If your RCD keeps tripping, the most likely cause is a faulty appliance leaking current to earth — usually something with a heating element, like a kettle, toaster, washing machine or oven. The fix is a process of elimination: unplug everything, reset the RCD, then plug things back in one at a time until you find the culprit.

It is one of the most common fault-finding calls we get across Bristol, and you can usually trace the cause safely yourself, without taking the cover off the fuse board (consumer unit).

Tripping you can’t trace? Call Mark on 07973 782 821 — 24/7 emergency call-out across Bristol and surrounding areas — or request a free quote. Based in Downend. No call-out charge for quotes, and no obligation.

RCD or circuit breaker: which one has actually tripped?

Open the flap on your fuse board and you’ll see a main switch, one or two larger switches (the RCDs), and a row of smaller ones (MCBs — the “circuit breakers”). Knowing which one has flipped down tells you a lot.

An RCD (residual current device) watches for current leaking out of a circuit — through damaged insulation, water, or a person. It trips in a fraction of a second at a leak of around 30 milliamps, small enough to save your life; Electrical Safety First has a good plain-English explainer. An MCB trips on too much current: an overload or a dead short.

If a single circuit breaker keeps tripping rather than the RCD, you have an overload or a short on that one circuit — work through that circuit’s sockets and fittings the same way. If half your house has gone dead at once, that is normally one RCD covering its side of a split-load board — see our guide to half the house losing power.

What to do when your RCD keeps tripping: the safe reset routine

Everything below happens at the sockets and on the front of the fuse board — never remove the board’s cover. If anything smells hot or looks scorched, switch off at the main switch and call an electrician instead.

1. Unplug everything you can — fridge, freezer, washing machine, dishwasher, TV, chargers. Switch off anything you can’t unplug at its wall switch: cooker, immersion heater, electric shower.
2. Reset the RCD. Push it firmly to on; on many models the switch must travel fully down before it will latch back up.
3. If it holds, reconnect one thing at a time, waiting a minute between each. When it trips again, the last thing you plugged in is your culprit. Switch heating appliances on and let them warm up — plenty of faults only show once the element is hot.
4. If it won’t hold with everything unplugged, switch off all the MCBs under that RCD, reset the RCD, then switch the MCBs back on one at a time. The one that trips it identifies the faulty circuit.
5. If it trips instantly with every MCB off, the fault is in the board itself or something wired directly into it. Stop there and call a qualified electrician.

Found it? Leave the culprit unplugged — or that circuit’s MCB off — and get it repaired or replaced.

Common causes of RCD tripping, ranked

In rough order of how often we find them on fault-finding jobs:

1. A faulty appliance. Far and away the most common cause. Anything with a heating element or a motor: kettles, toasters, washing machines, dishwashers, tumble dryers, ovens and immersion heaters.
2. Water where it shouldn’t be. Outdoor sockets, garden lighting, pond pumps, shed supplies and security lights all live hard lives. If the trips line up with wet weather, read our guide to electrics tripping when it rains.
3. A damaged cable. A nail or screw through a cable during DIY, rodents chewing insulation in the loft, or a cable crushed under a floorboard. These usually show as a whole circuit that won’t hold rather than one appliance.
4. Nuisance tripping. Every modern gadget leaks a tiny, harmless current to earth. Enough computers, chargers and LED drivers on one RCD and the total sits just under the trip threshold — one small extra load tips it over.
5. A fault at the board. RCDs are mechanical devices and wear out, especially ones that have tripped hundreds of times. A loose connection inside the board can do the same.

Why the kettle and toaster are the usual suspects

Heating elements fail in a particular way. The element wire is packed in mineral insulation inside a metal sheath, and that insulation slowly absorbs moisture through hairline cracks as the appliance ages. Heat the element and current leaks through the damp insulation to the earthed sheath — the RCD trips.

The classic pattern is a kettle that trips the RCD the moment it is switched on, or partway through boiling. Toasters do the same, helped along by years of crumbs. A faulty element can also dry out and behave for days before tripping again — it has not fixed itself, it is on the way out. Replace small appliances; on an oven or immersion heater, a new element is often the economical fix.

RCD tripping randomly with no obvious cause

Intermittent trips are the ones that drive people mad. The pattern is usually the clue:

• Trips at night or while you’re out — almost always an appliance that switches itself on: a fridge or freezer defrost cycle, or an immersion heater on a timer.
• Trips in wet or windy weather — water getting into outdoor fittings or an external junction box.
• No pattern at all — cumulative leakage sitting close to the threshold, a rodent-damaged cable, or a worn-out RCD.

Before you call anyone, note the date, time, weather and what was running each time it trips. A week of notes can cut fault finding from hours to minutes.

When it means a real fault, and what fixing it costs

An RCD that trips once in a blue moon is doing its job. Call a qualified electrician when:

• It will not reset at all, even with everything unplugged and the MCBs off.
• One circuit trips it with everything on that circuit unplugged — that points to a wiring fault, not an appliance.
• The trips are getting steadily more frequent.
• There is any burning smell, buzzing or scorching at the board or a socket. Switch off at the main switch and treat it as urgent — see our guide to burning smells from sockets and fuse boards.

Typical costs, as a guide:

These are typical ranges, not quotes — our guides to emergency electrician call-out costs and fuse board replacement costs in Bristol have the detail.

One honest recommendation: if your board suffers chronic nuisance tripping, or one RCD covers half the house, the best long-term fix is usually a new board with RCBOs — a combined RCD and MCB for each circuit — plus surge protection. A faulty kettle then takes out the kitchen sockets and nothing else.

Frequently asked questions

Is it safe to keep resetting my RCD?

Resetting once or twice while you hunt for the cause is fine — that is what the switch is for. Repeatedly resetting without finding the cause is not: the device is telling you current is leaking somewhere. Never wedge or tape an RCD on. If it won’t hold with everything unplugged, get it looked at.

How much does it cost to fix an RCD that keeps tripping?

Often nothing beyond a new kettle or toaster, if elimination finds a faulty appliance. If the fault is in the wiring, expect fault finding at a typical £40–£60 per hour plus the repair; a worn-out board is typically £450–£700 to replace. We give a clear price before any work starts.

Can my fridge or freezer trip the RCD?

Yes, and they are easy to miss because they switch themselves on and off. Compressors draw a brief surge on starting, and defrost elements suffer the same moisture problem as kettle elements. If trips seem random, try running the fridge or freezer from a socket on a different RCD for a few days.

RCD still tripping? Call Mark on 07973 782 821 — 24/7 emergency call-out across Bristol and surrounding areas — or get a free fixed-price quote. Fault finding with a clear price up front, no call-out charge for quotes, and no obligation.