A circuit breaker keeps tripping (domestic)
One circuit breaker keeps tripping — instantly on reset or after a load runs — and you need to tell an overload from a short or a faulty appliance.
Safety first
The breaker is protecting against a fault — don't keep resetting it or fit a bigger one. Isolate and investigate.
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.
Apprentice mode
Full walk-through — the why, what readings mean, mistakes & safety.
Likely causes
Ranked from most to least likely.
- 1
Circuit overloaded (too much load)
Most likelyToo many high-draw appliances on one circuit trip it after running a while (thermal).
- 2
Faulty appliance shorting/overdrawing
#2A faulty appliance draws excess current or shorts, tripping the breaker.
- 3
Short circuit in the wiring
#3A short (e.g. nail through a cable, damaged fitting) trips it instantly.
- 4
Wrong breaker / faulty breaker
Least likelyAn under-rated or faulty breaker trips below its expected point.
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.
On the tools? Job Mode shows one test at a time with thumb-sized buttons — your place and readings carry straight over.
Enter Job ModeNote when it trips: instantly on reset (short), or after a load runs (overload).
A pattern separating short from overload.
Instant → short; delayed → overload/appliance. Proceed accordingly.
Random → suspect an intermittent appliance or breaker.
View all expected readings at once
Fault-finding flowchart
The same logic as a decision tree.
- 1start
Breaker keeps tripping
→ step 2 - 2decision
Does it trip instantly on reset (vs after a load runs)?
Yes→ step 3No→ step 4 - 3decision
Is the circuit free of shorts/earth faults?
Yes→ step 5No→ step 6 - 4decision
Does removing high loads/appliances stop the tripping?
Yes→ step 7No→ step 8 - 5result
Suspect a faulty breaker — replace and re-test.
- 6result
Short/earth fault — locate and repair before re-energising.
- 7result
Overload or faulty appliance — rebalance / repair.
- 8result
Trips with all unplugged — fault in the fixed wiring.
Common mistakes apprentices make
- Resetting repeatedly into a short.
- Fitting a larger breaker to stop the tripping (defeats protection).
- Not distinguishing instant (short) from delayed (overload) trips.
- Overlooking a faulty appliance as the cause.
When to stop & escalate
A short/earth fault in the wiring is licensed electrical work and must be repaired before re-energising. Never upsize a breaker to suit the load without a circuit assessment.
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.
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Related faults
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.
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.
Half the power points in the house not working
A group of outlets across several rooms is dead together while lights and other GPOs work — points at one power circuit's protection or a shared upstream fault.
Learn the theory
How the gear and circuits behind this fault actually work.