Why Does My RCD Keep Tripping?

Written and technically reviewed by Steven Watt, NICEIC Approved Contractor enrolment 620239. Last reviewed 13 September 2026.

If your RCD keeps tripping, it is usually reacting to current leaking from the normal electrical path. The cause may be a faulty appliance, water in an outdoor fitting, damaged wiring, a neutral to earth fault, or the combined leakage from several items. Less commonly, the RCD itself may be defective.

Do not keep forcing the switch back on. Unplug portable appliances, switch off the affected circuits if you can identify them, and try one careful reset. If it trips again, will not stay on, or there is a burning smell, heat, buzzing, smoke, visible damage or signs of water near electrical equipment, leave the affected supply off and contact a qualified electrician.

This guide explains what an RCD does, how to narrow down the likely cause without opening electrical equipment, and what an electrician tests when the fault is hidden. It is written by Faithful Spark Electricians, a NICEIC Approved Contractor based in Peterhead and working across Aberdeen and Aberdeenshire.

What to do first when an RCD trips

Stop before you do anything else.

Do not open the consumer unit cover, touch any wiring inside it, remove panels or use tools. If you can see exposed conductors, scorch marks or burning, or you can smell burning anywhere in the house, do not touch anything and call an electrician urgently.

What you find	What to do
Smoke, burning smell, crackling, scorching or heat	Do not reset the RCD. Switch off the supply only if it is safe to do so, keep people away and call an electrician urgently.
Water entering a socket, light, appliance or consumer unit	Do not touch wet electrical equipment. Keep the circuit off and arrange professional inspection.
The RCD trips once and resets normally	Note what was running. Watch for a pattern, but do not assume the fault has disappeared.
It trips whenever one appliance is used	Unplug that appliance and stop using it. Do not dismantle it. The appliance or its supply may need testing.
It trips with everything unplugged	Leave the affected circuits off and call an electrician. Fixed wiring, hardwired equipment or a neutral to earth fault may be involved.
It will not reset at all	Turn the protected circuit breakers off, then try one reset. If it still will not hold, stop and obtain professional help.

An RCD trip is a safety warning, not an inconvenience to defeat. The Health and Safety Executive advises that obviously defective electrical equipment should be taken out of use and that electrical installations should be inspected and tested by someone competent.

What an RCD actually does

RCD stands for residual current device. It compares the current flowing out through the live conductor with the current returning through the neutral. Under normal conditions those values are effectively balanced. If some current takes another path, perhaps through damaged insulation, damp material, protective conductors or a person, the RCD detects the imbalance and disconnects the supply.

Many domestic RCDs provide additional protection at a rated residual operating current of 30 milliamps. That protection can reduce the severity of certain electric shocks, but an RCD cannot prevent every type of shock and it does not make unsafe electrical work safe. The HSE states that circuits must still be securely isolated before work begins.

The RCD does not measure ordinary electricity use in the same way as a fuse or miniature circuit breaker. A high powered appliance can operate normally without tripping an RCD when the outgoing and returning currents remain balanced. Conversely, a tiny leakage current can trip it even when the appliance is using little power.

RCD, RCBO and circuit breaker differences

Device	What it monitors	What a trip usually indicates
RCD	Residual current across several circuits	Earth leakage somewhere on one of the circuits it protects, or a fault involving the RCD or associated conductors.
RCBO	Residual current plus overload and short circuit current on one circuit	A fault is already narrowed to one circuit, although testing is needed to determine whether the cause is leakage, overload or a short circuit.
MCB or circuit breaker	Overload and short circuit current	Excess current, a short circuit or a fault causing the breaker’s protective element to operate.
Main switch	Manual isolation only	It normally does not trip automatically. If it appears to have moved or feels abnormal, arrange inspection.

Older split load consumer units often place several circuits behind one RCD. A single damp outside light can therefore disconnect sockets, heating controls and other unrelated equipment. A modern full RCBO consumer unit protects circuits individually, which reduces disruption and makes the affected circuit easier to identify.

The most common reasons an RCD keeps tripping

A faulty appliance

Portable and fixed appliances are frequent causes of RCD operation. Heating elements, motors, filters, pumps and internal wiring can deteriorate with age. Washing machines, dishwashers, tumble dryers, kettles, ovens, immersion heaters, fridges and freezers are common suspects because they combine heat, moisture, vibration or long operating periods.

