Why Does My RCD Keep Tripping — And How Do I Stop It?

What exactly is an RCD and why does it keep switching off my power?

If your electricity keeps cutting out suddenly, there’s a good chance your RCD (Residual Current Device) is doing its job. It's there to protect you from electric shocks and potential electrical fires by switching off the power if it detects leakage current — that is, when electricity flows somewhere it shouldn’t, like into a person or water.

An RCD is usually found in your fuse box (also called a consumer unit), and it monitors the flow of electric current between the live and neutral wires. If there’s even a small mismatch, it trips.

You might also hear people call it a safety switch. And while it can be annoying when it keeps tripping, it's often a sign that something isn't quite right. The good news? It’s not always serious — but it does need attention.

Why does my RCD keep tripping — and what could be causing it?

There are a few usual suspects when it comes to a tripping RCD. Some are simple fixes; others may need a qualified electrician to sort out.

Faulty appliances are the most common cause. Think kettles, fridges, washing machines — anything that plugs in. If there’s a fault in the electrical insulation or wiring, it can leak current to earth and trip the switch.
Overloaded circuits can also be to blame. If you’re running too many things off one circuit, especially appliances with heating elements, the load might be too high.
Moisture is another big one. A splash of water in the wrong place — like an outside socket or bathroom fitting — can cause your RCD to trip immediately.
Damaged extension leads or DIY electrical work that wasn’t done quite right can trigger earth leakage too.
And finally, rodents chewing through wires or ageing wiring insulation can lead to intermittent faults that make the RCD trip every so often.

All of these situations can result in nuisance tripping, which is your RCD being overly sensitive due to a lingering small fault or a slightly overworked system.

How can I find out what’s causing my RCD to trip?

Start by turning everything off and then back on one at a time. Here’s a simple step-by-step to help you test safely:

Switch off all appliances and unplug them if you can.
Reset the RCD on your fuse box.
Turn circuits on one at a time, then plug in your appliances one by one.
When the RCD trips again, you’ve likely found your culprit.

This is a process known as circuit isolation. A multimeter can be useful if you know how to use one, but if in doubt, leave that to the professionals.

Always check things like extension leads, older appliances, or anything that’s been exposed to damp conditions. It’s usually one item or one circuit that causes the problem. A faulty socket outlet or lighting circuit could also be to blame.

Remember, the test button on your RCD should be pressed every few months to check it’s working properly — it simulates a fault to see if the RCD trips.

Which appliances are most likely to trip an RCD?

Some appliances are more prone to tripping your RCD than others — usually because they use a lot of electricity or involve water.

Fridges and freezers can cause problems if their compressors are failing.
Kettles, toasters, and irons have heating elements that wear out over time and may leak electricity.
Washing machines and dishwashers are high on the list too — they combine water and electrics, and that’s a risky mix.
Electric showers and immersion heaters are also common culprits.
Outdoor tools, like lawnmowers or pressure washers, especially if they’ve been stored in a shed and picked up some moisture, can trip the RCD instantly.

What these appliances have in common is that they either draw a high current, are exposed to water, or both. If one of these is tripping your RCD, it’s worth having it checked or replaced.

When should I stop troubleshooting and call an electrician?

If the RCD keeps tripping randomly, you’ve unplugged everything, reset everything, and you still can’t find the cause — it’s time to get a licensed electrician involved.

Also call an expert if:

You notice burning smells, buzzing sounds, or flickering lights
The RCD won’t reset at all
The issue keeps coming back, even after you’ve isolated the appliance
You’ve had DIY electrical work done recently

A professional will carry out an electrical inspection, use tools like an insulation resistance tester, and provide a safety certificate if needed. They’ll also check your home’s earthing system, which is key in preventing electric shocks.

How can I stop my RCD from tripping in the future?

There are a few things you can do to help keep your system stable:

Don’t overload sockets. Spread out high-use appliances across different circuits.
Use surge protection plugs or power boards — especially for computers or entertainment systems.
Keep electrical appliances dry, and don’t use indoor ones outside.
Book a periodic inspection report every 5–10 years, or sooner if your home is older.
If you’ve had any water leaks, make sure no electrical components have been affected.

