First: which thing is tripping?
Open the consumer unit cover and look at what has switched off. A single small switch (an MCB) protects one circuit — the kitchen sockets, say. A wider switch with a T or Test button (an RCD) protects a group of circuits against earth faults and usually takes several MCBs down with it. Newer boards have RCBOs, which do both jobs for one circuit each. What has tripped narrows the cause a lot.
The seven causes we find most often
- A faulty appliance. By far the most common. Kettles, washing machines, dishwashers, tumble dryers, immersion heaters and old fridges all develop earth faults. If the RCD trips when a particular appliance runs, unplug it and see if the tripping stops.
- Water where it should not be. Outdoor sockets, garden lights, shed supplies and bathroom fans trip RCDs when rain gets in. If it trips when it rains, this is almost certainly it.
- An overloaded circuit. An MCB (not RCD) that trips when the electric heater, hairdryer and tumble dryer are all on together is doing exactly what it should. The fix is a dedicated circuit, not a bigger breaker.
- A damaged cable. Nails through cables after shelving or flooring work, rodent damage in lofts, or a cable crushed under a floorboard.
- A failed or worn breaker. Breakers do wear out, and the one in the photo above had overheated at the terminal until it burnt. This one needs an electrician.
- A borrowed neutral or DIY alteration. Common in older Leeds terraces where lighting circuits have been extended over the years. The RCD trips when a particular light switch is used.
- Deteriorating insulation in old wiring. The RCD trips at random, more often in damp weather, with nothing obvious plugged in. Usually a sign that a circuit — or the house — is due for rewiring.
What you can safely try
Unplug everything on the affected circuit, reset the breaker once, and plug things back in one at a time. If it holds until a particular appliance goes in, you have found it. If it trips immediately with nothing plugged in, the fault is in the fixed wiring and there is nothing more to try. Do not keep resetting a breaker that trips straight away, and do not replace a breaker with a bigger one — that removes the protection that is keeping the cable from overheating.
When to call
Call an electrician if the breaker trips with nothing plugged in, if you smell burning or see scorching at the board, if a socket or switch is warm, or if you simply cannot find the cause. Our emergency electrician service attends across Leeds; fault finding starts from £75 for the first hour and most tripping faults are found within it. If the board itself is old, with no RCD protection or a plastic enclosure, the visit is a good moment to talk about a consumer unit replacement.
Common questions
Is it dangerous if a breaker keeps tripping?
The tripping itself is the protection working. The danger is what it is protecting you from — an earth fault, an overheating cable, water in a fitting. It should be investigated, not ignored or bypassed.
Why does my RCD trip when it rains?
Almost always water getting into an outdoor socket, light, shed supply or the junction box for one of them. Isolate the outdoor circuit if you can and have it checked.