A fault may only appear at one stage of an appliance cycle. A washing machine might run normally until its heater energises. A fridge may trip the RCD only when the compressor starts. An oven element may leak to earth as it becomes hot, then appear normal again after cooling.

Water or condensation

Water ingress is especially common in outdoor sockets, security lights, garden lighting, sheds, garages and junction boxes. In coastal areas such as Peterhead and Fraserburgh, wind driven rain and corrosion can weaken seals and connections. The trip may follow heavy rain rather than occur while the equipment is being used.

Bathrooms, utility rooms and kitchens can also produce condensation. Never remove covers or touch wet accessories to investigate. Isolate the circuit if you can do so safely and let an electrician assess the equipment and wiring.

Damaged cables or accessories

A screw through a cable, a crushed flex, rodent damage, deteriorated insulation or a loose connection can create an earth fault. Damage can remain hidden until movement, moisture or heat changes the fault enough for the RCD to operate. This is why intermittent trips can take longer to diagnose than a permanent fault.

Think about recent work before the tripping began. Shelving, flooring, loft boarding, kitchen fitting, landscaping and outside lighting work may all disturb cables. Tell the electrician what changed, even if the work seems unrelated.

A neutral to earth fault

A neutral conductor touching earth can cause confusing symptoms. The RCD may trip only when another load is switched on, when circuits are combined, or after alterations at the consumer unit. Turning off a circuit breaker does not always separate its neutral conductor, so a neutral to earth fault can remain connected and continue to affect the RCD.

This is one reason the common advice to turn breakers on one at a time does not locate every fault. Proper isolation and electrical testing are required. A homeowner should not remove the consumer unit cover or disconnect neutral conductors.

Combined earth leakage from several devices

Electronic equipment often contains filters that allow a small designed leakage current to earth. One item may be well within its normal limits, but several computers, televisions, chargers, LED drivers, heating controls and appliances on the same RCD can add together. The total may approach the point where the RCD operates, particularly when one appliance adds a little more leakage during startup.

This is sometimes called cumulative or standing leakage. It does not prove that every connected item is faulty. An electrician can measure leakage current and decide whether there is a defective item, unsuitable circuit division or another fault.

An incorrect connection or recent electrical work

Borrowed neutrals, crossed neutrals, incorrect circuit separation and wiring errors can cause an RCD or RCBO to trip as soon as a load is used. These faults sometimes appear after a consumer unit change, a lighting alteration or work that combines supplies from different protective devices.

If the problem started immediately after electrical work, tell the contractor exactly when it began and which circuits are affected. Do not accept repeated resetting as a solution. The installation should be tested and the connection error corrected.

The RCD itself may be faulty

RCDs can fail, but replacement should not be the first guess. A new device may appear to solve an intermittent problem temporarily while the actual cable or appliance fault remains. An electrician can test the device’s operating current and time, inspect its connections, and test the protected circuits before deciding whether it needs replacement.

Why the timing of the trip matters

Pattern	Likely areas to investigate
Trips instantly when reset	A persistent earth fault, neutral to earth fault, connected faulty appliance, wiring error or defective RCD.
Trips when one appliance starts	The appliance, its flex, the socket, or leakage that increases when a heater, motor or compressor operates.
Trips after a few minutes	An element or connection changing as it heats, an appliance cycle, moisture, or accumulated leakage.
Trips overnight	Fridge or freezer cycles, immersion heating, storage heating, boiler controls, outside lighting, chargers or timed equipment.
Trips after rain	Outdoor lights, sockets, garden equipment, garage or shed supplies, damaged seals or underground connections.
Trips when several appliances run	Cumulative leakage, a marginal fault revealed by load, or a separate overcurrent issue if an MCB or RCBO rather than the RCD is operating.
Trips randomly every few days	Intermittent appliance cycles, weather related moisture, cable movement or a deteriorating connection. A written log helps diagnosis.

Safe checks you can make yourself

The following checks do not require tools or the removal of covers. Stop if you are unsure which switch controls which circuit, if the consumer unit is damaged, or if anyone in the property relies on electrically powered medical equipment.

Identify exactly which device has operated

Read the label beside the switch if it is clear. An RCD may protect several breakers and usually has a test button. An RCBO normally protects one labelled circuit. Photograph the consumer unit before moving switches so you have a record of their original positions.

