Home › Electrical › RCD Keeps Tripping

ELECTRICAL FAULT GUIDE

RCD Keeps Tripping

An RCD usually trips because current is leaking to earth through a faulty appliance, damaged cable, wet outdoor equipment or a fault in the fixed wiring. This guide helps you narrow down the cause using safe, non-invasive checks.

!

Stop immediately if there is heat, burning, arcing or water near electrics

Do not remove the consumer-unit cover, open sockets, test exposed conductors or repeatedly force the RCD back on. If it trips with all protected circuit breakers off, or there are signs of damage, call a registered electrician.

MOST LIKELY CAUSES

Start with these

Most repeated RCD trips are caused by an appliance fault, moisture, outdoor equipment or a fault affecting one of the protected circuits.

Faulty appliance Heating elements, pumps, motors and mains filters are frequent offenders.
Outdoor moisture Outside sockets, lights, pond equipment and extension leads may take in water.
Fixed wiring fault Damaged cable, loose connections or insulation breakdown need proper testing.
Several small leakage currents Multiple connected appliances can combine and push the RCD beyond its trip threshold.
◫ Symptom variations Match when and how the RCD trips. ⌄
  • Trips immediately when reset: a fault is still connected or present on the protected circuits.
  • Trips when one appliance starts: suspect that appliance, its plug, lead or connected outlet.
  • Trips after several minutes: a heating element, motor or moisture-related fault may appear as the equipment warms up.
  • Trips during rain: inspect outdoor sockets, lights, sheds, pumps and weather-exposed connections.
  • Trips overnight: check timed appliances, boilers, immersion heaters, fridge/freezers and outdoor equipment.
  • Trips apparently at random: intermittent appliance faults, water ingress and cumulative leakage are common possibilities.
✓ Quick checks Safe checks that do not require opening electrical accessories. ⌄
  1. Look at the consumer unit and confirm that it is the RCD, not only one circuit breaker, that has tripped.
  2. Note which circuit breakers sit beside or underneath the affected RCD.
  3. Unplug portable appliances on those circuits. Switching them off at the socket may not fully disconnect every conductor.
  4. Remember hidden loads: washing machine, dishwasher, fridge, boiler, immersion heater, outside equipment, garage and shed supplies.
  5. Check for recent rain, leaks, cleaning, building work or a newly connected appliance.
  6. Move the RCD fully to the OFF position, then reset it once.
If it stays on: reconnect appliances one at a time and wait long enough for each appliance to begin its normal operating cycle.
If it trips again with appliances unplugged: stop. A permanently connected load or fixed-wiring fault is likely and needs electrical testing.
1 Fix 1 — Find a faulty portable appliance The safest useful test for a householder. ⌄

Tools needed

None. A phone or notepad helps record what has been disconnected.

Process

  1. Unplug appliances on the affected circuits.
  2. Reset the RCD once.
  3. Reconnect one appliance.
  4. Switch it on and allow it to reach the stage where it normally heats, pumps, spins or starts a motor.
  5. Continue one appliance at a time until the RCD trips.
Success looks like: the RCD remains on until one particular appliance is connected or begins operating.
Failure means: if the RCD trips with everything unplugged, the fault may involve fixed equipment or wiring.

What to do next

Leave the suspected appliance unplugged. Have it repaired, electrically tested or replaced. Do not keep using it through another socket.

2 Fix 2 — Check outdoor and damp-area equipment Especially relevant after rain or cleaning. ⌄

Check without dismantling

  • Outdoor sockets and extension leads
  • Garden lights and transformers
  • Pond pumps and water features
  • Shed and garage equipment
  • Pressure washers and lawn equipment
  • Appliances near sinks, utility rooms and leaking pipework

Disconnect portable outdoor equipment and allow clearly wet plugs or leads to remain unused. Do not open sealed fittings or energise equipment merely to “dry it out”.

Success looks like: the RCD remains on after the wet or suspect equipment is disconnected.
Failure means: a fixed outdoor circuit or hidden connection may be affected and needs insulation-resistance testing.
3 Fix 3 — Narrow down the affected circuit Only use the front controls of the consumer unit. ⌄

This check can help identify which circuit needs professional testing. Do not remove any consumer-unit covers.

