An RCD keeps tripping because it is detecting electricity leaking to earth somewhere on the circuits it protects — most often a single faulty appliance, sometimes damp or damaged wiring, and sometimes the small background leakage of several appliances adding up past the point the device will tolerate. It is a safety device doing what it was fitted to do, and the one response to avoid is resetting it over and over without finding out why. It is one of the most common calls we take from Nottingham homes. Here is what you can safely narrow down yourself, and where it stops being a job for the household. What is an RCD, and why does it trip? An RCD — a residual current device — is the switch in your consumer unit, or fuse board, that compares the electricity flowing out on the live conductor with the amount returning on the neutral. If some is going elsewhere, to earth through damp masonry or through a person, the two no longer match and the supply disconnects in a fraction of a second. That is what makes it the device most likely to prevent a fatal shock. Domestic RCDs are usually rated at 30 milliamps — thousandths of an amp. That sensitivity sits below the level at which a shock is likely to be fatal, which is also why an RCD is more easily upset than the fuses it replaced. Is an RCD tripping dangerous, or just annoying? Get someone out now if there is a burning smell, scorching or discolouration around a socket, switch or the board, buzzing or crackling, anything warm that should not be, or if the trips began after water got in. It can wait for a booked appointment if the power returns cleanly, the trips are occasional, nothing is hot or smells wrong, and you can link them to an appliance or an activity. Worth fixing properly, but not a fire risk overnight. Either way, if the RCD will not stay in, do not leave it off and carry on — the circuits beneath it are unprotected while it is out. What can I safely check before calling an electrician? Everything here is done from the front of a closed consumer unit and at the plug. None of it involves opening, testing or working on anything — that is for a registered electrician, and parts inside the unit stay live even with every switch off. • Look at what has gone off. Which lights and sockets are dead? In many Nottingham homes only half the house goes down, and which half is the most useful thing you can tell an electrician. • Read the labels on the board and note which circuits sit under the RCD that tripped. Do not remove the cover; if the labelling is unreadable, say so when you call. • Unplug everything on those circuits — appliances, chargers, extension leads, garden and garage items — and switch off anything on its own spur. • Reset the RCD once. If it holds, the fault is very likely in something you unplugged rather than in the fixed wiring. • Reintroduce appliances one at a time , several minutes apart, and actually use them. A washing machine often only trips twenty minutes in, when the heater comes on. • Stop if it will not hold with everything unplugged , or if it trips the instant you reset it. That points at the fixed wiring, and there is nothing more you can safely do. • Write down the pattern — time, weather, what was running. Do not use repeated resetting as a way of living with the problem: each one re-energises a circuit already known to be leaking. What does the pattern of tripping tell you? The circumstances narrow the field before anyone arrives. What you notice What it commonly points to Trips overnight or when the house is empty Something that cycles on its own — fridge, freezer, heating controls, timed outdoor lighting Trips part-way through an appliance cycle A heating element failing under load: washing machine, dishwasher, tumble dryer, oven Trips after heavy rain, or only in winter Moisture in an outdoor socket, garden supply, garage or exposed cable run Trips only when one item is used That appliance, or the socket and wiring serving it Trips at random, then holds fine Often accumulated background leakage across many appliances rather than one fault Will not reset even with everything unplugged A fault in the fixed wiring, or a failed RCD. Stop here The accumulated-leakage case is the one people find hardest to believe. Almost every modern appliance leaks a tiny current to earth by design, from the filters inside it. Individually that is nothing; a kitchen full of them can sit close enough to the threshold that anything else tips it over. BS 7671, the national wiring standard, recommends keeping standing leakage to no more than 30 per cent of the device rating — 9 milliamps on a 30 milliamp RCD. Where there is no single culprit, the answer is a design change rather than a repair. Why does half the house go off when one appliance faults? Because of how the board is arranged. A split-load consumer unit, the standard domestic pattern for years, puts one RCD over roughly half the circuits and a second over the rest, so a failing freezer in the kitchen can put your upstairs lights out. Newer boards use an RCBO per circuit instead, so only the faulty circuit disconnects. If your board trips regularly and takes half the property with it, that arrangement is often part of the answer. Replacing a consumer unit is notifiable work under Part P of the Building Regulations in England and Wales and must be certified by a registered electrician. Our guide to consumer unit replacement costs covers the job; Somo's range is £600 to £1,000 depending on the property and the number of circuits. What will an electrician actually do about a tripping RCD? Fault finding is measurement, not guesswork. Circuits are isolated one at a time and insulation resistance and earth leakage measured on each, which separates a genuine wiring fault from accumulated leakage and identifies the circuit rather than half the house. The fault is then traced to the accessory, cable or appliance responsible. Sometimes it is a five-minute answer — a failed extractor fan, water in an outside socket, a damaged flex. Sometimes it is cable nicked by a picture hook. Ask what the visit is charged at when you book: we do not publish a fault-finding price, because it is not one number. Frequently asked questions Can I just leave the RCD switched off if it keeps tripping? No. Everything on those circuits then runs without the protection that would disconnect the supply if someone got a shock, and the fault is still there. If you cannot restore power safely, isolate the affected appliances instead and get it looked at. Leaving an RCD off is not a temporary measure; it is removing the safety device. Why does my RCD trip at night when nothing is switched on? Because plenty is switched on. Fridges and freezers cycle their compressors automatically, heating and hot water run on timers, and outdoor lighting comes on by sensor. An appliance with a marginal fault often only trips the RCD as it starts up, and overnight is when that happens without anyone watching. Is a tripping RCD the same as a blown fuse? No, and the difference tells you what to look for. A fuse or an MCB responds to too much current on a circuit — an overload or a short. An RCD responds to current going missing to earth, a different fault with different causes. If the RCD operated, you are looking for a leak, not for too many things plugged in. Does an EICR find the cause of nuisance tripping? Usually, yes. An Electrical Installation Condition Report tests every circuit and measures insulation resistance and earth leakage — the same measurements used in fault finding. It is a sensible option if the tripping is intermittent and you also want the general condition of the wiring assessed, and landlords need one every five years anyway. Does the 2026 change to the wiring regulations affect my RCD? Not retrospectively. Amendment 4 to BS 7671 was published on 15 April 2026 and becomes the standard for new work when the previous version is withdrawn on 15 October 2026. It does not make an existing compliant installation unlawful, but it does affect how new and altered circuits are designed — so ask which version remedial work will be carried out to. Fault finding with Somo Electrical Somo Electrical is a NAPIT-registered electrical contractor working across Nottingham. We trace tripping faults by measurement rather than by replacing parts until it stops, and say plainly whether it is a failing appliance, a wiring fault or a board no longer suited to the house. Around Wollaton , much of the housing stock still has split-load boards fitted when a kitchen held a fraction of the appliances it does now. If the power keeps going off and you have worked through the checks above, call 07733 666004 or use our online quote form . For a burning smell or anything hot, treat it as urgent — see emergency electrical repairs . Where the board is the answer, our consumer unit upgrades page sets out that work. All inspection, testing and repairs are by qualified, registered electricians. Sources checked 21 August 2026: BS 7671:2018 and Amendment 4 (published 15 April 2026, previous version withdrawn 15 October 2026); regulation 531.3.2 on standing protective conductor current; Part P of the Building Regulations (England and Wales). RCD safety guidance is published by Electrical Safety First and the IET. Prices are Somo Electrical's own ranges and are not a quote.