Outdoor / garden light not working
An outdoor or garden light is out — could be the lamp, a sensor/timer, weatherproofing/water ingress, or the supply.
Safety first
Isolate and prove dead before working. Outdoor fittings must be weatherproof; check seals when working on them.
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
Failed lamp / fitting
Most likelyThe globe/LED or integrated fitting has failed.
- 2
Sensor / timer / daylight setting
#2A PIR/timer/daylight control isn't activating the light (or is set to night-only).
- 3
Water ingress / failed weatherproofing
#3Moisture in the fitting causes failure or tripping.
- 4
Supply / switch fault
Least likelyA switch, transformer (for low-voltage garden lighting), or circuit fault.
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.
Try a known-good lamp and check any sensor/timer/daylight settings.
Works with a good lamp and correct settings.
It was the lamp/settings — done.
Still out — check weatherproofing/water and supply.
View all expected readings at once
Fault-finding flowchart
The same logic as a decision tree.
- 1start
Outdoor light out
→ step 2 - 2decision
Does a known-good lamp + correct settings work?
Yes→ step 3No→ step 4 - 3result
It was the lamp/settings — done.
- 4decision
Is the fitting dry and supply (transformer) present?
Yes→ step 5No→ step 6 - 5result
Dry fitting but dead with supply — replace the fitting.
- 6result
Water ingress or no supply/transformer fault — rectify.
Common mistakes apprentices make
- Not checking a sensor/daylight setting that blocks daytime testing.
- Ignoring water ingress in the fitting.
- Overlooking a failed low-voltage transformer for garden lighting.
- Working live on an outdoor fitting.
When to stop & escalate
Outdoor lighting work is licensed electrical with weatherproof, suitable equipment. Low-voltage garden lighting transformers/wiring should also be checked by a licensed person.
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
Motion-sensor light not working correctly
A sensor (PIR) light won't come on, stays on permanently, or triggers at the wrong times — common on eaves, garages, and entries.
Outdoor power point not working
An outdoor GPO is dead — often after rain — pointing at a tripped safety switch from moisture, a weatherproofing failure, or the outlet/run.
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.