If your fuse box keeps tripping, the most likely cause is a faulty appliance, an overloaded circuit or a wiring fault — and the switch is doing its job by cutting the power. Unplug everything on the affected circuit, reset the switch, then plug items back in one at a time to find the culprit. If it trips again with everything unplugged, stop: that points to a wiring fault, and you need an electrician rather than another reset.
Safe checks you can do yourself (without opening anything)
Everything below can be done from the front of your consumer unit — the row of switches, usually in the hallway, under the stairs or by the front door. You should never remove the cover, poke inside the unit or touch any wiring. If a check involves more than flicking a switch or unplugging a plug, it’s not a DIY check.
- Look at which switch has dropped. A small switch down usually means one circuit (an MCB) — lights, sockets, cooker or shower. A larger switch controlling several circuits is an RCD, which trips on earth-leakage faults and often means a faulty appliance or damp.
- Unplug everything on the affected circuit. Kettles, washing machines, tumble dryers, heaters, phone chargers, extension leads — the lot. Don’t forget hidden items like fridge-freezers and boiler plugs.
- Reset the switch firmly. Push it fully down to off first, then up to on. Some switches won’t reset unless they’re moved fully to the off position first.
- Plug appliances back in one at a time. Wait a minute or two between each. When the trip happens again, the last thing you plugged in is your prime suspect. Leave it unplugged and get it repaired or replaced.
- Think about what changed. New appliance? Heavy rain? DIY drilling or picture-hanging? Building work next door? Trips often start right after something in the house changed.
Stop and call a professional if: the switch trips instantly with everything unplugged, it won’t stay on at all, you see scorching or smell burning at the fuse box or any socket, the trips are getting more frequent for no obvious reason, or your board still has old rewirable fuses rather than switches. None of those situations is fixable from the outside of the unit.
Why your fuse box keeps tripping — 7 common causes, ranked
- A faulty appliance. By far the most common cause we find on call-outs across London. Kettles, washing machines, dishwashers, immersion heaters and cheap phone chargers top the list. Heating elements in particular break down gradually, which is why trips often start intermittently.
- An overloaded circuit. Too many high-demand appliances on one circuit — classic in older London terraces where a single ring serves the whole kitchen. The fix might be as simple as spreading the load, or the circuit may need upgrading.
- Moisture and damp. Outdoor sockets, garden lighting, leaking bathrooms and condensation in kitchen extractor fans all cause earth leakage that trips the RCD — often only when it rains.
- Damaged cables. A nail or screw through a cable during shelving or flooring work can cause trips that start the same day, or weeks later once the insulation finally breaks down.
- A worn or nuisance-tripping device. MCBs and RCDs wear out. An ageing RCD can become oversensitive; conversely, accumulated leakage from modern electronics (LED drivers, EV chargers, induction hobs) can push a healthy RCD past its threshold.
- Loose connections. Connections work loose over years of heating and cooling. Loose terminals cause arcing, which trips circuits and — left alone — starts fires.
- Deteriorated wiring. Rubber- or fabric-insulated cable from the 1950s–60s, still common in unrenovated London properties, crumbles with age and leaks current to earth.
Five more causes we see less often (but do see)
The seven above account for most call-outs. If none of them fit, these are the next most likely — and all five need testing rather than guesswork.
8. A failing electric shower
Shower elements degrade and start leaking current to earth, usually tripping the RCD a few seconds after the shower is switched on. If the board only trips when someone showers, that is the fault. A shower on its own dedicated circuit and RCBO is the correct fix.
9. A loose connection inside the consumer unit
Terminals work loose over years of thermal cycling. Loose connections arc, heat up and trip the breaker under load. This is one of the more serious findings because it is a genuine fire risk — it is also invisible without removing the cover, which is why we torque-check every terminal on an EICR.
10. Accumulated earth leakage (nuisance tripping)
Every appliance leaks a tiny amount of current to earth. Nothing is faulty, but once enough appliances are running the total creeps past the RCD’s 30mA threshold and the whole board goes. Typical on older boards where one RCD covers half the house. Splitting the circuits across RCBOs so each circuit is protected individually solves it permanently.
