If your RCD keeps tripping and will not stay on, it can be worrying and inconvenient, especially if it is knocking out lights, sockets or your fridge. The good news is that an RCD tripping is usually a sign it is doing its job and protecting you from electric shock, but it does mean something needs attention.
What an RCD actually does
An RCD (residual current device) constantly compares the electricity flowing out on the live conductor with the electricity coming back on the neutral. If it spots an imbalance, it cuts the power very quickly.
That imbalance usually means some current is leaking to earth, perhaps through a damaged cable, damp fitting or even through a person. By cutting off the supply in a fraction of a second, the RCD reduces the risk of serious electric shock and some types of electrical fire.
Typical reasons your RCD keeps tripping
There are several common reasons an RCD will not stay on. Understanding them can help you work out what to check first at home.
Faulty appliance: A failing kettle, toaster, washing machine or other plug-in item can leak current to earth and trip the RCD whenever it is used or even just plugged in.
Moisture ingress: Steam in bathrooms, leaks under sinks, water in outdoor sockets or garden equipment can get into fittings and wiring.
Outdoor circuits: Sockets in sheds, garages and gardens suffer from weather, damaged leads and pests chewing cables.
Nuisance tripping: Some circuits run close to the RCD rating, so small extra leaks from several devices add up and cause occasional trips.
Wiring issues: Problems such as insulation breakdown, damaged cables or borrowed neutrals can make an RCD very sensitive.
In some cases the RCD itself can also become faulty with age or after repeated heavy fault currents. A faulty RCD may trip at random, not reset properly, or refuse to trip when tested.
Staying safe before you touch anything
Before you start trying to reset or test, stand back for a moment and check for any obvious danger. If you notice a burning smell, hissing, buzzing, scorch marks or very hot plastic around the consumer unit or any socket, do not keep trying to reset the RCD.
In that situation, switch the main switch off if it is safe to reach, avoid using any affected sockets or appliances, and contact a qualified electrician urgently. Repeatedly forcing an RCD back on against a serious fault can make damage worse.
A safe step by step process to track down the fault
If there are no signs of overheating or burning, you can carry out some simple checks. Work calmly, use a torch if needed, and never remove covers from your consumer unit yourself.
Step 1: Unplug appliances on the affected circuits
Start by unplugging as many appliances as you can, not just switching them off at the front. Pay particular attention to:
Kitchen appliances such as kettles, toasters, dishwashers and washing machines, portable heaters, outdoor tools and extension leads, and anything in damp areas such as bathrooms or outside.
Step 2: Try resetting the RCD
Go to your consumer unit and identify the tripped RCD. Push the lever fully down if needed, then firmly back up to reset. If it stays on with everything unplugged, that suggests the fault is likely with an appliance rather than the fixed wiring.
Now plug your appliances back in one at a time, leaving a short gap between each. If the RCD trips when a particular item is plugged in or switched on, stop using that appliance and have it inspected or replaced.
Step 3: Testing circuits one by one
If the RCD trips immediately even with everything unplugged, or controls several circuits, try turning all the individual circuit breakers under that RCD off. Then reset the RCD with all those breakers off.
If the RCD now stays on, turn the circuit breakers back on one at a time. When the RCD trips as you switch a particular circuit on, you have narrowed the fault down to that area, such as downstairs sockets or upstairs lights.
At this point it is usually best to stop and call an electrician, as the issue is likely with the fixed wiring or a permanently connected appliance on that circuit.
Common wiring and installation issues
Not every RCD trip is caused by a simple appliance fault. Over time, insulation on cables can deteriorate, screws can loosen and DIY alterations can introduce wiring errors.
Problems such as borrowed neutrals between circuits, damaged cables under floors, or incorrectly connected outdoor sockets can cause confusing, intermittent trips. These usually need test equipment to track down safely.
In homes with older consumer units, the RCD may also be overloaded with a lot of circuits on one device, which can contribute to nuisance tripping even if each individual circuit is within limits.
When it is urgent to call an electrician
There are times when waiting is not a good idea. Contact an electrician promptly if any of the following apply:
No power to critical circuits, such as fridges, freezers, medical equipment or heating controls, and the RCD will not reset.
Signs of overheating, burning smell, discolouration or cracking around the consumer unit, sockets or switches.
RCD trips repeatedly overnight or when no one is using appliances, which can point to wiring or moisture issues.
You feel unsure, unsafe or out of your depth at any point in your own checks.
Do not ignore frequent RCD trips. They are a symptom of a fault somewhere, and dealing with that fault early usually means a safer home and less disruption in the long run.
What an electrician will typically check
A good electrician will not just keep resetting the RCD. They will carry out systematic fault finding to locate the cause and confirm your installation is safe.
This usually involves dead testing with the power off to check continuity and insulation resistance of the circuits, and live testing to measure earth fault loop impedance and confirm disconnection times. They will also test RCD trip times and currents to make sure the devices are working within the correct limits.
Depending on the results, they may recommend repairs to damaged wiring or fittings, rearranging circuits, or upgrading the consumer unit to a modern board with individual RCBO protection to reduce nuisance tripping.
Next steps and how DC Electrix Ltd can help
If your RCD keeps tripping and you are not getting anywhere with basic checks, it is time for a professional inspection. DC Electrix Ltd can carry out targeted fault finding and full electrical testing (EICR) to identify the cause and advise on the best fix.
Where your consumer unit is old or no longer suitable, we can also quote for a modern consumer unit replacement with improved protection and clearer circuit layout. To book a fault find or inspection, or to discuss electrical testing and upgrades, call DC Electrix Ltd on 07415049613 and we will be happy to help.
For more information on upgrading your board, visit our consumer unit replacement page, and to learn about periodic safety checks see our electrical testing and EICR information. Taking action now will help keep your home safe, reduce nuisance trips and give you greater peace of mind.
