Why Your RCD Keeps Tripping (And When to Worry)
By Frankie · February 2026 · 4 min read
It's one of the most common calls I get: "Frankie, my switch keeps tripping and I can't work out why." Usually it happens at the worst possible time — mid-shower, halfway through cooking dinner, or when you're working from home on a deadline.
The good news? Your electrics are actually doing exactly what they're supposed to. The bad news? Something's causing it, and it won't fix itself.
First — What's an RCD Actually Doing?
Think of your RCD like a very attentive bouncer at a nightclub. It's constantly monitoring the electricity flowing through your circuits, and if it detects even a tiny imbalance — a sign that current is leaking somewhere it shouldn't — it cuts the power in milliseconds.
That "leak" could be going through water, through faulty insulation, or worst case, through you. So when your RCD trips, it's not being annoying. It's potentially saving your life.
The Most Common Causes
In my experience, about 70% of tripping RCDs come down to one of these five things:
1. A Faulty Appliance
This is the number one culprit. Kettles, washing machines, dishwashers, and tumble dryers are the usual suspects. Over time, heating elements degrade and allow a tiny bit of current to leak to earth. Your RCD picks it up and trips. The appliance might seem to work perfectly fine, but inside it's slowly breaking down — like a car that drives fine but has a slow oil leak.
2. Moisture in an Outdoor Socket
If your RCD trips after heavy rain or when it's particularly damp, check your outdoor sockets, garden lights, or anything in an outbuilding. Water and electricity are not friends, and even a small amount of moisture in a connection can cause a trip.
3. A Worn-Out Immersion Heater or Shower Element
Electric showers and immersion heaters work incredibly hard. The heating element sits in water all day, every day. Eventually the protective coating breaks down and water gets where it shouldn't. If your RCD trips when you use the shower or hot water, this is likely the cause.
4. Old or Damaged Wiring
If your home was wired before the 1990s and hasn't been rewired, the insulation on your cables may be deteriorating. It dries out, cracks, and allows current to leak. This is a more serious issue and one I'd always recommend getting checked with an EICR.
5. The RCD Itself
Less common, but RCDs can become overly sensitive or develop faults as they age. If yours is more than 10-15 years old and trips for no apparent reason, it might be the unit itself rather than a fault on the circuit.
What You Can Try Before Calling Me
Here's a simple process that'll help you (and me, if you do end up calling) narrow it down:
The Unplug-and-Test Method:
1. Switch off and unplug everything on the affected circuit — appliances, lamps, chargers, the lot.
2. Reset the RCD. If it stays on, the fault is in one of the things you just unplugged.
3. Plug things back in one at a time. When the RCD trips again, you've found your culprit.
4. If the RCD trips with nothing plugged in, the fault is in the fixed wiring itself. That's when you need an electrician.
When Should You Actually Worry?
Most of the time, a tripping RCD is annoying but not dangerous — your protection is working. But there are a few situations where I'd say call an electrician sooner rather than later:
Call an electrician if:
⚠️ The RCD trips immediately every time you reset it
⚠️ You notice a burning smell or discolouration around sockets
⚠️ The RCD trips with nothing plugged in
⚠️ It trips randomly at night when nothing's being used
⚠️ You've got old wiring (pre-1990s) that's never been inspected
How Much Does It Cost to Fix?
If it's a faulty appliance, the fix costs you nothing — just unplug it and replace it. If it's something in the wiring, a diagnostic visit typically costs between £80-£150 depending on how tricky it is to track down. I always explain what I've found before doing any work, so there are no surprises.
If the RCD itself needs replacing, a quality unit is around £30-50 plus fitting. And if it turns out your wiring needs more attention, I'll talk you through your options honestly — including whether a full rewire or a consumer unit upgrade would be the smarter long-term investment.
The Bottom Line
A tripping RCD is your electrical system doing its job. Don't ignore it, don't keep forcing it back on, and don't be embarrassed to call — I get asked about this every single week.
And if you try the unplug-and-test method and find the culprit is your kettle, you don't even need me. Just buy a new kettle and save yourself the call-out fee. I'd rather you solved it yourself than paid me to tell you the same thing.
That's just how I work.
— Frankie, Bright Sparks of York
RCD Keeps Tripping?
If you've tried the steps above and it's still going, give me a ring. Free phone advice — I'll tell you if you actually need me or not.
Call: 01904 530 735Related Guides
The Complete Guide to EICRs — What they check and why they matter
Consumer Unit Upgrades — When your fuse board needs replacing
Electrical Safety Checklist — A room-by-room guide for your home