Tripping circuits and electrical faults in Epping Forest and West Essex

Which switch on the board has gone, and what does it protect?

Modern consumer units hold three kinds of device, and knowing which one has moved tells you a lot. A circuit breaker guards one circuit against overload and short circuit, so if the one marked kitchen sockets drops, the problem lies on that circuit. An RCD watches for current leaking to earth, often through damp or a faulty appliance, and it usually covers several circuits at once, so everything on its half of the board goes dark together. An RCBO does both jobs for a single circuit. Older boards may have rewirable or cartridge fuses instead, where a wire inside the carrier melts and has to be replaced with wire of the right rating.

Before you reset anything, look at the labels. If they are blank or out of date, note which rooms lost power, because that is the first thing an electrician will ask.

Why does the board trip when I use one particular thing?

A fault inside an appliance is the most common reason for an RCD to drop. Washing machines, tumble dryers, dishwashers, kettles, irons and immersion heaters all contain heating elements, and when an element cracks or its insulation breaks down, a small current leaks to earth and the RCD does its job. Older fridges and freezers, electric showers and outdoor pressure washers do the same.

Unplug the suspect, reset the switch and see whether it holds. If it does, keep the appliance out of use and have it repaired or replaced; an electrician can confirm that the appliance rather than the wiring is to blame. If the board trips with everything unplugged, the fault is in the fixed wiring or in an accessory such as a socket or a light fitting, and that is where an electrician is needed.

What if nothing obvious is plugged in?

Tripping that seems random is often moisture. Rain getting into an outside light, a garden socket or a shed, condensation in a bathroom fan, a leak from a roof or a pipe tracking along a cable, or a light fitting in a damp porch can all leak enough current to trip an RCD, sometimes only after heavy rain or when the heating comes on. Rodents chewing cable in a loft, a nail through a cable from a recent shelf, and old cable whose insulation has gone brittle are other causes. The pattern matters, so note the weather, the time of day and anything that happened in the house just before.

Which faults are serious enough to stop everything?

Some signs mean switching off at the main switch and leaving the circuit alone until it has been looked at:

• a hot or discoloured socket, switch or plug
• a smell of burning or of fish from a fitting with no obvious source
• crackling or buzzing from a socket, a switch or the board
• a breaker that trips the instant it is reset, every time
• a tingle or shock from a tap, an appliance or a metal fitting

If there is smoke or flame, get everyone out and ring 999, and never put water on anything electrical. A shock from a tap or a pipe points to an earthing problem, which is a danger to the whole house rather than to one circuit.

My whole street is dark. Is that a fault in my house?

No. If neighbours have lost power too, or the lights along the road are out, it is a supply problem and the number to ring is 105, which connects you free of charge to the network operator for the area. Ring 105 as well if you see a damaged pole, a fallen overhead line or a cable showing in the ground. The incoming cable, the main fuse and the meter belong to the network operator and your supplier, not to you, and an electrician cannot work on them.

What does fault finding involve?

An electrician starts by asking what you have noticed, then tests rather than guesses. With the circuit isolated, they measure insulation resistance to find where current is leaking, check earth continuity, and often split the circuit into sections to narrow a fault down to one cable run or one accessory. Faults hide in junction boxes under floors, in lofts and behind kitchen units, so it can take time and can mean lifting a board or two. Once found, the repair may be as small as a new socket front or as large as a new cable run, and the electrician should explain which before going ahead.

Does a repair need to be notified to building control?

Replacing a damaged socket, switch, light fitting or short length of cable like for like is not notifiable under Part P of the Building Regulations in England. Adding a new circuit, replacing the consumer unit or doing work in the zones around a bath or shower is notifiable, and must either be carried out by an electrician registered with a government-authorised competent person scheme or be notified to the council's building control before it starts. If fault finding turns into something bigger, ask the electrician how the work will be certified; the rules are in Approved Document P.

What helps the electrician before they visit?

• which circuits or rooms are affected, and which device on the board has tripped
• whether it trips at once, after a few minutes or only now and then
• anything that sets it off, such as rain, a shower or one appliance
• how old the board looks, with a photo if you can take one without touching anything
• whether you own or rent, since a landlord may need to be involved
• your postcode and a number to ring

With your consent, one local electrician who covers your postcode, if there is one, receives the enquiry. If nobody does, we tell you and your details go no further.