My appliance has no power — is it the appliance or the socket?

The reason this question is worth answering carefully is that it splits into two completely different situations, one of which is a household job and one of which is not. The test that separates them takes about a minute and needs nothing but a lamp. Everything before that test is guesswork, and quite a lot of money is spent every year on engineer call-outs for appliances that turned out to be plugged into a dead socket, and on electricians for sockets that turned out to be fine.

Safety

What you'll need

• A lamp or phone charger you know works
• A spare fuse of the correct rating for the appliance
• A torch, for reading a rating plate or finding a reset button (optional)

Step by step

1. Stop first if any warning sign is present.Burning smell, scorch marks, a warm or discoloured plug or socket, buzzing, or a shock. Switch that circuit off at the consumer unit, stop using the socket, and call an electrician. None of the steps below apply and continuing is the wrong decision.
2. Check whether anything else on that circuit works.If several sockets or the whole area are dead, look at the consumer unit — a breaker or an RCD has operated, and that is a different problem with its own procedure. If only this one appliance is dead, carry on.
3. Put a known-good lamp in the same socket.This is the whole test. A lamp or a phone charger you have just seen working elsewhere. If it lights, the socket delivers power and the fault is downstream of it. If it does not, the socket or the circuit is the problem and you stop here.
4. Check the socket switch and any switched spur.Obvious, and frequently the answer. Many kitchen appliances are fed from a switched fused spur above the worktop as well as a socket behind the machine, and either can be off. The spur also has its own fuse, which is a separate thing from the plug fuse.
5. Change the plug fuse for one of the same rating.3A for appliances up to about 700W, 13A above that, unless the appliance's own instructions state otherwise — and they override any general rule. Never fit a higher rating. If a new correct-rating fuse blows immediately, the appliance has a fault and the diagnosis ends there.
6. Run the flex through your fingers along its whole length.Cuts, crushing where furniture has stood on it, hardened or cracked insulation, kinks close to the plug where it flexes most, and any looseness where it enters the appliance body. A damaged flex is replaced, not taped. On a moulded plug the whole lead is replaced.
7. Check the appliance's own interlocks and controls.A door catch that is not engaging on a washing machine or dishwasher, a lid switch, a child lock, a delay start set by accident, a control lock, or a program left mid-cycle. Machines are routinely declared dead when a door is not quite shut.
8. Look for a thermal cut-out reset button.Heaters, tumble dryers, waste disposal units, some vacuum cleaners and some kitchen machines have a manual reset, often a small button on the base or the rear. It trips on overheating and the machine stays completely dead until it is pressed back in — after the machine has cooled.
9. Check the supplies the appliance needs, not just electricity.A washing machine or dishwasher with the water supply turned off often shows nothing at all rather than an error. Check the isolating valve behind the machine, and check the drain hose is not kinked.
10. Try the appliance in a different socket, if it is safely portable.For a portable appliance only, and never with an extension lead. If it works in another socket, the fault is at the first socket. If it is dead in both, it is the appliance.
11. Decide which of the two answers you have reached.Fault proven inside the appliance: that is now a repair-or-replace decision, with the model number and the fault in hand. Fault proven in the socket or circuit: that is an electrician's job and nobody else's, and the socket should not be used in the meantime.

Tips

• Keep a couple of 3A and 13A fuses in the house. Discovering there are none at the moment something stops working is the classic annoyance.
• A lamp with an incandescent or a cheap LED bulb makes the better test light than a phone charger, because you can see it work from across the room.
• If the same appliance blows fuses repeatedly, that is a fault and not bad luck. Replacing the fuse over and over is not a fix and is not safe.
• Note what you found before calling anyone. An engineer or electrician arriving to a clear description of what was tested spends less of your money working it out again.

Common mistakes

• Fitting a higher-rated fuse because the correct one keeps blowing — The fuse protects the flex, not the appliance. A higher rating means the cable can overheat before the fuse operates, which is a fire risk. A blowing fuse is telling you something.
• Booking an engineer before testing the socket — A one-minute lamp test would have found a dead socket or a switched-off spur. Call-out charges are commonly £70 to £120 and are usually payable whether or not there was a fault.
• Testing an appliance through an extension lead — It adds a second plug, a second fuse and a length of flex to the list of things that could be at fault, and for a high-power appliance it introduces a genuine hazard.

If it doesn't work

Questions people ask