or internal control gear has failed.
- 4
Failed battery (non-maintained shows in test only)
Least likelyOn some fittings the battery has failed; the sign may only fail under test.
Reports are saved on this device to reflect what you actually find.
Testing sequence
Work through one test at a time. Expected reading and what each result means.
Confirm the fitting's normal supply is present (circuit on, not tripped).
Supply present at the fitting.
Powered but dark — check the lamp/LED and driver.
No supply — restore the circuit (find why if tripped).
View all expected readings at once
Fault-finding flowchart
The same logic as a decision tree.
- 1start
Exit sign not lit
→ step 2 - 2decision
Is normal supply present at the fitting?
Yes→ step 3No→ step 4 - 3decision
Do the lamp/LED and driver test healthy?
Yes→ step 5No→ step 6 - 4result
Restore the circuit (find why if tripped).
- 5result
Run the emergency test; battery/control-gear fault — replace and re-test.
- 6result
Failed lamp/LED or driver — replace.
Common mistakes apprentices make
- Leaving an exit sign dark/out of service.
- Assuming the lamp when the supply is off.
- Not performing the emergency test after repair.
- Not recording the test result.
When to stop & escalate
Emergency/exit lighting work is licensed and often subject to scheduled testing and record-keeping requirements. Keep the system in service and have testing certified as required.
If you're past your competence, authorisation, or the safe limits of the job — stop and hand it on. There's no fault worth getting hurt over.
Related faults
Emergency light fails its discharge test
An emergency fitting works on mains but won't stay lit for the required duration when tested (mains removed) — usually a failed/aged battery, but can be charging or lamp issues.
Emergency light stays on / won't go back to normal
An emergency fitting stays in emergency (battery) mode or its charge/fault LED stays wrong even with normal supply present — pointing at the supply sensing, charging, or the fitting.
A single light not working
One light fitting is dead while the rest of the lights on the circuit work fine — points at the lamp, the fitting, or the switch for that point rather than the whole circuit.
Learn the theory
How the gear and circuits behind this fault actually work.