Unplug portable appliances

Switch off and unplug portable appliances on the affected circuits. Remember items that are easy to overlook, including the dishwasher, washing machine, tumble dryer, fridge, freezer, boiler plug, outdoor equipment, extension leads and devices hidden behind furniture. Switching an appliance off at its controls may not disconnect every conductor, so unplug it where it is safe and accessible.

Reset once

With portable appliances unplugged, try one reset. Some RCD handles must be pushed fully down before they can be moved back to the on position. If it immediately trips again, do not repeatedly operate it.

Reconnect appliances one at a time

If the RCD remains on, reconnect appliances individually and allow enough time for each item to reach the stage at which the trip usually happens. Stop using an appliance that makes the RCD operate. Label it clearly so nobody else plugs it back in, and arrange appliance repair, replacement or testing.

Keep a fault log

Record the date, time, weather, affected circuits and what equipment was running. Note whether heating, hot water, outdoor lights or timed charging had just started. A short log can save considerable diagnostic time when the fault is intermittent.

What not to do when an RCD keeps tripping

• Do not hold the RCD in the on position or tape it up.
• Do not bypass the RCD or replace it with a device that offers less protection.
• Do not remove the consumer unit cover or disconnect conductors.
• Do not keep resetting it when there is heat, smoke, scorching, buzzing or a burning smell.
• Do not touch outdoor or indoor electrical equipment that is wet.
• Do not use an extension lead to restore a high load appliance from another circuit without professional advice.
• Do not assume a trip proves the RCD is faulty.
• Do not carry out insulation resistance or live testing unless you are trained, competent and using suitable equipment.

Why an RCD trips when nothing is plugged in

Nothing visible being plugged in does not mean the circuit has no connected equipment. Cookers, showers, immersion heaters, boilers, extractor fans, security lights, smoke alarms, garage supplies and garden circuits may be permanently connected. Fridges, freezers, routers and heating controls may also be hidden or forgotten.

The fault may also be in the fixed wiring. Damaged insulation, water inside an accessory, a neutral to earth fault or deterioration in an underground cable can operate the RCD with every portable appliance unplugged. At this point, continued DIY checks are unlikely to be useful. The circuits need electrical testing.

Why an RCD may trip but the circuit breakers stay on

An RCD responds to imbalance between live and neutral current. An MCB responds mainly to excessive current. A leakage fault can therefore trip the RCD while every individual circuit breaker remains in the on position. The fault current may be far below the level required to operate an MCB while still being high enough for a 30 mA RCD to disconnect.

If several circuits share that RCD, the affected breaker may not be obvious. An electrician separates and tests the circuits rather than assuming the fault belongs to the circuit that was in use when the power went off.

Why an RCD trips during rain or bad weather

Weather related tripping usually points towards equipment exposed to moisture. Outdoor lights and sockets are obvious candidates, but faults also occur in shed supplies, pond pumps, gates, hot tubs, garages, roof spaces and cables running through damp walls. An enclosure’s IP rating only protects it when it is suitable for the location, correctly installed, undamaged and properly sealed.

North East Scotland exposes outside equipment to driving rain, salt air, frost and repeated temperature changes. Water can travel along a cable or enter from behind an accessory, so the visibly wet fitting is not always the origin. The circuit should remain isolated until the fault has been located and repaired.

Why an RCD trips overnight

An overnight trip often follows an automatic schedule. Immersion heaters, storage heaters, EV chargers, dishwashers and washing machines may start on an off peak tariff. Fridges and freezers cycle throughout the night. Boilers, frost protection and exterior lighting can also operate without anyone pressing a switch.

Check timers and app histories where these are available, but do not repeatedly recreate the fault. Tell the electrician the tariff schedule and the approximate trip time. That information can narrow the investigation to equipment energised during that window.

Why an RCD trips when the oven or shower is used

Heating elements commonly develop insulation faults that become more apparent as they warm. An oven can therefore work when cold and trip after several minutes. Showers combine a large electrical load with water and must be treated cautiously. Stop using equipment that repeatedly trips the RCD and arrange testing.

A trip during high demand does not automatically mean the RCD is overloaded. A pure RCD has a current rating, but its protective trip function responds to residual current. If an RCBO or circuit breaker operates instead, overload or short circuit causes also need consideration.

