If your RCD won’t reset, it’s almost always because a genuine earth-leakage fault is still present — the device is refusing to re-energise a circuit it considers unsafe. First push the switch fully down to the off position, then firmly up: RCDs won’t reset from the halfway “tripped” position. If it still won’t hold, unplug every appliance on the protected circuits and try again; if it holds, one of your appliances is faulty, and if it still won’t hold, you have a wiring fault and need an electrician.
Safe checks to try first (switches and plugs only)
Everything here is done from the front of the consumer unit and at your sockets. Do not remove the consumer unit cover, and don’t touch any wiring — if a step needs a screwdriver, it’s not a DIY step.
- The off-then-on reset trick. A tripped RCD often sits in a middle position and won’t respond to being pushed up. Push it firmly all the way down to OFF first, pause, then push it up to ON in one firm movement. A surprising number of “broken” RCDs reset perfectly once they’ve been fully reset from off.
- Switch off the MCBs, then reset. If your board layout allows, switch off the individual circuit switches (MCBs) covered by that RCD, reset the RCD, then switch the MCBs back on one at a time. The one that knocks the RCD back off tells you which circuit carries the fault.
- Unplug absolutely everything on the affected circuits. Every plug, every room — including the forgotten ones: fridge-freezer, washing machine, dishwasher, boiler plug, garage freezer, garden sockets, TV standby, chargers. Then try the reset again.
- If it now holds, reconnect one appliance at a time. Wait a minute or two between each. The appliance that trips it is your fault — leave it unplugged and have it repaired or replaced.
- Think about damp and recent changes. Heavy rain, a leak, a newly cleaned oven (moisture in the element), drilling into a wall, or building work are all classic triggers for an RCD that suddenly won’t reset.
Stop and call a professional if: the RCD won’t hold with every appliance unplugged and all MCBs off, it resets but trips again within seconds or minutes for no reason, you smell burning or see scorching anywhere, or the RCD feels loose, buzzes or arcs when you operate it. At that point the fault is in the fixed wiring, the board or the device itself — none of which you can reach safely.
Why forcing it makes things worse
Holding the RCD switch up, taping it, or repeatedly slamming it back on doesn’t bypass the fault — the device will keep tripping, and each re-energisation pushes fault current through whatever is damaged. If the fault is a cable with compromised insulation or a damp junction, repeated forcing turns a trip into heat, and heat into fire risk. It can also wear out the RCD’s mechanism, adding a broken protective device to your original fault. Two or three reset attempts during troubleshooting is fine; beyond that, stop.
What’s actually causing it — faults ranked by how often we find them
- A faulty appliance. The cause in the majority of call-outs. Heating elements are the usual suspects — washing machines, dishwashers, immersion heaters, ovens and kettles — because elements leak current to earth as they age.
- Moisture and damp. Water in outdoor sockets, garden lighting, a shed supply, a bathroom fan or a leak dripping onto a junction box. If the problem started during or after rain, this is where we look first.
- Damaged cables. A screw or nail through a cable from shelving, flooring or picture-hanging work — sometimes tripping instantly, sometimes weeks later as the insulation breaks down.
- Accumulated earth leakage. Modern homes carry constant small leakage from LED drivers, computers, EV chargers and induction hobs. Individually fine; together they can sit just under the RCD’s threshold so that one more small fault tips it over. The fix is often splitting circuits or upgrading to RCBOs.
- Deteriorated fixed wiring. Ageing rubber- or early-PVC-insulated cable, common in older London housing stock, leaks to earth as the insulation degrades.
- A faulty RCD. Genuinely the least common cause, despite being everyone’s first guess. RCDs do wear out, but we always prove the installation healthy before condemning the device.
When it’s an emergency
Call an emergency electrician rather than booking a routine visit if the RCD that won’t reset controls your whole supply (no lights, heating, hot water or fridge), if there’s any burning smell or scorching, if someone has felt a shock, or if a vulnerable person or medical equipment depends on the power. Our 24-hour emergency electrician service in London handles exactly this — an RCD that won’t reset at 11pm with a fridge full of food is one of our most common night calls. If only one non-essential circuit is affected and the house is otherwise fine, leaving that circuit off until a daytime visit is a sensible, cheaper option.
What our electrician will do
- Test the RCD itself — trip current and trip time — to establish whether the device or the installation is at fault
- Isolate and reconnect circuits systematically to pinpoint the faulty circuit
- Run insulation-resistance tests on that circuit to find earth leakage, and trace it to a point: an accessory, a junction, a damp section or a damaged cable
- Check for DIY damage, moisture ingress and deteriorated terminations along the way
- Repair the fault, or where the cause is cumulative leakage, recommend splitting the load across RCBOs so one fault can never black out half your home again
Everything is tested before we re-energise, and you get a plain-English explanation of what we found. As a NICEIC Approved Contractor, our fault repairs are carried out and certified to BS 7671.
What it costs
Our minimum charge for any visit is £108 including VAT (£90 + VAT), covering the call-out and fault-finding. Prices are labour-only, and most RCD faults are traced and fixed in a single visit. If further work is needed — a repaired cable, a replacement RCD, a board upgrade — we quote a fixed price before the work starts. If the underlying issue is an old split-load board that keeps nuisance-tripping, see our guide to fuse board replacement costs in London for what an RCBO upgrade involves.
Frequently asked questions
What’s the difference between an RCD and an MCB?
An MCB protects one circuit against overload and short circuits. An RCD protects people, tripping in milliseconds when current leaks to earth — through damaged insulation, water or a human body. On many boards one RCD covers several MCBs, which is why one fault can take out half the house.
My RCD resets but trips again after a few minutes. Same problem?
Usually yes — an intermittent version of it. Heat-dependent appliance faults and damp are the classic causes of delayed re-trips. Follow the same unplug-and-isolate steps; if it persists with everything unplugged, it needs professional fault-finding.
Should I press the test button?
The T or Test button is for routine checks (recommended quarterly) when the RCD is holding normally. It won’t help diagnose an RCD that’s already refusing to reset — and if the RCD holds but the test button doesn’t trip it, the device itself is faulty and needs replacing.
How fast can you get here?
Same-day across most of north and east London, often within the hour for full-power-loss emergencies. See our London service areas for coverage.
RCD still won’t reset? Call F & A Electrical
Rated 9.69/10 from 237 Checkatrade reviews, we trace and fix RCD faults across London every week. Call 07407 627542 or 07500 721453 — tell us what you’ve already tried and we’ll tell you honestly whether it needs someone tonight or can wait until morning.
Common electrical faults — more guides
Fuse box keeps tripping · Burning smell from a socket · No power in half the house · Lights flickering