Get Your RCD tripping Sorted: Common RCD Issues With Fixes

My rcd tripping article is exactly what I would do If you hired me to resolve your tripping rcd problem. So read on, identify the problem and get your residual current device switched back on!

Switch the circuit breakers the rcd is protecting off (down). Now switch the rcd back on. If the rcd trips with every circuit breaker switched off then it’s likely a neutral to earth fault or a faulty rcd and that is a job for your local Cardiff electrician.

If the rcd trips when one circuit breaker is on; something on that circuit is faulty. Your rcd will hopefully reset after each circuit is isolated. I’ll show you how in this article.

I know that you already know an rcd is a device with a test button, but I want to show you a typical rcd consumer unit and point out what is what so you don’t go down the wrong road troubleshooting your tripping problem today.

Let’s get started…

The photo below contains two rcd units, six circuit breakers and the main switch – all inside a modern consumer unit. The rcds power the three circuits to the left of them. So the rcd inside the yellow section will only trip if a fault exists on circuits 1 (cooker), 2 (sockets first floor) and 3 (first-floor lights). Likewise, if the rcd tripped inside the green section it would be because of an earth fault on 4, 5 or 6.

A typical consumer unit with dual rcd protection

What you need to do if your RCD keeps tripping

Identify what the rcd is protecting and go through the process of elimination as to what is causing the trip. One challenge is not knowing what each circuit breaker does due to missing or incorrect labelling.

If that’s you right now, you need to work out what no longer works and make a list.

Quick checklist before switching tripped circuits back on….

Socket circuits can be problematic…

If sockets are being protected, unplug (not just switch off) everything – and re-try switching the rcd back on. It’s no good unplugging as much as you can leaving appliances that are hard to move or blocked in.

Some customers say they didn’t unplug something because it’s only a year old. Well, maybe the device is OK, but the wiring or socket-outlet it is using may have an issue and every time the device operates; causing your rcd trips. A socket circuit can be the most time consuming to diagnose because of all the unknown electrical accessories added to them.

Some things you may have wired in to your socket circuit causing an rcd tripping problem:

Could it be the lighting at fault?

If lights are protected by the tripping rcd then switch them off. If possible, remove the lamps (check they aren’t hot first). Circuit breakers are often labelled lights but can have other devices wired into them – like extractor fans in bathrooms. These can get contaminated from water and cause your rcd to trip. Hopefully, you have fan isolators that remove all conductors from them.

Pan boiled over, or have you cleaned your hob recently?

If you suspect your cooker circuit is causing rcd trips then look for big red switches that will remove the live and neutral from appliances, in the same way, unplugging a faulty device from a socket outlet would. Water can get inside the control gear and so can cleaning fluid.

Could it be your shower at fault?

A shower circuit can be isolated in the same way as cooking appliances. If you have any doubts if it’s a faulty appliance, then isolate it and re-try.

Kitchens are full of appliances (sometimes faulty)

For Kitchens: look in the cupboards. Yes, it can be a pain moving things, but you want that rcd switch back on right?! Some properties have no isolation other than directly behind the appliances. So, you might have to move a fridge or washing machine.

Central heating systems are full of water and need electric to work…

For suspected central heating system faults: there are often fused connection units (highlighted below) that will isolate the power supply for boilers and water heaters. Switch them off.

Fused connection units will remove the power supply from heating systems in the same way removing a plug would.
Take a look outside…

Do you have items outside? They can sometimes become contaminated with water. Wind can force rain in. Sometimes the tripping can be intermittent. If you think they are at fault: look for the isolation (often a fused spur in the bedroom).

Still not sure what is causing your rcd to trip? Here’s how you can tell

Turn all appliances sensitive to having the power removed suddenly, off. Things like computers and televisions.

Press the test button, or switch the rcd off (the one that usually trips). Make sure the (mcbs) circuit breakers haven’t tripped and are still in the on position.

Walk around and make a list of what no longer works. It’s worth spending some time making sure this is accurate; the list of things that do not work are being protected by the rcd and therefore at least one of them is the cause of your problem today.

Example rcd layouts to help visualise your problem

Bear aware that not every electrical circuit might cause your rcd trip.

