Electricity that keeps tripping is almost always your fuse board doing its job and protecting you from a fault. The usual causes are a faulty appliance, water getting into a socket or fitting, an overloaded circuit, or an RCD that is on its last legs. You can safely narrow it down yourself by unplugging and resetting one circuit at a time. If it keeps going, it needs an electrician.
What is actually tripping, the RCD or an MCB?
It helps to know which switch has gone, because they protect against different things.
- An MCB (the small individual switch on one circuit) trips when that circuit draws too much current, usually an overload or a short circuit. When it goes, you lose just that one circuit, say the kitchen sockets or the upstairs lights.
- An RCD (often a bigger switch with a “T” or “Test” button) trips when it senses current leaking to earth, the kind of fault that can give you a shock. On many older boards a single RCD covers half the house, so when it goes you can lose lights, sockets and the freezer all at once.
- An RCBO combines both jobs in one device per circuit, which is why a modern board only knocks out the one affected circuit instead of half the house.
Knowing whether you lost one circuit or a whole bank tells you a lot about what to look for.
What are the most common causes?
In the vast majority of homes it comes down to one of these:
- A faulty appliance. A failing kettle element, a tired washing machine, an old immersion heater or even a cheap phone charger can leak to earth and trip an RCD. This is the single most common cause.
- Water getting in. Moisture in an outdoor socket, a leaking shower, a roof leak finding a light fitting, or a flooded garden socket will trip the protection every time. Tripping that started after rain is a big clue.
- An overloaded circuit. Too much plugged into one ring, or a high-load appliance like a heater or tumble dryer pushing a borderline circuit over the edge, trips an MCB.
- A borderline or failing RCD. RCDs do wear out. An old one can become oversensitive and start nuisance-tripping for no obvious reason, or trip on the small, normal leakage that several appliances add up to.
- A genuine wiring fault. Damaged cable, a loose connection, or a nail through a cable from a recent shelf or picture can all cause it.
How can I find the cause myself safely?
You can do some safe detective work before you call anyone, no tools and nothing inside the board needed.
- Unplug everything on the affected circuit, or everything in the house if the main RCD keeps going.
- Reset the tripped switch. If it will not stay up with everything unplugged, stop here, that points to a wiring or board fault and is a job for an electrician.
- If it does reset and hold, plug things back in one at a time, waiting a moment after each. When it trips again, the last thing you plugged in is very likely the culprit. Leave that appliance unplugged and get it checked or replaced.
- Note the timing. Does it trip when the shower runs, when it rains, when the dryer is on, or completely at random? That pattern is genuinely useful information for whoever fixes it.
Never open the consumer unit, poke inside it, or remove socket and switch fronts to investigate. Live parts behind those covers can kill, and there is no safe DIY check in there.
When should I just call an electrician?
Call someone in if the switch will not reset at all, if it trips again the moment you reset it with nothing plugged in, if there is any burning smell, scorching, buzzing or warmth at the board, or if you simply cannot pin it to a single appliance. Repeated tripping you cannot explain is your installation telling you something, and chasing an intermittent earth fault is exactly what a proper fault-finding visit is for. With the right test kit, Snelling Electrical isolates which circuit and which fault is causing it rather than guessing.
Could the fuse board itself be the problem?
Sometimes, yes. If you have an old board where one RCD covers everything, a single minor fault takes out half the house, which is both annoying and a sign the board is dated. Repeated nuisance tripping on an ageing board can mean the protective devices are simply worn out. In that case the proper fix is a modern board with individual RCBO protection per circuit, so a fault on one circuit only ever trips that one circuit. There are more clues in signs your fuse board needs replacing. Snelling Electrical looks at the cause first though, so you are never sold a new board when the real fault is a £30 kettle.