How an electrician finds the fault

Professional fault finding follows evidence. We begin by confirming which protective device operates, which circuits it protects, when the fault occurs and what changed before it started. We inspect the consumer unit, labels, connections and accessible equipment for heat, damage, moisture and alterations.

The next steps depend on the installation and symptoms. Testing may include protective conductor continuity, insulation resistance, polarity, earth fault loop impedance, RCD operating time, RCD ramp testing and leakage current measurement. Circuits and connected equipment may need to be separated so that each can be tested without readings from other paths masking the result.

Insulation resistance testing helps identify unwanted current paths between live conductors and earth. Leakage current measurement shows what is happening while equipment is operating. RCD tests establish whether the protective device operates within the required parameters. No single test answers every case, which is why replacing parts without diagnosis can waste time and money.

Intermittent faults take longer to prove

A permanent fault is often present whenever the circuit is tested. An intermittent fault may depend on rain, vibration, temperature or a particular appliance cycle. The electrician may need to isolate sections, test equipment under controlled conditions, or return when the fault is active. A detailed fault log and photographs of the consumer unit after a trip are valuable.

Will an EICR find the cause

An Electrical Installation Condition Report assesses the condition and safety of the installation. It is broader than a targeted fault finding visit. If one RCD has suddenly started tripping, focused diagnosis is often the most efficient first appointment. If the property has widespread alterations, old wiring, no recent inspection or several unexplained problems, an EICR may also be appropriate.

The two services are related but not interchangeable. An EICR records the condition of the installation using an agreed inspection and testing scope. Fault finding follows a particular symptom until the cause is located as far as reasonably practicable. We will explain which approach suits the evidence rather than automatically selling both.

Does a tripping RCD mean the house needs rewired

Usually not. Many RCD trips are traced to one appliance, one damaged accessory, water ingress or a local cable fault. A rewire is considered only when testing shows that deterioration or unsafe alterations affect the installation more widely and local repair would not provide a sound result.

Age alone does not prove that wiring is unsafe. Electrical Safety First advises that an older consumer unit without modern features does not automatically require replacement. An EICR and targeted testing should determine condition rather than appearance or age by itself.

Would a new consumer unit stop the tripping

A new consumer unit will not repair a leaking appliance or damaged cable. Moving from shared RCD protection to individual RCBOs can limit disruption and reveal which circuit is affected, but the underlying fault still needs correction. Existing circuits must be tested as part of planning a consumer unit replacement.

An upgrade may be sensible when the existing board is damaged, lacks suitable protection, has poor circuit division, cannot accommodate planned work or is otherwise unsatisfactory. It should not be presented as a guaranteed cure before the fault has been investigated.

How often should the RCD test button be pressed

Use the interval stated on the consumer unit label and in the manufacturer’s instructions. Pressing the test button checks the device’s mechanical trip function and should disconnect the circuits it protects. It does not test the condition of the fixed wiring, prove that every socket is correctly connected, or replace professional testing.

If the test button does not make the RCD trip, arrange inspection. If anyone relies on medical equipment, alarms, refrigeration or other critical supplies, plan the interruption before carrying out a user test.

When the problem is urgent

Arrange urgent assistance when there is a burning smell, smoke, crackling, scorching, unusual heat, exposed live parts, repeated immediate tripping, electric shocks, flooding or water near the consumer unit. Keep people away and switch off the affected supply only if you can do so without approaching the hazard.

The HSE advises that people should be warned to stay away from an unsafe installation and that it should be switched off where this can be done safely. A competent electrical contractor should then assess it. If there is fire or immediate danger to life, call the emergency services.

RCD fault finding costs

The cost depends on how quickly the fault can be reproduced, how many circuits share the RCD, whether equipment must be disconnected, and whether the wiring is accessible. A faulty kettle can be identified quickly. A moisture dependent fault in an underground garden circuit or a neutral fault hidden among several altered circuits can require much more testing.

Faithful Spark explains the initial diagnostic charge before attending and discusses further work before carrying it out. The useful question is not only the hourly rate. Ask what testing is included, how findings will be recorded, whether repair work is included, and what happens if the fault is not present during the visit.

