Common faults·6 minuta čitanja·
Why does the RCD keep tripping?
Five real reasons your residual current device trips, and how to figure out which one without ripping out a single wire.
If your RCD keeps tripping, the device is doing exactly what it’s designed to do — there’s a leakage current somewhere on the circuit. The interesting question is where.
The five suspects
- Wet appliance — the kettle, the washing machine, the boiler. Moisture inside an old heating element is the single most common cause we see on call-outs.
- Damaged cable insulation — usually where a screw or a nail clipped the cable years ago. The leakage stays small until it doesn’t.
- Faulty outlet — a cracked face, condensation, or a poorly seated neutral.
- An RCD that’s end-of-life — they age. Anything older than 15 years is a candidate.
- Cumulative leakage — a dozen small leakages that, summed, push past 30 mA.
How to triage in 5 minutes
- Unplug everything on the affected circuit.
- Reset the RCD. If it holds, the issue is in an appliance — plug them in one by one until it trips.
- If it trips with everything unplugged, the leakage is in the fixed wiring. That’s an electrician job — measure insulation resistance with a 500 V megger.
When to stop and call
If the RCD won’t reset at all, or trips immediately the moment you push it back, stop. Persistent tripping with no load means the leakage is large — likely from damaged wiring near the panel.