Boiler Tripping RCD: Why?

As usual, being a homeowner is great… right up until something goes wrong. Yesterday it was your taps not working, today it’s your builder tripping the RCD, and tomorrow, who knows? Luckily, DreamyHome is the residence of some very knowledgeable people who can help out! If your boiler is continually tripping your RCD, you came to the right place to figure out why – and get it fixed.

The most common causes of a boiler tripping the RCD are a water leak, condensation, poor insulation, or damaged wiring – though there are more to talk about.

Now let’s get into it, shall we?

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Boiler Tripping RCD: Troubleshooting

Now, a forewarning – many of these issues aren’t things you can deal with yourself. If there is a fix you can do at home, we will tell you about it. But with things like this, it’s often best to let the professionals do their jobs and just watch from the sidelines. Troubleshooting will be a massive help to them in the first place, so you can rest assured that you did, in fact, help.

Wall Socket

This should be one of your first checks. The electric socket that you’ve got the water tank plugged into needs to be in tippy-top condition. If you notice cracks or worse, melted bits, it’s time to call a professional. It’s likely that you’ll need to replace the socket and (maybe) the water heater’s cable.

This isn’t something to ignore – it’s dangerous and should be treated as such. Plus, you won’t get hot water until it’s dealt with.

Water Leaks in the Boiler

Whether it’s due to corrosion, warping, busted pump seals, or high pressure, this isn’t something to mess around with. Not only is water damage a pain to deal with, but when paired with electricity, it can get downright dangerous. When inspecting your boiler, take a look at these common problem areas:

  • The pump seals
    • Specifically, you’re looking for loose or damaged seals. Another obvious sing is, well, water leaking out from the seals.
  • Flue (the pipe/chimney that removes gases from your boiler to your home’s exterior)
  • Insulation
    • Check the insulation between the flue and exterior of your boiler first, and check all remaining insulation second.
  • Wiring
    • Look at the wiring between the boiler and exterior. You’re looking for leaks reaching the wires, as well as clearly damaged or frayed wiring.
  • And the obvious one – the area around your boiler. Water on the ground is not good.

If you suspect that your boiler may be leaking, it’s best to call a professional for an assessment. While you may spot the leak, it’s entirely possible that it’s an internal leak, which really needs a pro’s eyes to double-check.


Especially if you live in a cold, rainy environment (like the UK), this is a common issue. Take a look at your flue and the area around your boiler for condensation. If you notice moisture in the flue, it’s very likely that your RCD switched itself off when it detected moisture.

If this is the case, you’ll likely need to replace multiple parts of your boiler. Again, I recommend that you call a professional for help and measurement that it is, indeed, the issue. It would suck to replace all of the parts you think are the problem, only to not fix the issue.

Damaged Wiring & Insulation

Remember how I said to take a look at the wiring and insulation of your boiler? Yeah, this is a common component that goes bad. If any part of your boiler is opened to moisture due to damaged insulation or wires that have frayed, you have a few issues. First, that’s a fire hazard. Second, your RCD is likely tripping to prevent further damage.

Faulty Heating Elements

Locate the safety cover on the bottom of your boiler (it could be elsewhere, but they’re generally on the bottom). Pop it off using a screwdriver and you’ll see the boiler’s heating elements. These will be one of two types of heating elements – immersed (sits inside the tank), or covered (no contact with water).

Immersion elements are more likely to have faults due to limescale buildup. In time, the limescale can damage the element’s internal bits, tripping the fusebox. They’re supposed to have insulation, but over time it can wear away.

Covered elements, on the other hand, should not come into contact with water. However, the screws that hold them in place can come into contact with water, leading to corrosion and even breakage. If you notice that your covered element is leaning, it’s likely that you’ll need to replace the screw. To test this, disconnect the heating element and turn the power back on. If it powers up without tripping the RCD, that was your cause.

You can also use a multimeter to test both of these. Turn off water to the heater and test the elements – if a value is displayed, there’s a leak and the element will need to be replaced by a professional.

Final Thoughts

Having issues with a boiler is never fun. Not only are they rather finicky machines, but there’s a lot that goes into making them work. And when even a single piece stops working, the whole thing will stop as well. If you’re noticing that your boiler is tripping your RCD, go through the list above. Begin by checking your wall socket, and then move on to looking for leaks and condensation. A damaged wall socket or water leaking anywhere is a sign that it’s time for a pro to take a look.

If neither of those is the cause, take a look at the wiring and insulation and inspect the heating elements. If you noticed damaged or warped insulation, frayed wiring, or issues with a heating element, call for help. These are all serious issues that should have a professional assessment – there’s no sense in messing with electricity and water in your home. Not only could it be dangerous, but it’s a pain to deal with if you don’t know what you’re doing.