Step-by-step guide to understand why your RCD trips at home, find the faulty appliance or circuit, and know when to call an electrician.
The RCD (residual current device, called "diferencial" in Spain) is the switch in your consumer unit with a test button, usually marked with a T. It cuts the power when it detects current leaking somewhere, for example into a person touching a faulty appliance or into water. When it trips, it is almost always doing its job: there is a leak somewhere.
The most common causes at home are an appliance with a damaged heating element (water heater, washing machine, dishwasher, oven), moisture in a socket or an outdoor light after rain, a damaged or crushed cable, and an old or faulty RCD that trips for no real reason.
To find the culprit, start by unplugging every appliance in the house. Then switch the RCD back on. If it stays on, plug the appliances back in one at a time and wait a few seconds with each. When it trips again, the last one you connected is the suspect. Leave it unplugged and call its technical service or an electrician.
If the RCD trips even with everything unplugged, the problem is in the wiring, not in an appliance. Switch off all the circuit breakers (the small switches, one per circuit), switch the RCD on and then turn the breakers back on one by one. The one that makes it trip shows you the circuit with the leak: kitchen, bathrooms, sockets, lighting. Leave that circuit off and use the rest of the house normally until a professional checks it.
Also notice when it trips. If it only happens on rainy days, look for moisture on terraces, utility areas or outdoor sockets. If it always happens at the same time, think about what switches on at that time: a water heater on a time-of-use tariff, scheduled air conditioning or a pool pump.
Never bypass the RCD or hold the switch up by force. It is the protection that prevents electric shocks, and a disabled RCD leaves your home without defence. Do not open sockets or switches with the power on either.
Call an electrician if you smell burning, see black marks on sockets or in the consumer unit, if the RCD trips with everything disconnected, or if you cannot find the cause. Voltusal handles these faults 24/7 in Valencia and the metropolitan area: call or WhatsApp 624 76 18 77.
