All lights in one area out (others fine)
Every light in one part of the house is dead while power points and other lighting still work — points at that lighting circuit's protective device or a shared fault.
Safety first
A tripped protective device is protecting against a fault — don't just keep resetting it. Isolate and prove dead before investigating fittings.
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
Lighting circuit breaker/RCBO tripped
Most likelyThe protective device for that lighting circuit has tripped (overload, short, or earth fault).
- 2
Fault on one fitting taking out the circuit
#2A failed fitting or water ingress can trip the whole circuit's protection.
- 3
Loose connection at a shared junction
#3A loose neutral/active at a junction feeding that area kills everything downstream.
- 4
Switch or controller feeding the area faulty
Least likelyA common switch or controller for the area has failed.
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.
Check the switchboard: has the lighting circuit's breaker/RCBO tripped?
Protective device on; nothing tripped.
Not tripped — trace the shared wiring/switch for that area.
Tripped — find why before resetting (don't just re-trip it).
View all expected readings at once
Fault-finding flowchart
The same logic as a decision tree.
- 1start
All lights one area out
→ step 2 - 2decision
Has the lighting circuit's protective device tripped?
Yes→ step 3No→ step 4 - 3decision
Does isolating a fitting/section let it reset and hold?
Yes→ step 5No→ step 6 - 4result
Not tripped — trace the shared junction/switch for that area.
- 5result
The item that re-trips it is the fault — repair it.
- 6result
Trips with all off — fault is in the fixed wiring.
Common mistakes apprentices make
- Repeatedly resetting a tripping breaker instead of finding the fault.
- Not isolating fittings to localise what's tripping the circuit.
- Overlooking water ingress in an outdoor/bathroom fitting on the circuit.
- Missing a loose neutral at a shared junction.
When to stop & escalate
Fixed-wiring faults and anything causing repeated tripping must be found and repaired by a licensed electrician before re-energising. Never defeat or upsize the protection to stop the tripping.
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
Safety switch (RCD) keeps tripping at the switchboard
The safety switch trips repeatedly — instantly on reset, randomly, or when certain appliances run. It's detecting earth leakage somewhere; the job is to find where.
MCB (circuit breaker) keeps tripping
A circuit breaker trips repeatedly — instantly on reset, or after a load runs for a while — and you need to tell a short from an overload from a faulty breaker.
Lights flickering
One or more lights flicker — constantly, intermittently, or when other appliances run. Common with LEDs and dimmers, but can also signal a loose connection.
Learn the theory
How the gear and circuits behind this fault actually work.