RCD or "fuses" tripping? What it means and what you can safely check

First: what actually tripped?

In your distribution board, you have two types of "guardians" and it's worth distinguishing them, as they indicate different problems:

• Residual Current Device (RCD, "różnicówka") — a wider module with a TEST button. It reacts to current "escaping" outside the circuit, e.g., due to damaged insulation, moisture, or — most importantly — through the human body. This is a life-saving protection device;
• Overcurrent circuit breaker ("eska", commonly "fuses") — a narrow module with a type designation like B10, B16. It reacts to overload (too many devices at once) or a short circuit.

What you can check yourself

A safe elimination method, without unscrewing anything:

• unplug all devices on the tripping circuit from their sockets;
• switch the protection back on — if it holds, plug in devices one by one until you find the culprit;
• typical suspects for RCD: washing machine and dishwasher (heater), boiler, old household appliances, devices that have come into contact with moisture, outdoor lighting after rain;
• typical suspects for "eska": kettle + oven + microwave on one circuit, electric heater on an extension cord, short circuit in a damaged device cable.

If a single device turned out to be the culprit — send it for service or replace it. The installation did exactly what it was supposed to.

When it's the installation, not the equipment

• RCD trips without any device connected;
• trips after rain or on damp days — a classic symptom of a damp junction box or damaged insulation (more in the guide on moisture in the installation);
• trips randomly, even at night when nothing is running;
• the problem affects several circuits at once or appeared after renovation (a drilled cable).

In such situations, guessing won't help — you need to measure the insulation resistance of the circuits and the parameters of the RCD itself. This is what our diagnosis looks like: measurements instead of guessing, written results, diagnosis price known before the visit.

What not to do under any circumstances

• do not replace the protection with a larger one (e.g., B16 with B25) — the wires in the wall were selected for the smaller one; a larger protection does not "fix" the problem, it only allows the wires to overheat;
• do not bridge or switch off the RCD "because it's inconvenient" — it is the only protection in the consumer unit that reacts to electric shock;
• do not ignore the problem because "it's liveable" — insulation faults do not fix themselves.