If your RCD keeps tripping, it can be frustrating — particularly when it cuts power to several circuits at once.
But an RCD doesn’t normally trip for no reason. Repeated tripping can indicate a fault with an appliance, damaged wiring, moisture getting into electrical equipment or another problem that needs investigating.
In this guide, we’ll explain what an RCD does, the common reasons an RCD keeps tripping, what you can safely check yourself and when it’s time to call an electrician.
What is an RCD and what does it do?
An RCD (Residual Current Device) is a safety device designed to disconnect the electricity supply when it detects current flowing somewhere it shouldn’t.
In simple terms, it compares the electrical current flowing through the live and neutral conductors. If it detects an imbalance that could indicate current leaking to earth, it can disconnect the supply very quickly.
RCD protection is an important part of electrical safety in modern UK homes. Depending on the installation, one RCD may protect several circuits, or individual circuits may have their own RCBO protection.
This is why an RCD tripping can sometimes switch off several areas of your home at the same time
Why does my RCD keep tripping?
If an RCD keeps tripping, there are several possible causes. Some are relatively straightforward, such as a faulty appliance, while others require proper electrical testing to identify.
Common causes include:
- A faulty appliance
- Damage to electrical wiring
- Moisture or water getting into outdoor electrical equipment
- A fault on a socket or other electrical accessory
- Problems with an immersion heater, boiler or heating equipment
- Several appliances contributing small amounts of earth leakage
- A fault with the RCD itself
The fact that an RCD can be reset doesn’t necessarily mean the underlying problem has disappeared. If it repeatedly trips, the cause should be identified rather than simply resetting it each time.
Common reasons an RCD keeps tripping
1. A faulty appliance
One of the most common causes is an appliance developing an electrical fault.
Washing machines, dishwashers, kettles, tumble dryers and other appliances can develop insulation faults or allow small amounts of current to leak to earth. Heating elements are another potential source of faults.
If the RCD consistently trips when one particular appliance is switched on or starts operating, that appliance may need to be checked.
Don’t continue using an appliance if you suspect it has an electrical fault.
2. Moisture or water
If your RCD keeps tripping when it rains, moisture should be considered as a possible cause.
Outdoor sockets, lights, junction boxes, pond equipment and other external electrical equipment are exposed to much harsher conditions than equipment inside the home.
Water ingress or condensation can result in leakage to earth and cause RCD protection to operate.
If the problem appears during or after wet weather, mention this to your electrician — it can be a useful clue when tracing the fault.
3. A wiring fault
Damage or deterioration within the fixed wiring can also cause an RCD to trip.
Possible causes include damaged cables, deteriorated insulation, faults at electrical accessories or problems caused by previous electrical work.
These aren’t faults a homeowner should attempt to locate by removing sockets, switches or consumer unit covers. Proper electrical test equipment may be needed to identify the problem safely.
4. Heating equipment
Immersion heaters, electric showers, boilers and other equipment containing heating elements can sometimes develop insulation faults.
The fault may also appear only once the equipment heats up, which can make intermittent RCD tripping more difficult to diagnose.
5. Outdoor electrical equipment
Garden lighting, outdoor sockets, pumps, hot tubs and other external equipment can all contribute to RCD problems.
Damage from weather, deterioration, water ingress or damaged cables can cause electrical leakage.
If you suspect outdoor equipment, don’t dismantle it yourself. An electrician can safely isolate and test the relevant circuit and equipment.
6. Too much combined earth leakage
Sometimes there isn’t one obvious major fault.
Modern homes contain increasing numbers of electronic devices, each of which can contribute a small amount of normal leakage current. When several circuits or appliances are protected by the same RCD, the combined leakage can potentially contribute to unwanted tripping.
An electrician can measure leakage current and determine whether the installation or circuit arrangement needs further investigation.
7. The RCD itself
RCDs can also develop faults or deteriorate with age.
However, don’t assume the RCD is faulty simply because it keeps tripping. Its job is to disconnect the supply when it detects certain fault conditions, so repeated operation may mean it is doing exactly what it was designed to do.
An electrician can test the RCD’s operation and determine whether the device itself needs replacing.
What can you safely check yourself?
There are a few simple observations homeowners can make without carrying out electrical work.
You can:
- Note what was being used immediately before the RCD tripped.
- Check whether the problem occurs when a particular appliance is used.
- Look for obvious external damage to appliance plugs, leads and accessible electrical equipment.
- Notice whether tripping happens during or after heavy rain.
- Stop using an appliance if it appears to trigger the problem.
- Make a note of how frequently the RCD trips and which parts of the house lose power.
This information can be extremely useful to an electrician trying to locate an intermittent fault.
Don’t remove electrical covers, open the consumer unit, dismantle sockets or switches, or attempt electrical testing yourself.
If there are signs of burning, overheating, smoke, arcing, exposed live parts or another immediate electrical danger, don’t continue trying to reset the supply. Keep clear and seek professional help.
Should I keep resetting an RCD that trips?
An occasional trip associated with an obvious temporary event is different from an RCD that repeatedly operates.
If it resets but then trips again, particularly without an obvious explanation, don’t simply keep resetting it indefinitely.
Repeated tripping is a warning that something needs investigating.
Electrical Safety First advises that if an RCD keeps switching off, there is likely to be a fault with an appliance or the wiring that should be investigated by a registered electrician.
