Is It Safe to Leave a Charger Plugged In? What the Guidance Says

This question gets confident answers in both directions online. This guide does something narrower: it sets out what fire-safety and energy bodies have actually published, separates the three situations people mean when they ask, and says plainly where the guidance stops. We did not test any charger.

Three situations, three answers

Where the real incidents are

None of these tells you how likely a problem is. We found no published figure for fires started by idle chargers, and we are not going to supply one.

The case for unplugging anyway

• It is the standing fire-safety advice. The US Fire Administration’s guidance on appliances is to unplug small ones when you are not using them.
• You cannot inspect the inside of a charger. A fault in the circuitry is not something an owner can check for in advance.
• Standby power. Lawrence Berkeley National Laboratory, a Department of Energy laboratory, lists empty battery chargers among the things worth unplugging, and a federal office-energy checklist names phone chargers. The saving from one charger is small; the laboratory’s point is that standby loads add up across a home.

Against that, the laboratory also notes a practical caution: do not keep plugging and unplugging something with a worn cord. A power strip with a switch is another way to cut the power; that suggestion is ours.

If you leave chargers plugged in

Many people will, particularly for chargers behind furniture. These points come from Electrical Safety First and the fire agencies.

• Use the charger that came with the device, or one from the device maker or another reputable brand.
• Keep chargers uncovered and ventilated, away from heat, direct sunlight and liquids.
• Check them from time to time for burn marks, a buzzing or crackling sound, or a body that is too hot to touch. Check the outlet as well.
• Unplug at once if you notice a smell, sparking, smoke, swelling, cracks or other damage, and do not try to repair it.
• Plug straight into the wall where you can, and do not overload a outlet or strip.
• Have working smoke alarms.

Bigger batteries are a separate matter

Everything above is about phone-sized chargers. For e-bikes, scooters and other large batteries, the CPSC’s advice is firmer: be present while they charge, do not charge them while you are asleep, use only the manufacturer’s charger, and disconnect when charging is complete. Our summary of e-bike and scooter battery recalls covers this, and the lithium battery safety guide sets out charging, storage and disposal for every kind of battery product.

Which chargers are safe to leave plugged in?

We looked for an official list and did not find one. No agency we read certifies a charger as safe to leave in the wall indefinitely, and a certification mark tells you a product was tested against a safety standard, not that it can be forgotten about. What you can do is reduce the odds: buy from a reputable seller, look for a recognized testing laboratory’s mark on the charger itself, and check the model against recall notices. Our guide to checking for recalls shows how, and how to spot a failing battery covers the device on the other end of the cable.

How we researched this

We read the US Fire Administration’s and National Fire Protection Association’s published safety advice, the UK charity Electrical Safety First’s guidance on USB chargers, CPSC warnings and news releases about chargers, and Lawrence Berkeley National Laboratory’s pages on standby power. Electrical Safety First writes for UK homes, where plugs and outlets differ, so we have used only its general advice. We did not test any charger, and we found no statistics on idle chargers specifically.