On this page
- The switch that dropped tells you where to look
- How to find out what is tripping your electric
- When the trip switch on your fuse box won't stay up
- Why your electric keeps tripping when everything is off
- Why your electric keeps tripping when it rains
- A fuse blown in an old fuse box
- When a circuit breaker that keeps tripping is dangerous
- Landlords: a tenant reports tripping
- What finding the fault costs
The short version
- The switch that dropped shows where to look: one breaker means that circuit, an RCD means leakage across several.
- Unplug everything, reset once, then reconnect appliances one at a time to find a faulty one.
- A trip switch that won't stay up with everything unplugged points to a wiring fault: leave it off and call.
- Never hold a switch up or bypass it, and stop resetting if you smell burning.
- Diagnosing a tripping fuse box in London costs from £90, including VAT.
A fuse box that keeps tripping is protecting you from a fault: a circuit drawing too much current, a short circuit, or current leaking to earth. Which switch dropped tells you where to look. One circuit breaker usually means an overloaded circuit or a faulty appliance on it. An RCD taking several circuits off at once points to leakage from an appliance, damp or the wiring.
Most trips have an ordinary cause you can find in a few minutes. Some are a fault that needs an electrician, and the checks below show you which.
The switch that dropped tells you where to look
A modern consumer unit, the current name for a fuse box, has up to three kinds of switch. Open the clear flap, without undoing any screws, and find the one that is down.
| Switch that dropped | What it protects | What it usually means |
|---|---|---|
| One circuit breaker (MCB) | A single circuit, such as the upstairs sockets or the kitchen | Too much load on that circuit, a faulty appliance on it, or a short circuit |
| An RCD, with several circuits off | A group of circuits, against current leaking to earth | An appliance leaking current, damp in a fitting, or a wiring fault somewhere in that group |
| One RCBO | A single circuit, against both overload and leakage | Either of the above, confined to that one circuit |
| The main switch | The whole installation | Usually an on/off switch only. On some boards it is an RCD covering every circuit, so treat it as an RCD trip |
Fuse box switches: up is on, down is off
On almost every modern consumer unit, up is on. A switch that is down, or sitting partway down, has tripped or been switched off. RCDs and RCBOs carry a small test button, usually marked T. A plain circuit breaker has none, which is the quickest way to tell them apart.
How to find out what is tripping your electric
These five checks are the only ones a homeowner should make. None of them means removing the consumer unit cover or touching any wiring.
- Note which switch is down before touching anything, whether it is an MCB, an RCD or an RCBO, and which rooms have lost power.
- Unplug everything on the affected circuits, and switch off fixed appliances such as the cooker, electric shower and outdoor lights at their own switches.
- Reset the switch once. Push it firmly back up. If it will not stay up with everything unplugged, stop here.
- Plug appliances back in one at a time, switching each on for a minute. If the switch drops when one goes on, that appliance is the likely cause.
- Leave the suspect appliance unplugged and have it repaired or replaced. Kettles, washing machines, dishwashers and old extension leads are common culprits.
When the trip switch on your fuse box won't stay up
A switch that drops again the instant you push it up, with everything on those circuits unplugged, means the fault it detected is still there: a short circuit, current leaking to earth or a problem in the wiring.
Leave it off rather than trying again and again. An electrician will find the fault faster if you can say:
- which switch it is, and whether it drops instantly or after a while
- whether it started after rain, or after someone drilled a wall or put up a picture
Sometimes the fault is inside the board itself, such as a loose connection at the main switch or behind the breakers. That is never one to investigate yourself.
Why your electric keeps tripping when everything is off
If the RCD still drops with every appliance unplugged and switched off, the fault is almost certainly in the fixed wiring or a fitting. An RCD tripping with nothing plugged in is the point to book electrical fault finding rather than keep resetting.
Unplugging also leaves wired-in items connected: extractor fans, smoke alarms, an immersion heater and outdoor lights. Any of them can carry the fault.
How an RCD decides to trip
An RCD compares the current flowing out along the live conductor with the current coming back along the neutral. If some goes missing, it is leaking to earth, possibly through a person, and the RCD cuts the supply.