If yours looks like the one below for example; the Residual Current Device is not powering all circuits. 1-6 (highlighted in red) are not protected. The circuits highlighted in green are. This was known to me when I took the cover off to investigate. I do not advise you as a home owner to do that, but you can come to the same conclusion by carrying out the exercise of switching the rcd off and making a list of what no longer works.

In the example below, all the lights were still working so I knew the lights in the house were not protected by rcd and therefore not causing an rcd trip in this instance.

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The consumer unit photographed below has one residual device (always identifiable by a test button). These are the hardest to troubleshoot because it could be any of the circuits (or a faulty appliance in this case) within the home. It can be a combination of more than one fault. By following this guide; the customer turned the shower isolator off and the rcd trip switch went back on. The faulty shower was replaced a few days later.

The consumer unit below is full of rcds, called rcbo’s. Whatever rcbo trips; just locate what no longer works and you know what is causing the problem. The rcbo for the cooker tripped so the customer knew there was an issue with the cooker, or its circuit. The wiring to the cooker tested OK. It was the cooker at fault. It was replaced and the rcbo went back on.

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Still can’t reset your rcd switch?

If you still have an rcd trip problem then I need to explain a few technical things to help you get it back on:

Remember I mentioned you needed to unplug everything when sockets are involved, not just switch it off? This is because rcds trip when the live and neutral conductors are imbalanced. Some socket outlets only remove the live when turned off – leaving the neutral still connected. John Ward, a qualified electrician explains why rcds can trip when the circuit has been switched off here:

Look for Fused connection units (which remove the live and neutral from accessories) like bathroom heating, central heating and outside accessories.

RCDs trip when they see an imbalance of appropriately 30 milliamps of current. The more items one protects; the more current is likely to be leaking. With this in mind, it can be a red herring for people when investigating tripping problems without the test gear electricians carry. If you turned the kettle on and the rcd trips; you would understandably believe there is a fault with the kettle. But, it could be you have two faults; you could have a leak on the oven and a leak on the kettle. When both in use it is enough to trip the rcd but not when used by themselves.

How to troubleshoot intermittent rcd trips issues (the most difficult)
  • Extractor fans. Some models run on after the light is turned off. Wind can blow water in through vents cause tripping issues.
  • Floodlamps. Maybe it hasn’t worked for a long time, but if it’s still got power going to it; it could well cause rcd problems when the winter comes.
  • Hobs and ovens. Sometimes cleaning products can get in to elements and the control gear. I’ve seen an rcd flip off because a pan boiled over causing a short in the igniter.
  • Rarely used appliances. Does your tripping have any type of pattern? Could it be whenever you use a certain appliance only used for parties or at Christmas for example?
  • Immersion heater. If you wake up in the morning with the Residual Current Device in the off position it be your water heater has a short circuit.
  • Outdoor equipment. Electrical items outside get damp and break down over time. If you don’t use them all year round; perhaps they could be causing an issue? Some items I can think of include pond pumps, patio heaters and summer house heating.

Intermittent tripping is the most difficult to diagnose. Sometimes electricians cannot find a fault whilst on site. Even thou the rcd has tripped that day.

RCD trip headache still going on? Here are some things to think about

When did the tripping first happen? What happened around that time – if anything? Have a good think as it may lead you / your electrician to the problem. Here’s some common causes of tripping:

  • Shelves being mounted on the wall.
  • Fixing your TV to the wall
  • New skirting boards.
  • New kitchen cupboards
  • An item that stopped working
How will a professional electrician get your rcd switched back on?

All electricians have fault finding techniques for residual current devices of their own. The first thing I do is check earth leakage with a clamp meter. When clamped on the meter tails it measures the imbalance exactly the same way your rcd does.

I remove power to circuits exactly the same way you did following this guide. Sometimes the amount of leakage does not change when the breakers are turned off. When this happens it’s because there is a neutral to ground fault. This is the very reason I asked you at the the start of this guide to unplug everything. Switching sockets off by the switch sometimes only removes the live, not the neutral. Electricians call this single-pole switching. So, if your washing machine has a neutral to ground fault causing the rcd to trip you might have missed that if you didn’t unplug it.

Hopefully my rcd tripping troubleshooters guide has helped get your rcd switched back on. If it hasn’t, maybe it’s helped you at least pinpoint the problematic circuit so your time hasn’t been wasted when you speak with an electrician.

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