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 first
An appliance that trips the protection likely has a fault to earth — a shock risk. Stop using it. Don't bypass the safety switch to keep it running.
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
Earth fault inside the appliance
Most likelyDamaged insulation, a failed element or motor winding leaking to earth trips the safety switch on switch-on.
- 2
Short circuit in the appliance or its lead
#2A short trips the breaker instantly.
- 3
Damaged flex / plug
#3A damaged lead or plug shorts or leaks to earth.
- 4
High switch-on leakage (filters)
Least likelySome equipment has a switch-on earth-current transient that trips a sensitive safety switch.
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 it's that appliance: it trips reliably only when that item is plugged in/switched on.
Tripping clearly tied to that one appliance.
Confirmed — remove the appliance from use and have it checked.
If other things trip it too, treat as a circuit/safety-switch fault.
View all expected readings at once
Fault-finding flowchart
The same logic as a decision tree.
- 1start
Appliance trips power
→ step 2 - 2decision
Does only that appliance trip it (in isolation)?
Yes→ step 3No→ step 4 - 3decision
Is the lead/plug undamaged?
Yes→ step 5No→ step 6 - 4result
Other things trip it too — treat as a circuit/safety-switch fault.
- 5result
Appliance needs testing/repair — remove from use.
- 6result
Damaged lead/plug — appliance unsafe; repair/replace.
Common mistakes apprentices make
- Continuing to use an appliance that trips the safety switch.
- Bypassing or 'strapping out' the protection to keep using it.
- Not isolating the appliance to confirm it's the culprit.
- Assuming nuisance when there's a real earth fault.
When to stop & escalate
An appliance with a suspected earth fault should be tested/repaired by a competent person or replaced — never run on defeated protection. If the wiring (not the appliance) is at fault, that's licensed electrical work.
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.
RCD trips the moment a specific load is switched on
The RCD is fine until a particular appliance/circuit is switched on, then it trips immediately — clearly pointing at that load or its switch-on behaviour.
Power point burnt, melted, or smells hot
A GPO is discoloured, melted, or gives off a burning smell — a serious fire-risk fault from arcing/overheating at the outlet, usually from a poor plug fit or overload.