You might also consider upgrading to RCBOs, which protect individual circuits, instead of a single RCD that trips the whole house.

Think of your RCD like a smoke alarm. It’s better it trips once too often than not at all. But with a few checks and good habits, you’ll reduce how often it kicks in.

Why won’t my RCD reset — and should I be worried?

If your RCD won’t stay on, even after you’ve unplugged everything, something bigger might be going on.

This can happen if:

There’s a fault in the wiring itself
A neutral wire is touching earth somewhere
The RCD unit is faulty and needs replacing
A hidden issue, like a damp junction box in the loft, is shorting the circuit

Don’t force the RCD to stay on — this is a safety device. If it keeps tripping or won’t reset, get it looked at. It could prevent serious harm or damage.

Some people also ask whether a power cut can trip the RCD — and yes, occasionally when the power comes back on, the surge can cause a nuisance trip. If this happens regularly, it might be worth installing surge protection.

Final Thoughts

If your RCD keeps tripping, it’s trying to tell you something. Whether it’s a simple fix like an old kettle, or something more serious like faulty wiring, don’t ignore it.

Always start with appliance testing, use the test button, and try to isolate the fault. But if you’re not confident, or the problem won’t go away, speak to a qualified electrician. Better safe than sorry.

Did You Know?

Electrical Accidents at Work: The UK Health and Safety Executive (HSE) reports that approximately 1,000 workplace accidents involving electric shock or burns are reported annually, with around 30 of these being fatal. Safe Arc Solutions
RCD Reliability: Research by the Electrical Safety Council indicates that fixed RCDs have a reliability rate of about 97%, which improves with regular user testing. ddfire.gov.uk

Need a Trusted Electrician in London to Fix Your RCD?

If your RCD keeps tripping and you're not sure why — or you've tried everything and it's still happening — it might be time to bring in the professionals. At TNS Electrical Solutions, our emergency electricians specialise in fault finding, RCD repairs, and full electrical diagnostics across London.

We’re fully qualified, NICEIC-approved, and local to you — so whether it’s a one-off fault or part of a bigger issue, we’ll get it sorted safely and quickly.

Get in touch today:

Address: 445 Sulivan Ct, Peterborough Rd, London SW6 3BX
Phone: 020 3715 2919
Website: www.tnssolutions.co.uk
Email: info@tnssolutions.co.uk
Business Name: TNS Electrical Solutions

We’re here to help — fast response, fair prices, no fuss.

Frequently Asked Questions About RCD Tripping

How can I tell if my RCD is faulty?

If your RCD won’t reset, even after unplugging all appliances and switching off all circuit breakers, there’s a chance the device itself might be faulty. Another sign is if the test button no longer trips the switch — this test simulates a fault, so if pressing it does nothing, the RCD may not be working as it should. If you're unsure, a qualified electrician can run proper insulation resistance tests to confirm whether it needs replacing.

How do I find out what’s tripping my circuit breaker or RCD?

Start by switching off and unplugging everything connected to the circuit. Then reset the RCD or circuit breaker. Turn the breakers and appliances back on one at a time. If the RCD trips again after a certain item is reconnected, you’ve likely found the fault. This method is known as fault isolation. Sometimes it’s not the appliance itself but a damaged cable, overloaded socket, or damp outlet causing a residual current leak.

Why is my RCD tripping when nothing is plugged in?

Even if nothing is visibly plugged in, there could still be issues in the fixed wiring or hidden connections. For example, moisture in a junction box, a damaged cable in the wall, or a neutral-to-earth fault can all cause the RCD to trip. In some cases, outdoor lighting circuits or garden sockets may have taken in water and triggered the RCD, even if the items are turned off. These kinds of faults can be tricky to spot without proper testing tools.

Do RCDs need to be replaced?

Yes, like any electrical safety device, RCDs can wear out over time and may eventually stop working correctly. If your RCD trips frequently without clear reason, fails the test button, or shows signs of damage (like a buzzing sound or heat), it may need replacing. Electricians recommend testing your RCD every three months and having it checked during regular electrical inspections, especially in older homes.