The short answer
To reset a tripped MCB (miniature circuit breaker) or RCD (residual current device), first switch off or unplug everything on that circuit, then push the tripped switch back up to the ON position (or press the RCD test button and toggle the switch back). If it holds, switch appliances back on one at a time to find the one that caused the trip. If it trips again immediately — or if the RCD trips every time you try — do not keep resetting: there is a fault that needs a registered electrician to investigate. Repeated tripping is the protective device doing its job; it is not a malfunction to override.
A tripped switch in a consumer unit is usually straightforward to reset, but the steps matter. Resetting without investigating can mask a genuine electrical fault. Here is how to do it safely.
Resetting a trip
- What caused itoverload, short circuit, or earth leakage (RCD)
- First stepswitch off / unplug everything on that circuit
- Resetpush the tripped switch up to ON
- If it stays offthere is a fault — call an electrician
- If it keeps trippingdo not keep resetting; get it investigated
Understanding what has tripped
Modern consumer units contain different types of protective device, and knowing which has tripped helps you understand what happened:
- MCB (miniature circuit breaker): a small rocker or toggle switch, one per circuit. It trips on overload (too many appliances drawing too much current) or short circuit (a direct fault in the wiring or an appliance). It protects the circuit's wiring from overheating. MCBs are usually labelled by circuit: 'Lights downstairs', 'Ring main', 'Cooker', and so on.
- RCD (residual current device): a wider switch, often covering several circuits. It trips when it detects current leaking to earth — the condition associated with electric shock. An RCD trip is more significant than an MCB trip because earth leakage can indicate a wiring fault, a damaged appliance, or water ingress.
- RCBO: a single device per circuit that combines both MCB and RCD functions. If an RCBO trips, it may have detected either an overload/short or an earth-leakage fault.
On most boards, a tripped device will have moved to a mid-position or clearly switched to OFF. If the board is a dual-RCD type, check which of the two RCDs has tripped, because each covers a different group of circuits.
Steps to safely reset a tripped MCB
- Switch off or unplug all appliances and equipment on the affected circuit. This removes the load so that if the trip was caused by a faulty appliance, it does not immediately trip the board again on reset.
- Push the tripped MCB fully to the OFF position first (some boards require this step before the switch will go back to ON), then push it back up to ON.
- If it stays on, reconnect appliances one at a time. The one that causes the MCB to trip again is likely faulty. Stop using it and have it checked or replaced.
- If the MCB trips again immediately when you reset it, even with nothing plugged in, do not keep trying. A persistent trip with no load on the circuit points to a wiring fault. Call a registered electrician.
Steps to safely reset a tripped RCD
Resetting an RCD requires identifying what caused the earth-leakage trip, because unlike an MCB overload trip, an RCD trip indicates current was leaking in a way that could cause shock or fire:
- Switch off or unplug everything on the circuits covered by that RCD — usually half the board's circuits, or all socket circuits. Appliances should be switched off at the plug as well as unplugged where possible.
- Locate the tripped RCD (it will be in the mid or OFF position) and push it firmly back to ON.
- Reconnect appliances one at a time. If the RCD trips when you plug in or switch on a specific appliance, that appliance has an earth-leakage fault. Stop using it — it should not be used until it has been tested or replaced by a competent person.
- If the RCD trips again with nothing connected, or trips repeatedly with no obvious single cause, do not keep resetting. This pattern suggests a wiring fault — damaged insulation, moisture in cables or a socket, or a fault developing in a fixed installation. Call a registered electrician.
| Trip type | Likely cause | Action |
|---|---|---|
| MCB trips under load | Overloaded circuit — too many appliances | Reduce load; identify and remove the overloading appliance |
| MCB trips immediately (no load) | Short circuit or wiring fault | Do not reset; call an electrician |
| RCD trips — one appliance suspected | Faulty appliance with earth leakage | Unplug appliance; stop using until checked |
| RCD trips repeatedly (no single cause) | Wiring fault or moisture in installation | Do not keep resetting; call an electrician |
| RCD trips at night or randomly | Developing wiring fault or faulty appliance on standby | Investigate systematically; electrician if not resolved |
General guidance on trip types and appropriate responses. Sources: Electrical Safety First guidance.
When not to reset — and when to call an electrician
Resetting a trip is appropriate when there is a clear, identifiable cause (an overloaded circuit, a single faulty appliance) and the board holds on reset once that cause is removed. There are several situations where resetting is not the right response:
- The trip recurs immediately: a breaker or RCD that will not stay on even with circuits unloaded is indicating a fault in the wiring. Repeatedly resetting it increases risk and does not fix the fault.
- Burning smell or scorch marks: if there is any smell of burning, char marks, or heat around the consumer unit or a socket, do not reset anything. Switch off the main isolator if it is safe to do so and call an electrician immediately.
- The trip happens for no clear reason: if an RCD trips repeatedly and you cannot find a faulty appliance, the cause may be deteriorating wiring insulation, moisture ingress, or an intermittent fault that only a proper test will identify.
- After a flood or water damage: do not switch on or reset anything in an installation that has been flooded or wet. Have a registered electrician inspect it first.
A consumer unit's protective devices exist to disconnect the supply when a dangerous condition is detected. Overriding them by repeatedly resetting without investigating the cause defeats that protection.
Frequently asked questions
Why does my consumer unit keep tripping?
Repeated tripping usually means an overloaded circuit, a faulty appliance causing an earth-leakage trip, or a developing wiring fault. If the trip recurs after you remove all appliances, the cause is likely in the wiring rather than an appliance, and a registered electrician should investigate.
Can I reset an RCD myself?
Yes — resetting an RCD is safe if you first unplug everything on the affected circuits and then identify what caused the trip before reconnecting. If the RCD trips again immediately or keeps tripping without a clear cause, do not keep resetting: there is a fault that needs a registered electrician.
What if my RCD has no test button?
Every RCD should have a test button marked T (or 'Test'). If you cannot find one, or if pressing it does not trip the device, the RCD may be faulty or the device may not be a true RCD. An RCD that does not trip on its test button is not providing the protection it should — have a registered electrician check it.
Sources & further reading
- Electrical Safety First — your consumer unit and circuit breakers
- Electrical Safety First — what to do if your electricity trips
Figures on this page are typical UK ranges drawn from published sources and depend on your specific property and installation. They are guidance, not a quotation.