Emergency electrician and fault finding, Hull to Scarborough.

What to check before you ring

Look outside first. If the street lights and the neighbours' houses are dark as well, it's a power cut and the network operator deals with it. Ring 105, the free power cut number, or report it on their website.

If it's only your house, find the consumer unit and see which switch is down. A circuit breaker that has tripped once can be pushed back up. If it's an RCD, unplug everything on the circuits it covers, reset it, then plug things back in one at a time. When it trips again as one appliance goes back in, that appliance is the likely culprit.

Stop there and ring me if it trips again with nothing plugged in, or if a socket or the board smells of burning or looks scorched. Don't hold a switch up against a trip. An RCD that has been taped up or bridged out gives no protection at all.

Why an RCD keeps tripping

An RCD watches for current leaking to earth, which is what happens when a cable is damaged or someone touches a live part. It switches off quickly to cut the risk of a serious shock, so a trip means it has found something.

The usual causes are an appliance with a failing heating element, such as a kettle or a washing machine, or water getting into an outside light or socket. A screw through a cable in a wall will do it as well, and so will several small leaks that add up on one RCD.

Trips at night or in wet weather are usually rain or dew in an outdoor fitting, or an appliance on a timer switching on while you're asleep.

A circuit breaker that trips on its own is a different fault. It means too much current is flowing, from an overload or a short circuit.

On an older board with one RCD over half the house, a single fault takes every circuit on that side down. A consumer unit with RCBOs keeps each fault to its own circuit.

How I trace a fault

I start by asking what was switched on when it tripped, and whether it happens at a certain time of day or in certain weather.

Then I isolate the circuit and test it. An insulation resistance test shows whether current is leaking between the conductors or to earth, and splitting the circuit into sections narrows down where. I look over the connections at the sockets and the board as well, for anything loose or burnt.

Once I've found it, I make it safe and tell you what the repair involves and what it costs. If it can be done there and then, I do it once you've agreed the price. If it needs a part or a new length of cable, I come back to finish it.

When faults keep turning up on different circuits, it's time to test everything at once, and a condition report for the whole house does that.

Out-of-hours call-outs

Out of hours means evenings, weekends and bank holidays, and an attendance then costs more than a visit in working hours. It's charged even if you decide against the repair.

When you ring, tell me what's happened and I'll say whether it needs an out-of-hours visit or can wait for a working day. A circuit that has been switched off safely can often wait.

If a socket or switch smells of burning

Switch that circuit off at the consumer unit, or use the main switch if you're not sure which circuit it is, and don't use the socket again until it has been looked at. If there's smoke or flame, get everyone out and ring 999.

A burning smell usually means a connection that has worked loose and is overheating, or a plug and socket that have been overloaded. It won't put itself right, and heat at a loose terminal is how a lot of electrical fires begin.

Lights that flicker or dim

If every light in the house flickers and the neighbours' lights do too, the cause is on the supply side, and that's for the network operator.

Flicker on one light usually comes down to the lamp or its driver. Flicker across a whole circuit, or lights that dim when something big switches on, can mean a loose connection on that circuit, which needs finding before it overheats.

Faults I pass on

The main fuse and the cable into the house belong to the network operator, so faults there go to them.

Solar panel and battery faults go to the installer who fitted the system, or to a solar specialist.