Why your electrics keep tripping

The devices in your consumer unit trip to protect you and your house. When one keeps tripping, it is doing its job, and the fault is somewhere else. This guide explains what the different kinds of trip mean and what you can safely do about them. It deliberately stops short of anything that involves the consumer unit itself, because that is our job and not yours.

Two kinds of trip

Most modern consumer units have two kinds of protective device. Circuit breakers, one per circuit, trip on overload or a short circuit. Residual current devices, which usually protect several circuits at once, trip on a leak of current to earth, which is the kind of fault that gives people electric shocks. Some units have combined devices that do both.

If a single small switch has gone down, that is a breaker and the problem is on that circuit. If a larger switch has gone down and several circuits are dead, that is the RCD, and the fault is on one of the circuits it protects.

Is it something you plugged in?

The commonest cause of a tripping circuit is an appliance. Older fridges and freezers can do the same.

Unplug everything on the affected circuit, or the appliance you suspect if the trip coincides with it running. You may reset the device once. If it holds, plug things back in one at a time over the next day and see which brings it down. If it trips again immediately with everything unplugged, or you cannot find the culprit after a couple of tries, stop there.

What is safe and what is not

Unplugging appliances and resetting a tripped device once are safe. Repeatedly resetting a device that keeps tripping is not; you are putting a fault under load again and again, and if the fault is heat or a damaged cable, that is how fires start. Do not remove the cover of the consumer unit, do not touch anything inside it, and do not replace a breaker with a larger one because the old one keeps tripping.

Do not open sockets, switches or light fittings to look. If a socket is discoloured, warm, or smells of burning, do not use it and read our guide on a burning smell from a socket. If there is any water involved, from a leak or flooding, leave the consumer unit alone entirely and call us.

Causes we find that are not appliances

When the appliances are ruled out, the usual causes are moisture in an outside socket, a garden light or a shed supply; a damaged cable where a picture hook, screw or rodent has gone through it; deteriorated wiring in a house that has not been rewired since the seventies; a light fitting that has been fitted badly; or a fault in the consumer unit itself. In the older houses around Prestwich and Worsley we also see circuits that have been extended and extended again until the protection no longer matches the load.

An RCD that trips at random, especially at night or in wet weather, is very often moisture. A breaker that trips when the shower or the oven is on is usually an overloaded or failing circuit. Both need testing with proper instruments to find, and neither is a guess we can make down the phone.

What we do

We isolate the circuits one at a time and test each for insulation resistance and earth leakage, which tells us which circuit has the fault and roughly where on it. Then we trace it. Sometimes that is a junction box in the loft; sometimes it is a cable buried in a wall.

If the consumer unit is an old rewireable type with no RCD protection, we will tell you, and explain what a replacement involves. It is not something we push, but it is the single biggest safety improvement available in an older house.

If your electrics have gone off completely and will not reset, if a device is hot to touch, or if you have a burning smell, use the emergency electrician page or call the emergency line on 07893 933403.