Are electric blankets safe, and how much do they cost to run?

Electric blankets are simultaneously one of the cheapest ways to be warm in a cold house and one of the more common causes of accidental domestic fire. Both facts are true because the appliance is a low-power heating element woven through a soft item that gets folded, sat on, stored in a loft and kept for decades. The wiring inside is what fails, and it fails at creases, at the connector, and with age — none of which is visible unless you look for it. The safety of an electric blanket is almost entirely a question of its condition, and its condition is almost entirely a question of how it was folded and how old it is.

Safety

What you'll need

• A bright light, for the inspection
• The manufacturer's instructions for your specific blanket
• A tube or a flat storage space, for the summer (optional)

Step by step

1. Find out how old it is, and apply the ten-year rule.Ten years is the widely recommended maximum life for an electric blanket, and fire services routinely recommend replacing at that point whatever it looks like. The insulation on the internal wiring degrades with every heat cycle in a way you cannot see. If you do not know the age, that is itself a reason to replace it.
2. Inspect the flex and the plug.Fraying, cracked or hardened insulation, exposed conductors, kinks where it leaves the plug, and a plug that is warm, discoloured or scorched round the pins. Any of those and the blanket goes out of use now, not at the end of the winter.
3. Inspect the controller and its connector.It should clip in firmly with no play, and neither half should show browning, melting or bent pins. A connector that has to be wiggled to work is arcing inside, and arcing inside a bed is exactly the failure to prevent.
4. Feel for the wiring inside the blanket.Lay it flat and run flat palms over the whole area, or hold it up to a bright light. You are feeling for wires that have kinked, bunched together, crossed, or wandered away from their even spacing. Bunched or crossed wires make a hot spot, and hot spots are how blankets scorch.
5. Look at the fabric for scorch marks and hard patches.Brown or yellow discolouration, an area that feels crisp or hard, a smell of burning when it is warm, or any sign that the blanket has been wet at some point. All are end-of-life indicators and none of them improves.
6. Check the safety marking and the fitting.It should carry proper safety marking and, on an underblanket, tie tapes or corner elastics that hold it flat and taut on the mattress. A blanket that slides and rucks under a sleeper folds its own wires every night.
7. Use it the way it was designed to be used.An underblanket goes under the bottom sheet, flat and taut, and is generally for warming the bed before you get in rather than for sleeping on. An overblanket goes over you. Never swap the two. Follow the manufacturer's instruction on all-night use — most underblankets must be switched off before you sleep, and only blankets specifically stated as suitable may stay on.
8. Never combine it with anything else that heats or holds water.No hot water bottle in the same bed as a switched-on electric blanket. A leaking bottle onto live heating wires is the classic serious accident. Nothing else on top of it either — no extra layers of duvet piled on an overblanket, which traps heat against the element.
9. Cost it honestly, using its own wattage.Most electric blankets draw somewhere between 50 and 150 watts, and it is on the rating label. Take the watts, divide by 1,000, multiply by your own unit rate, and multiply by the hours. Even at the top of that range and at a full evening's use it is a very small number, and it is a fraction of heating the room to the same comfort.
10. Store it flat or loosely rolled, never folded tight.A hard crease is exactly where a heating conductor breaks. Roll it around a tube, or lay it flat under the mattress or on top of a spare bed, with nothing stacked on it. Keep it somewhere dry — not a loft, not a garage, not a damp cupboard. Detach the controller rather than leaving it hanging by its connector.
11. Have it tested, or replace it, if you are in any doubt.Some fire and rescue services and local authorities run free electric blanket testing sessions in autumn. If one is available near you it is the best possible answer to an uncertain blanket. If not, and there is any doubt at all, replace it — new blankets are inexpensive relative to the risk.

Tips

• Do the inspection when you get it out in autumn, not on the first cold night when you want to use it. That is when a fault turns into a decision to risk it.
• A heated throw is often the better purchase for evenings on the sofa — same principle, lower power, no bed involved, and it can be washed more easily on most models.
• Photograph the rating label and note the purchase year somewhere. The ten-year rule is only usable if you know when the clock started.
• Warm the bed for half an hour before you get in and switch it off, unless the manufacturer explicitly permits all-night use. It is warmer, cheaper and safer.
• Check the washing instructions before washing. Many blankets can be washed, many cannot, and getting an unwashable one wet ends it permanently.

Common mistakes

• Keeping a blanket well past ten years because it still works — The failure is in insulation that degrades invisibly with every heat cycle. Working today is not evidence about tomorrow, and old blankets are heavily over-represented in electric blanket fires.
• Folding it tightly for summer storage — A sharp crease is where the heating conductor breaks or where the insulation is worn through. Roll it or lay it flat.
• Using a hot water bottle in the same bed — A leak onto live heating elements is one of the most serious accidents an electric blanket can be involved in. Never both.
• Switching it on while still folded to warm it faster — The heat cannot escape from between the folds and the fabric can scorch or ignite. It must be flat before it is switched on.

If it doesn't work

Questions people ask