  1. Turn off the circuit breakers protected by the tripping RCD.
  2. Reset the RCD.
  3. Turn the circuit breakers back on one at a time.
  4. Stop when the RCD trips.
Useful result: one circuit repeatedly causes the RCD to trip when switched on.
Important: this identifies a circuit, not the exact fault. Leave that circuit off and arrange testing.

If you are unsure which devices protect which circuits, or the labelling is poor, do not experiment. Call an electrician.

⌁ Common causes explained Why an RCD may trip even without an obvious short circuit. ⌄

Heating elements

Washing machines, dishwashers, ovens and immersion heaters may only leak current when the element becomes hot, so the trip can be delayed.

Motors and pumps

Worn insulation, moisture or winding faults in pumps, compressors and motors can produce intermittent leakage.

Electronic equipment

Mains filters naturally create a small amount of earth leakage. Several appliances on one RCD can combine, leaving little margin before it trips.

Water ingress

Outdoor fittings, damaged seals and condensation can lower insulation resistance and cause trips during wet weather.

Neutral-to-earth faults

A connection or insulation fault between neutral and earth can cause difficult, apparently random tripping and requires proper testing.

⌘ Advanced diagnostics Technician-level testing for a competent electrician. ⌄

These checks require suitable test instruments, safe isolation and competence. They are not DIY live-testing instructions.

  • Confirm RCD type, rating, mechanical operation and trip-test results.
  • Measure individual circuit leakage using a suitable leakage clamp meter.
  • Carry out insulation-resistance testing with sensitive equipment disconnected as required.
  • Check for neutral-to-earth faults and borrowed neutrals.
  • Test permanently connected appliances individually.
  • Inspect outdoor wiring, junctions and accessories for water ingress.
  • Verify circuit division and cumulative protective-conductor current.
  • Replace the RCD only after proving that the device itself is defective.
◇ Tools needed Householder checks versus professional testing. ⌄

For safe basic checks

  • Phone or notepad
  • Torch
  • Known-good small appliance or lamp, where appropriate

For a competent electrician

  • Approved voltage indicator and proving unit
  • Multifunction installation tester
  • Leakage clamp meter
  • Insulation-resistance tester
  • RCD tester
  • Suitable insulated tools and PPE
▣ Parts that may need replacing Common failed components linked to repeated trips. ⌄
  • Faulty appliance heating element
  • Appliance pump, motor or compressor
  • Damaged appliance mains filter
  • Outdoor socket, light fitting or junction enclosure
  • Damaged cable or accessory
  • Faulty permanently connected appliance
  • RCD or RCBO, but only after testing proves device failure
! When to call an electrician Conditions that should end DIY troubleshooting. ⌄
  • The RCD trips with all portable appliances unplugged.
  • It trips with all protected circuit breakers switched off.
  • There is burning, buzzing, crackling, heat or visible damage.
  • Water has reached sockets, lights, the consumer unit or fixed equipment.
  • The consumer unit is damaged, poorly labelled or has exposed parts.
  • The fault affects a shower, cooker, immersion heater, boiler or outdoor circuit.
  • The RCD will not reset or does not operate using its test button.
  • The trip returns repeatedly and no appliance can be identified.

Electrical Safety First advises that an RCD which keeps tripping is likely to indicate an appliance or wiring fault that should be investigated by a registered electrician.

? Frequently asked questions Common questions about repeated RCD trips. ⌄

Can I keep resetting the RCD?

No. One controlled reset may help establish whether the fault remains. Repeatedly resetting it without finding the cause is not a repair.

Can one appliance switch off several rooms?

Yes. One RCD may protect several separate circuits, so a fault on one appliance can disconnect multiple rooms.

Why does it trip only when the washing machine heats?

A damaged heating element may leak current only after it becomes hot.

Does an RCD trip mean the RCD itself is faulty?

Usually not. The device is often responding correctly to leakage elsewhere. Testing is needed before replacing it.

Why does it trip when it rains?

Moisture may be entering an outdoor accessory, cable joint, light, shed supply or garden appliance.

Safety references

Electrical Safety First: If my RCD keeps tripping, what action is required?

Health and Safety Executive: Electrical safety FAQs

RCD protection reduces risk but does not make electrical work safe by itself.