Best electric blankets: six compared, and why a quarter of the ones brought in for testing fail

Check the one you already own, before you read anything else

Oxfordshire fire and rescue and trading standards run free electric blanket testing, and their published finding is that almost a quarter of the blankets brought in last year failed and were deemed unfit to use. Most failures are down to age, and they try to retain any blanket over ten years old.

One in four. That is the number that should decide what you do next, and it applies to the blanket on your bed right now rather than to anything on this page.

What to look for yourself: scorch marks or discoloured patches, exposed or kinked element wires, fraying fabric, a damaged or worn flex, a controller that is cracked or smells hot, and damp patches or staining. Lay it flat and look at it in daylight. If anything on that list is present, it goes in the bin rather than back on the bed.

The age tell is easy. If your blanket carries the old round BEAB safety symbol, it is more than a decade old and it should be replaced. Fire services and the safety charity say the same thing.

And never buy one second hand. Electrical Safety First are explicit about this: you have no way of knowing how it has been stored, folded or treated, and the damage that causes fires is mostly invisible until it is not.

BEAB, UKCA and CE, and why they are not the same

This is the single most useful thing to understand before you buy. The BEAB mark means a third party independent of the manufacturer has tested the product against the relevant safety standard and certified it. A UKCA or CE mark on a household appliance is, in most cases, the manufacturer declaring that their own product conforms.

Both are legal. Only one involves somebody outside the company opening it up. On an appliance that heats itself underneath a sleeping person, we think that distinction is worth actively shopping for, and it is why the £65 Slumberdown scores as well as it does against blankets costing twice as much.

The standard itself, if you want to check a claim, is BS EN 60335-2-17, which is the particular requirements part covering blankets, pads and similar flexible heating appliances. Do not confuse it with the BS 7175, 7176 and 7177 series, which are about the flammability of the textile rather than the electrical safety of the appliance.

Underblanket or overblanket, and why it changes the safety picture

An underblanket goes under the bottom sheet and heats the bed. The intended use, and every manufacturer says this, is to warm the bed before you get in and then turn it down or off. Underblankets get compressed by your body weight, which is why bunching and rucking matter so much, and why a fitted skirt beats straps.

An overblanket or heated throw goes over you, usually on a sofa. Nothing compresses the element, it cannot ruck under a sheet, and you are not lying on top of it. It is the safer format and it is also the one that suits a living room rather than a bed. If you want to heat a double bed, buy an underblanket. A throw sized product will not do it, whatever the picture on the box implies.

Never use either one with a hot water bottle. That combination comes up on every fire service list, and the reason is that a leaking bottle puts water into a live electrical element.

Who should not use one

This list is genuinely important and it is usually buried in the small print, so here it is from a manufacturer care guide, in their own terms. An electric throw or blanket must not be used by or on an incapacitated or immobile person, someone who is diabetic or insensitive to heat, a paraplegic, quadriplegic or amputee person, someone with poor blood circulation, anyone with cuts, skin lesions, sores or damaged skin, anyone unable to understand the instructions or operate the controller, children under three, or any person unable to react to overheating.

The reason is low temperature contact burns. Skin does not need to touch anything hot to be damaged. Prolonged contact with something moderately warm will do it, and it happens to people who cannot feel the heat building or cannot move away from it. Diabetic neuropathy is the most common reason for reduced sensation in the feet, and the feet are exactly where a heated underblanket sits.

If you have a pacemaker or any implanted device, check with your clinic before using one rather than taking a view from a leaflet.

EMF, honestly

Some readers will want this addressed, and it deserves a straight answer rather than either scaremongering or a sneer.

A mains appliance running at 50 hertz produces two things. An electric field, which exists whenever the appliance is plugged in and live, even with the controller switched off. And a magnetic field, which exists only when current is actually flowing. Both are extremely low frequency and non ionising, meaning they do not break chemical bonds and they are not radioactivity. An electric blanket is unusual among appliances only because it sits a couple of centimetres from your body for hours.

The measured numbers vary enormously with design and age. Compiled published measurements give typical magnetic flux densities of roughly 0.5 to 1.2 microtesla with maxima up to around 30 microtesla very close to the element, against an international public exposure reference level of 200 microtesla. So magnetic fields sit below the guideline. Electric field measurements are less comfortable: figures up to around 7 kilovolts per metre on top of a blanket appear in older studies, against a reference level of 5 kilovolts per metre. Older blankets with a single loop element are much worse than modern ones, which use a counter wound element that cancels a lot of the field by design.

On the health evidence: in 2002 the International Agency for Research on Cancer classified extremely low frequency magnetic fields as Group 2B, possibly carcinogenic. Electric fields were not classified at all. Group 2B means limited evidence in humans and less than sufficient evidence in animals, and it is the weakest category the agency uses for anything it classifies. It also classifies hazard rather than risk, meaning could this cause cancer under some conditions, not how likely is it to hurt you at the dose you actually get. Group 2B is a famously mixed bag that has included pickled vegetables and, for a time, coffee.

The practical upshot is boring and it is the same advice the manufacturers already give for a different reason. Heat the bed, then switch it off and unplug it before you get in. You get a warm bed, no field at all while you sleep, and the lowest running cost. If it matters to you, that costs you nothing.

Running cost, done properly

This is why sales spiked, so the arithmetic is worth doing rather than repeating a slogan. At 26p per kilowatt hour a 150 watt underblanket at full rated draw costs 3.9p an hour. But rated draw is not real draw, because the thermostat cycles. Independent testing measured actual consumption at 36 watts on one premium underblanket and 18 watts on a budget throw, which is under a penny an hour and under half a penny respectively.

A thirty minute preheat therefore costs somewhere around one to two pence. Compare that with running central heating for a whole house to keep one person warm in bed and the case makes itself.

One caution on the marketing. Several brands advertise approximately one penny per night. That figure refers to a short preheat, not to running it all night, and we would not repeat it without saying so.

Washing and storage, which is where blankets get damaged

Almost all of these are machine washable now, but the details matter. Detach the controller first and never let it get wet. Use the temperature on the label, usually 30 or 40 degrees, and a gentle cycle. Most cannot be tumble dried, and the ones that can are worth seeking out precisely because a blanket that takes three days to line dry in January is a blanket that stops being washed. Never iron one, and never dry clean one, because solvents attack the insulation on the element.

Never switch it on to dry it out. That is on every warning list for a reason.

For storage, roll it or lay it flat. Do not fold it, because a fold is a stress point in the element wire and repeated folding along the same line is exactly how a blanket develops the invisible damage that shows up as a fault years later. Do not put anything heavy on top of it in a cupboard.