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.
Safety first
The safety switch trips because of earth leakage — a real shock risk. Never bypass it or replace it with a non-safety device. Find the leakage.
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
A faulty appliance leaking to earth
Most likelyA specific appliance (kettle, heater, washing machine, fridge) with an earth fault trips the safety switch, often when it runs/heats.
- 2
Water ingress / moisture on a circuit
#2Moisture in outdoor outlets, bathroom fittings, or damp areas creates leakage.
- 3
Wiring insulation fault (incl. neutral-earth)
#3Damaged cable insulation or a neutral-earth fault in the fixed wiring trips it.
- 4
Accumulated leakage from many devices
#4Lots of electronics on one safety switch can add up near its threshold and trip on a transient.
- 5
Faulty safety switch
Least likelyLess common — the device itself has become over-sensitive or faulty.
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 the pattern: instant on reset, random, or only when a specific appliance runs?
A pattern pointing at an appliance, a circuit, or wiring.
A clear trigger narrows it to one appliance/circuit.
If it trips with everything off, suspect wiring or the device.
View all expected readings at once
Fault-finding flowchart
The same logic as a decision tree.
- 1start
Safety switch keeps tripping
→ step 2 - 2decision
Does a specific appliance/circuit trigger it?
Yes→ step 3No→ step 4 - 3result
Isolate that appliance/circuit and rectify the leakage.
- 4decision
With everything off, does it still trip?
Yes→ step 5No→ step 6 - 5result
Wiring/insulation fault or faulty device — have it tested and rectified.
- 6result
Reintroduce loads one at a time; consider splitting circuits.
Common mistakes apprentices make
- Bypassing or replacing the safety switch with a non-safety device.
- Not isolating circuits/appliances to localise the leakage.
- Forgetting neutral-earth faults and water ingress.
- Blaming the safety switch before proving the leakage isn't real.
When to stop & escalate
Wiring/insulation faults and safety-switch testing are licensed electrical work. Never remove earth-leakage protection as a 'fix'. A confirmed faulty appliance should be repaired or taken out of use.
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
RCD / RCBO keeps tripping
An RCD or RCBO trips repeatedly — immediately on reset, randomly during the day, or only when certain equipment runs. The earth-leakage protection is doing its job; something is leaking.
An appliance trips the power the moment it's plugged in or switched on
Plugging in or switching on a particular appliance instantly trips the safety switch or breaker — strongly suggesting an earth fault or short in that appliance.
Safety switch won't reset
The safety switch won't stay up when you try to reset it — power can't be restored because a fault is still present (or the device/wiring is at fault).
Learn the theory
How the gear and circuits behind this fault actually work.