Homes use 30 mA RCDs. In practice one often trips at around 22 mA, well below its rating.
Small leaks that add up
Computers, TVs, chargers and many appliances leak a little current to earth by design. Around 10 mA of that spread across one RCD's circuits leaves only about 12 mA before it trips, so one appliance with a slight fault can tip it over.
Faults in the fixed wiring
- A nail, screw or picture hook driven through a cable under a floorboard or inside a wall
- A neutral touching earth somewhere on a circuit. A breaker normally switches the live but not the neutral, so this can trip the RCD even with that circuit's breaker off
- Damaged cable in a loft, garage or garden supply
Why your electric keeps tripping when it rains
Water lowers the insulation around live parts, and a small path to earth is exactly what an RCD detects. Tripping in wet weather usually traces back to one of these:
- an outdoor socket or garden light with water inside it
- a shed or garage supply whose cable or fittings have let water in
- damp plaster or condensation around a socket, switch or light
A single trip in a thunderstorm can start outside your home, since lightning and switching on the supply network can both trip an RCD. Tripping every time it rains means water is getting in somewhere.
A cooker that trips it at first switch-on
The elements in some cookers absorb moisture while they sit cold, then leak enough current at first switch-on to trip an RCD. Once and it settles, that is the likely reason; if it keeps happening, have the cooker checked.
A fuse blown in an old fuse box
Older boards do not trip. Each circuit has a fuse, and a fault or overload heats the fuse wire until it melts, which cuts the circuit off. A blown fuse means the same as a tripped breaker, so start with the same checks and unplug everything on that circuit.
Do not rewire the fuse yourself. Fuse wire thicker than the circuit's rating takes away its protection, and some older boards contain asbestos parts or are mounted on asbestos board.
A board with rewireable fuses also has no RCD, so nothing in it protects against electric shock. Our guide to old fuse boxes explains whether yours needs replacing.
When a circuit breaker that keeps tripping is dangerous
The trip is the protection working. Repeated tripping means a fault in an appliance or the wiring, so stop resetting and call an electrician if:
- You smell burning, or see scorch marks on a socket, switch or the consumer unit
- You hear buzzing or crackling from a fitting or the board
- The switch trips again the moment you push it up
- It trips with every appliance unplugged and switched off
Our electricians in London trace the circuit, test the wiring and put the cause right, whether that is one damaged cable or an ageing board. Call 07727 619854.
Landlords: a tenant reports tripping
Treat a tripping report as a repair to arrange, not something for the tenant to keep resetting. Tripping with nothing plugged in is a wiring fault in a property you are responsible for.
Private landlords in England must have the installation inspected at least every five years and complete any work the report calls for within 28 days, or sooner if it says so. Our landlord EICR service in East London covers the inspection and the remedial work.
What finding the fault costs
Our guide price for diagnosing a tripping fuse box starts from £90, typically £90–£150, including VAT. The repair is quoted once the cause is found, and you decide before any work starts.
| Job | Guide price (VAT included) |
|---|---|
| Diagnosing a tripping fuse box | from £90 |
| Fault finding (minor) | from £100 |
| Replacing a damaged socket or switch | from £80 |
| Replacing the consumer unit | from £400 |
For a price on your own fault, call 07727 619854 or request a quote online.
Frequently asked questions
Up is on. A switch that is down when nobody turned it off has tripped: unplug everything on that circuit and push it back up once. If it will not stay up, leave it off and call an electrician.
They detect different faults. A circuit breaker trips on overload or a short circuit, while an RCD trips when current leaks to earth from a faulty appliance, damp or damaged wiring. An RCD trip with every breaker still up points to leakage, not too much load.
The trip is the breaker doing its job, but repeated tripping means a fault in an appliance or the wiring, and it will not clear itself. A burning smell, scorch marks or a switch that drops the moment you reset it mean you should stop using that circuit and have it checked.
Either that appliance has a fault, or it pushes an already busy circuit past its limit. If it trips an RCD, or trips a breaker even with nothing else on that circuit, the appliance is the likely fault and needs repairing or replacing.