Use this guide when some or all of your lights or sockets go off but the street still has power. Have a torch ready and know where your consumer unit (fuse box) is before you start.
Step by step
Check it is not a power cut
Look outside to see whether neighbours and street lights still have power. If the whole area is off, call 105, the free national power cut number, rather than touching your fuse box. If only your home or part of it is off, a switch has probably tripped.
Find the tripped switch
Open the consumer unit cover and look for a switch pointing down or in the middle position. Small switches are circuit breakers (MCBs) for single circuits; larger ones labelled RCD or with a T test button protect a group of circuits. Note which one has tripped.
Unplug and switch off
Switch off and unplug appliances on the affected circuits, especially kettles, toasters, washing machines, heaters and anything outdoors. If a light fitting failed with a bang, switch that light off at the wall. This stops the fault tripping the switch again straight away.
Reset the switch
With dry hands, push the tripped switch firmly all the way to off, then back up to on. If it stays on, power is restored. If it trips again immediately with everything unplugged, leave it off and call a qualified electrician.
Find the faulty appliance
Plug appliances back in and switch them on one at a time, waiting a moment between each. When the switch trips again, the last item is the likely culprit. Stop using it, label it and get it repaired or replaced.
Know when to stop
Call a registered electrician if the switch keeps tripping for no clear reason, you see scorch marks, smell burning or hear buzzing, or water has got into sockets or fittings. Never remove the consumer unit cover or replace parts yourself. If there is smoke or fire, get out and call 999.
Ready-to-use checklist
- Torch kept near the consumer unit
- Dry hands and dry floor before touching switches
- Appliances on the affected circuit unplugged
- Switch pushed fully off before resetting
- Appliances reconnected one at a time
- Faulty item labelled and taken out of use
- Circuits labelled for next time
Practical tips
- Label each switch in the consumer unit with the rooms it serves, so next time you know exactly what has gone off.
- Press the RCD test button every few months as recommended on the label: it should trip, and you then reset it.
- Outdoor appliances and extension leads left in the rain are a common cause of RCD trips in autumn and winter.
Common problems
The RCD trips at random, often at night or when it rains.
This often points to damp getting into an outdoor socket, light or cable, or to an appliance such as a fridge or immersion heater developing a fault. Note when it happens and what was running, then get a registered electrician to test the circuits.
The switch will not stay up even with everything unplugged.
The fault is likely in the fixed wiring or a light fitting rather than an appliance. Leave it off, keep people away from the affected circuit and call a qualified electrician. If you rent, report it to your landlord straight away.
My home has an old fuse box with wire fuses instead of switches.
Do not attempt to rewire fuses yourself. Switch off at the main switch and call an electrician, and ask about upgrading to a modern consumer unit with RCD protection.
This guide gives general information, not personal legal, financial or medical advice. Rules and prices change, so check the current position with the official service before acting.
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