Why does my RCD trip when it rains?
If an RCD tends to trip during or shortly after wet weather, outdoor electrical equipment is one of the areas an electrician may investigate.
Potential sources can include:
- Outdoor sockets
- Garden lighting
- Security lights
- External junction boxes
- Pond pumps
- Hot tubs
- Electric gates
- Outdoor heating
- Cables supplying sheds, garages or garden buildings
Water ingress isn’t always obvious from the outside. An accessory can appear perfectly normal while moisture has entered internally.
Don’t remove covers or attempt to dry out electrical equipment yourself. If there’s a clear relationship between rain and the RCD tripping, tell the electrician investigating the fault.
Why does my RCD trip at night?
An RCD that appears to trip overnight can be particularly confusing because nobody may be actively using anything.
However, many electrical appliances operate automatically.
Possible examples include:
- Fridges and freezers
- Boilers and heating controls
- Immersion heaters
- Dishwashers or washing machines running overnight
- EV chargers
- Outdoor lighting
- Pumps
- Appliances controlled by timers
The timing can therefore provide an important clue.
For example, if the RCD regularly trips shortly after an EV starts charging overnight or when an outside light switches on, tell your electrician.
The timing alone doesn’t prove which appliance or circuit is responsible, but it can help considerably when tracing an intermittent fault.
RCD tripping: quick guide
| What you’re noticing | Possible area to investigate |
|---|---|
| Trips when one appliance is used | Appliance fault |
| Trips during or after rain | Outdoor equipment or moisture |
| Trips when heating comes on | Heating equipment or associated circuit |
| Trips overnight | Timed or automatically operating equipment |
| Trips apparently at random | Appliance, wiring or cumulative leakage |
| Won’t reset | Persistent fault requiring investigation |
| Trips again soon after resetting | Underlying fault may still be present |
Important: These are possible clues rather than diagnoses. Electrical testing may be required to establish the actual cause.
When should I call an electrician?
Arrange for an electrician to investigate if:
- The RCD repeatedly trips.
- It won’t reset.
- It trips again shortly after being reset.
- You can’t identify an obvious appliance associated with the problem.
- Tripping occurs during wet weather.
- There are signs of burning, overheating or electrical damage.
- You suspect a problem with the fixed wiring.
- You’re simply unsure whether the installation is safe.
A registered electrician can carry out appropriate testing to identify whether the problem relates to an appliance, a particular circuit, the fixed wiring, accumulated leakage or the protective device itself.
For electrical work in your home, you can use the Electrical Safety First Registered Electrician search to help find a suitably registered contractor.
Could my consumer unit be the problem?
Possibly, but repeated RCD tripping doesn’t automatically mean you need a new consumer unit.
The protective device itself can be tested, and the arrangement of circuits and RCD protection may form part of an electrician’s investigation.
Older installations can also have different arrangements from modern consumer units, so the cause needs to be established before recommending replacement work.
Frequently asked questions
Why does my RCD keep tripping with nothing plugged in?
Unplugging portable appliances doesn’t necessarily remove every possible cause. Fixed appliances, heating equipment, outdoor equipment and faults within the electrical installation may still be connected.
If the RCD continues to trip and there isn’t an obvious cause, have the installation investigated by an electrician.
Can a faulty appliance trip an RCD?
Yes. An appliance with an electrical fault or excessive leakage to earth can cause RCD protection to operate.
If one appliance consistently appears to trigger the problem, stop using it until it has been appropriately checked.
Can rain cause an RCD to trip?
Rain itself isn’t causing the RCD to malfunction. However, moisture entering outdoor electrical equipment or damaged accessories can create an electrical fault that causes the RCD to operate.
Why does my RCD trip but the circuit breakers don’t?
RCDs and circuit breakers provide protection against different types of electrical fault.
A conventional circuit breaker primarily protects against overcurrent conditions such as overloads and short circuits, whereas an RCD responds to an imbalance associated with current leaking from its intended path.
It’s therefore possible for an RCD to operate without an individual circuit breaker tripping.
Can I replace an RCD myself?
Work inside a consumer unit isn’t an appropriate DIY job. It involves potentially dangerous electrical equipment and requires appropriate testing after work is carried out.
Have consumer unit work undertaken by a suitably qualified and competent person.
Is an RCD that keeps tripping dangerous?
Repeated tripping shouldn’t be ignored. The RCD is a protective device, and its operation may indicate an electrical fault.
The safest approach is to have persistent or unexplained tripping investigated rather than repeatedly resetting the device.
The bottom line
If your RCD keeps tripping, don’t assume the RCD itself is the problem.
Faulty appliances, moisture, outdoor electrical equipment, heating equipment and faults within the electrical installation are among the possible causes.
There are useful observations you can make — such as what was operating when the power went off or whether the problem coincides with wet weather — but electrical fault-finding should be left to someone with the appropriate competence and test equipment.
An RCD is there to protect you. If it repeatedly operates, finding out why is more important than simply getting the power back on.
If you’re reviewing the general condition of your home’s electrics, read our guide to 7 Electrical Safety Checks Every Homeowner Should Know.
Important: This guide provides general information for UK homeowners and isn’t a substitute for an assessment of your individual electrical installation. Electrical faults should be investigated by a suitably qualified and competent person.