RCD Tripping in Cardiff? Gabe Electrical Are Here to Help.

Is your RCD tripping? Cardiff-based Gabe Electrical is here to help. Whether it’s a one-off trip, recurring nuisance tripping, or the RCD has now stayed in the tripped position — causing a partial loss of power — this article will help you identify the cause and walk you through restoring it. If you’ve lost all power instead, please refer to our power-cut article. Otherwise, this guide will help you identify common causes and solutions and gather information we would need to assist you should the fault require our attention.

The RCD protects circuits to the left or right of it, depending on the layout. Switch the circuit breakers that the RCD is protecting to the off position (down). Now, try switching the RCD on. If it trips straight away, it’s likely you’ll need an electrician to investigate. This is because circuit breakers disconnect the live wire but not the neutral. Fixing faults like this requires knowledge of the installation and test gear, which an electrician carries.

If the RCD stays on by itself, give it a minute or two to be sure, and press the test button. It should trip. If it doesn’t, the RCD may be faulty, or there may be a fault in the system—another job for an electrician.

If the RCD stays on for a minute, try switching one circuit breaker on at a time. Your goal is to narrow the fault down to one circuit. For example, if you turn the light circuit breaker on and the RCD stays on, go around the house and switch all the lights on and off a few times. If they all work without causing the RCD to trip, it’s a good sign that the lighting circuit isn’t the issue. You can then switch the light circuit breaker off and try the next one.

For appliances like cookers and showers, simulate actual usage—it’s not enough that the clock comes on.
When you get to the sockets, ensure all appliances are unplugged. It’s a hassle, but you want to get the power back on, right? Simply switching off appliances isn’t always effective because some sockets are single-pole, meaning they only disconnect the live wire while the neutral remains connected.

Not all consumer units are labelled clearly or correctly. Sometimes, changes have been made that make the labelling inaccurate. For example, a circuit breaker labelled “Alarm” could now be controlling an outside light.
To work out what each circuit breaker controls, make a list of what powers what and update the labels on the consumer unit.

Here are some common setups:

6 or 10 amp circuit protection typically covers lights, smoke detectors, alarms, extractor fans.
16 or 20 amp circuit protection may be for central heating systems or water cylinders.
30 or 32 amp circuit protection could be for socket outlets or cooker supplies.
40 or 50 amp circuit protection is usually for modern showers, induction hobs, electric vehicle charging points, or supplies to detached buildings.

It’s worth noting that just because a circuit is labelled one thing, it doesn’t mean it powers only that. For instance, lighting circuits may also power smoke detectors, and socket circuits could have fused spurs that power outside lights or underfloor heating.
Determining what powers what can involve walking around with a pen and paper, noting down which circuit breaker powers which items. For example, if your underfloor bathroom heating is causing the tripping today, it could have its own circuit if the house has been rewired. But it might also be part of a socket circuit with a fused spur inside a cupboard on the landing.

The aim of this process is to isolate the problem. Troubleshooting RCD tripping can be time-consuming, but if you’ve followed these steps and the RCD still won’t stay on, you haven’t wasted your time. When you contact an electrician, you’ll be able to explain what you’ve done to isolate the issue.

Intermittent RCD trips are the hardest to diagnose, as the fault may not always be present during testing. It’s worth giving it some thought—perhaps someone borrowed a faulty appliance, or the fault only occurs when a specific socket outlet is used.
If you’ve had enough of dealing with RCD tripping, contact us now for help.

What to Expect From Our RCD Fault-Finding Visit

When we arrive, we’ll listen to what you’ve already done to isolate the problem and work methodically to locate the issue. While RCDs can be faulty, it’s typically a fault in the system that causes them to trip. They usually perform their job correctly.

Another issue that can occur with RCD tripping is something called cumulative earth leakage. RCDs are designed to trip quickly to reduce the risk of electrocution. They work by detecting an imbalance between the live and neutral conductors. Some appliances, like heating elements in your oven, dishwasher, or water cylinder, leak a small amount of current by design. If you have many appliances all protected by a single RCD, the cumulative leakage can sometimes approach the tripping threshold.

This is something only an electrician with an earth leakage clamp can detect. It’s also one reason why we install consumer units with RCBO protection, where each circuit has its own RCD, rather than one RCD protecting several circuits.

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