A trip switch that keeps cutting the power is not being difficult. It is doing the job it was designed for: detecting a fault and disconnecting the supply before anyone is hurt. The useful question is not how to stop it tripping, but what is causing it to trip. A calm check can narrow that down without touching anything you should leave alone.
What the switch does
A consumer unit holds several protective devices. A miniature circuit breaker, often called an MCB, protects a circuit from overload and short circuits. A residual current device, or RCD, compares the current going out with the current coming back and trips when the difference suggests a leak to earth. Many modern units combine both in one device, sometimes called an RCBO. The label beside each switch usually tells you which circuit it protects, such as sockets, lights, cooker or shower.
What to do first
Stay calm and work in daylight if you can. Do not touch the consumer unit with wet hands, and do not remove its cover. The switches you are meant to use are the ones on the front.
- Switch off and unplug the appliances on the circuit that has tripped, especially anything with water nearby.
- Reset the switch once, firmly, and see whether the power stays on.
- If it holds, plug the appliances back in one at a time, testing after each one.
- If it trips again during that process, leave the last appliance unplugged and out of use.
- If it trips with nothing plugged in, leave the switch off and call an electrician.
Common causes
Water is a frequent culprit. A kettle that has boiled over, a washing machine with a leak, or a socket near a window can let moisture reach the electrics. Damaged cables, worn plugs and appliances with a fault inside are others. So is a circuit that is asked to carry more than it should, though that usually trips an MCB rather than an RCD. Older wiring and outdoor equipment can also be involved, particularly after heavy rain.
Think about what changed just before the power went off. A new appliance, a bulb replacement, a drill through a cable or a leak under the sink are all useful clues to pass on. If the same switch trips whenever a particular appliance runs, stop using that appliance until it has been checked.
What not to do
Never work on a circuit that is live, and never open a consumer unit or a socket to investigate. Do not tape a switch in the on position, fit a larger fuse or breaker, or keep resetting a device that trips immediately. Each of those removes the protection that is there to prevent fire and shock. If the power is off to a fridge or freezer, keep the door closed and the food will stay cold for a while.
Getting help
If you cannot find the cause, or the switch will not stay on with everything unplugged, book an electrician. Tell them which switch tripped, what you had plugged in and what you have already tried. That saves time on the visit and helps them go straight to the likely fault.