Real patterns we see across Aberdeen and Aberdeenshire

Across older Aberdeen flats, rural Aberdeenshire properties and coastal homes, the same patterns appear repeatedly. Outdoor fittings take in water after severe weather. Heating elements leak to earth only when hot. DIY alterations create crossed or shared neutrals. Rodents damage loft and outbuilding cables. Older split load boards allow one small fault to disconnect a large part of the property.

Local property construction also affects access. Granite walls, later extensions, converted steadings and detached outbuildings can hide several generations of wiring. The quickest diagnosis comes from combining test results with the history of the building and the timing of the trip.

Frequently asked questions

Can I leave an appliance unplugged and keep using the rest of the house

If one appliance consistently causes the trip and the RCD remains stable with that appliance unplugged, stop using and clearly label the appliance. Continue only if there are no other warning signs. Arrange repair or testing because the fault may worsen.

Can an RCD trip because too many appliances are on

An RCD normally trips because of residual current, not simply because total demand is high. Several appliances can contribute cumulative leakage, however. If an MCB or RCBO is the device operating, overload and short circuit causes also need to be considered.

Why will the RCD not stay up even with every breaker off

Possible causes include a neutral to earth fault, a fault before or around the RCD, conductors that remain connected despite the circuit breakers being off, or a defective RCD. Do not remove the cover. The installation needs testing.

Can a fridge or freezer trip an RCD

Yes. Compressor motors, defrost heaters, filters and damaged internal wiring can create leakage. Because refrigeration cycles automatically, the trip may seem random or happen overnight.

Can a faulty light bulb trip an RCD

A failed lamp more often operates a breaker or simply stops working, but a damaged fitting, LED driver, cable or damp external light can trip an RCD. The protective device and test results determine the likely fault type.

Why does the RCD trip after a power cut

Several appliances may restart together when power returns. One may be faulty, their combined leakage may be high, or a transient event may operate the device. If the problem repeats, unplug non essential appliances and arrange testing rather than assuming the network event is the only cause.

Can moisture cause an RCD to trip days after rain

Yes. Water may enter gradually, remain trapped, or move as temperature changes. The circuit can appear normal when dry and fail again during later weather. Outdoor equipment should be inspected and electrically tested before the circuit is relied upon.

Should I replace an RCD that keeps tripping

Only after testing. The RCD may be correctly disconnecting a dangerous fault. Replacing it without testing can leave that fault in place.

Is an occasional RCD trip normal

A one off operation can follow a transient event, but it still deserves attention to what was running. Repeated or unexplained trips are not normal and should be investigated.

Does turning a circuit breaker off isolate everything on that circuit

It may disconnect the live conductor but not necessarily the neutral. Safe isolation requires the correct procedure and suitable test equipment. Homeowners should not open the consumer unit or rely on a breaker position before touching wiring.

Who should investigate repeated RCD tripping

Use an electrician competent in inspection, testing and fault diagnosis. Ask how they will test the installation and verify their registration. Faithful Spark Electricians is a NICEIC Approved Contractor, enrolment number 620239, and Steven Watt holds City and Guilds 2391-52 in inspection and testing.

Book RCD fault finding in Aberdeen or Aberdeenshire

If your RCD keeps tripping and the safe checks above do not identify one faulty appliance, the next step is proper testing. Faithful Spark Electricians carries out electrical fault finding in Aberdeen, Peterhead, Ellon, Fraserburgh, Mintlaw, Balmedie, Westhill and surrounding areas.

Tell us which switch trips, when it happens, what was running and whether weather or recent work may be relevant. Photographs of the consumer unit and its circuit labels are helpful. Call 07304 027013 or request a written quote.

About the author

Steven Watt is the founder of Faithful Spark Electricians, an NICEIC Approved Contractor based in Peterhead and working across Aberdeen, Aberdeenshire and the wider North East of Scotland. He holds City and Guilds 2391-52 in inspection and testing, 2382-22 in the BS 7671 wiring regulations, 2365-03 in electrical installations and 2921-34 in electric vehicle charging installation, plus an HNC in Engineering Systems. Faithful Spark Electricians Ltd is TrustMark registered (licence 4205123), an OZEV approved installer (EVHS/WCS14254), an Aico Gold Standard installer and an Aberdeen Trusted Trader.

Faithful Spark Electricians | NICEIC Approved Contractor | Peterhead, Aberdeen and Aberdeenshire