11. Surge or lightning damage
A nearby strike or a supply surge can damage breakers and appliance electronics at the same time, so the tripping starts abruptly with no change in how you use the property. Since Amendment 2 of BS 7671, surge protection (SPD) is expected on most new consumer units.
12. An EV charger the supply cannot support
A 7kW charger on an already-loaded 60A or 80A supply will trip the main switch when the shower, oven and charger coincide. The fix is load curtailment on the charger or a supply upgrade through your DNO — not a bigger breaker.
When tripping is an emergency
Treat it as urgent — and call an emergency electrician rather than waiting for a routine appointment — if any of these apply:
- You can smell burning or see scorch marks at the fuse box, a socket or a switch
- The main switch or RCD won’t stay on, leaving you without power, heating or hot water
- Trips are accompanied by buzzing, crackling or flickering lights
- Someone has felt a tingle or shock from an appliance, tap or switch
- You have a vulnerable person, young children or medical equipment relying on the supply
We run a genuine 24-hour emergency electrician service across London, with fast response across north and east London postcodes. If it’s after midnight and the house is safe with the circuit simply left off, leaving it off until morning is a perfectly sensible option — we’ll tell you honestly on the phone which situation you’re in.
What our electrician will actually do
Fault-finding is methodical, not guesswork. On a typical tripping call-out we will:
- Test the RCD and MCBs to confirm they’re operating correctly and not nuisance-tripping
- Isolate circuits one by one to identify exactly which circuit carries the fault
- Carry out insulation-resistance and earth-leakage tests to distinguish an appliance fault from a wiring fault
- Inspect accessible connections at sockets, switches and junctions for looseness, damage or overheating
- Repair the fault where possible on the spot, or make the installation safe and give you a fixed price for the remedial work before anything further starts
You get a clear explanation of what was wrong and written confirmation of any work done. As a NICEIC Approved Contractor, all our work is carried out and certified to BS 7671 (18th Edition) standards.
What a tripping fault call-out costs
Our minimum charge for any visit is £108 including VAT (£90 + VAT), which covers the call-out and initial fault-finding. Prices are labour-only, and most tripping faults are diagnosed within the first visit. If the fix needs parts or further work — a replacement MCB, a repaired circuit, a new socket — we quote you a fixed price before any work starts, so there are no surprises on the invoice. No hidden hourly meters, no “while we’re here” extras.
Old fuse box? When replacement beats repair
If your board still has rewirable fuses, no RCD protection, or it’s a pre-2008 Wylex, MEM or MK unit, repeated tripping is often the installation telling you it’s overdue an upgrade. A modern consumer unit with RCBOs protects each circuit individually — so a faulty kettle trips one circuit instead of blacking out half the house. See our guide to fuse board replacement costs in London for what’s involved and what to budget.
Frequently asked questions
Is it dangerous if my fuse box keeps tripping?
The tripping itself is the safety system working. The danger is the underlying fault it’s reacting to — and repeatedly resetting without finding that fault means repeatedly re-energising a potentially damaged circuit. Find the cause or call us.
Why does my fuse box trip when it rains?
Water is getting into something on an outdoor or exposed circuit — garden sockets, outside lights, a shed supply or a damaged cable. It needs tracing and sealing or repairing; it will not fix itself.
Can I just keep resetting the switch?
Once or twice while you troubleshoot, yes. Repeatedly forcing a tripping circuit back on is how minor faults become burnt-out cables. If it won’t hold after your appliance checks, stop resetting and call an electrician.
How quickly can you get to me?
Same-day for most of north and east London, and often within the hour for genuine emergencies. Check our London service areas — and if you’re local to us in N15, see our Tottenham electrician page.
Fuse box tripping? Call F & A Electrical
We’re rated 9.69/10 from 237 Checkatrade reviews, and tripping faults are our bread and butter. Call 07407 627542 or 07500 721453 now — describe what’s happening and we’ll tell you straight away whether it can wait until morning or needs someone tonight.
Common electrical faults — more guides
Burning smell from a socket · RCD won’t reset · No power in half the house · Lights flickering