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How to reset a tripped RCD
A residual current device (RCD) cuts the power when it senses a fault that could give you an electric shock. A trip is annoying, but it is the device doing its job.
What the switches do
Most modern UK homes have a consumer unit (fuse box) with a main switch, one or more RCDs, and smaller switches called MCBs (miniature circuit breakers) for each circuit. An RCD trips when current leaks to earth, for example through a faulty appliance or damaged cable. An MCB trips when a circuit is overloaded or has a short circuit.
Step by step: reset it
- Stay calm and stay dry. Do not touch the unit with wet hands. Use a torch if needed.
- Look at the consumer unit. Switches that have flipped down (or to the middle position) have tripped.
- Unplug appliances in the affected area, especially those that were running (kettle, washing machine, dishwasher, hairdryer, fridge).
- Push the tripped switch back up. If it is an RCD, the MCBs below it may also be off; switch them on one at a time.
- Plug appliances back in one by one. If the RCD trips again when you plug one in, you have found the faulty item. Leave it unplugged.
If it trips again with everything unplugged
Switch off all the individual circuit switches, reset the RCD, then switch circuits on one at a time. If one circuit makes it trip, that circuit has a fault. Leave that one off and call a registered electrician. Do not hold the switch up, tape it or bypass it. Possible causes are damp in outdoor lights or sockets, a damaged cable (perhaps from a drill; see hanging shelves safely), or a fault with an immersion heater or cooker.
Nuisance tripping
RCDs can trip because of storms and damp, or several appliances each leaking a tiny amount of current. If an RCD trips regularly without a clear cause, it should still be investigated by a qualified electrician, who can test the circuits and, if appropriate, split the load across additional RCDs.
Test your RCD
RCDs have a test button, marked T or Test. Check your consumer unit's label or manual for how often to test it, and press the button to see the switch flip off. If it does not, the device is not protecting you, so call an electrician. Press the button, then switch it back on. Check any items with a clock or timer afterwards.
A word on old fuse boxes
If your home has an old fuse box with ceramic rewirable fuses and no RCD, the safety protection is much lower. Ask an electrician to inspect it and consider an upgrade. GOV.UK lists installing a new or replacement consumer unit as work that must be notified to building control; see electrical DIY rules.
Never
- Open the consumer unit cover and touch the inside.
- Replace a fuse or breaker with a larger one.
- Carry on using an appliance you know trips the RCD.
Common culprits
The appliances that most often cause an RCD to trip are older kettles, toasters, hair dryers, washing machines and dishwashers with a damaged element or seal, immersion heaters, and electric garden tools. Water is the usual trigger: a leaking pipe near a socket, a wet outside light or an appliance with a fault. Look for scorch marks, buzzing sockets, a burning smell or a socket that is hot to touch. These are warning signs to stop using that circuit and call an electrician. Keep a torch near the consumer unit so you can reset it safely at night.
Frequently asked questions
Is it safe to reset an RCD myself?
Yes, pressing the switch on the front is safe if your hands are dry and the cover is closed. Do not remove covers.
How often should I test my RCD?
Check the label on your consumer unit or the manufacturer's instructions for how often to press the test button.
Why does my RCD trip when it rains?
Damp in outside sockets, lights or cables is a common cause. Have an electrician check outdoor wiring.