How to spot a fake or unsafe charger before you plug it in

A phone charger is a small, sealed box with 230 volts going in one side and 5 to 20 volts coming out of the other. The only thing separating the two is a transformer and a few millimetres of air and insulation. In a well-made charger those millimetres are specified by a safety standard. In a counterfeit, they are the first thing to go, because distance and insulation cost money and nobody can see them.

That is why this guide does not promise a trick that proves a charger is safe. There isn't one. What there is instead is a set of checks — where you buy, what is printed on the box and the body, how the thing is built, and how it behaves once it is in use — that together catch the great majority of bad chargers.

The short answer

• Where you buy matters more than anything you can inspect. A big-brand charger at a small fraction of the brand's own price, from a marketplace seller, is the classic counterfeit.
• The failure rates are not marginal. In Electrical Safety First's 2015 study, 63 of 64 lookalike Apple chargers failed at least one safety test. In June 2026 Which? found that none of 15 chargers bought on online marketplaces could legally be sold in the UK.
• A CE mark is a claim, not a certificate. The European Commission says plainly that it "does not indicate that a product have been approved as safe by the EU or by another authority".
• Weight is no longer a reliable tell. Which? found chargers padded with modelling clay and a metal weight to feel substantial.
• Heat, buzzing, crackling or a burning smell mean unplug now, and do not use that charger again.

Why a bad charger is dangerous

A mains charger does two jobs. It converts voltage, and it isolates — keeps the mains side of the circuit electrically separate from the low-voltage side you touch through the cable and the phone. The second job is the one that keeps people alive, and it depends on physical separation inside the case: the "creepage" distance along surfaces and the "clearance" distance through air between the two sides, plus proper insulation in the transformer itself.

When Electrical Safety First commissioned the test lab Nemko to dismantle counterfeit chargers, it reported "inadequate or zero spacing (creepage distance and clearance) between primary and secondary windings" and missing insulation layers. A charger built like that can work perfectly for months. It fails when a surge, a drop or ordinary ageing closes the gap — and at that point mains voltage can reach the USB output, or the part overheats and catches fire.

The protection circuits you cannot see are the second problem. Good chargers shut down when they overheat or when the output is shorted. Which?'s testers found cheap chargers with no thermal protection at all.

What the labs keep finding

Three independent rounds of testing, a decade apart, point the same way.

In the Electrical Safety First study, carried out in 2015, 58 % of the 64 chargers failed the electric strength test that checks insulation, 83 % failed on required markings, and 64 % carried fraudulent safety approval marks. Underwriters Laboratories, testing 400 counterfeit iPhone chargers bought in the US, China and Australia in 2016, found that only three passed the electric strength test.

The most recent round is the most instructive, because it shows the problem has moved rather than faded. In June 2026 Which? bought 15 USB chargers from marketplaces including Amazon and Amazon Haul, AliExpress, eBay, Shein, Temu, B&Q Marketplace and Debenhams. Nine posed a risk of electric shock and eight a risk of fire. A fake Apple adapter bought on eBay for £11.99 "failed all of our electrical safety tests with arcing being heard after 10 seconds". The one clear pattern was the absence of paperwork: every one of the 15 was missing legally required markings, importer details or documentation.

Europe's rapid alert system is seeing the same flow. Safety Gate logged 4,671 alerts about dangerous products in 2025, the most since it began in 2003, with electrical appliances among the top three categories and China the origin of 43 % of notifications.

Before you buy

Almost all the value in this guide sits here, because once a charger is in your hand the most important parts are sealed inside it.

1. Buy from the brand or an established retailer, not a third-party marketplace seller. That is the first piece of advice from both Which? and Electrical Safety First. On a marketplace, check who the seller is, not just whose logo is in the photo.
2. Distrust a big-brand price that is too good. Which? singles out "very cheap big-brand chargers" as the likeliest counterfeits. A generic charger from an unknown brand is not automatically dangerous; a fake of a famous one is dishonest from the start.
3. Buy the wattage you actually need rather than the biggest number in the listing. The USB-C guide explains how to match a charger to your devices.
4. Look for a named company with an address. Products sold in the UK must show the details of the importer; in the EU, a manufacturer and an address in the EU. A listing that cannot tell you who makes the thing is a listing to skip.

Reading the markings

Markings are the one part of the safety story you can check without tools, but they need reading carefully.

CE and UKCA. A charger sold in the EU needs a CE mark, and in Great Britain a CE or UKCA mark. Their absence is decisive: Which? notes that without one or the other a charger "can't be sold legally in the UK". Their presence is much weaker evidence, because both are declarations by the manufacturer. In the Commission's words, "by affixing the CE marking to a product, a manufacturer declares that the product meets all the legal requirements". Nobody inspected it on the way in, and counterfeiters print the mark as freely as the logo.

Third-party marks. Marks from testing bodies — UL or ETL in North America, for example — mean an independent lab assessed the design, and they come with a file number you can look up in the certifier's public database. A mark with no traceable number, or a number that belongs to a different product, is a strong sign of a fake.

The rating label. A genuine charger prints its input range (for example 100–240 V) and its output voltages and currents. Missing ratings, misspellings, smudged printing and a label that does not match the product photo are all on Electrical Safety First's list of tells.

Checks in your hand

None of these proves a charger is safe; each one that fails is a reason to stop. They are drawn mainly from Electrical Safety First's guidance on counterfeit Apple chargers, and they generalise well.

Pins. Counterfeit plug pins are often "metal-coated hollow plastic, rather than the solid metal used in genuine products", according to Electrical Safety First; in its study, 15 chargers — 94 % of those put through the pin strength test — failed it, some pins snapping off. Pins that are the wrong size or spacing may also make poor contact in the socket and overheat. For UK plugs, the charity publishes an online plug checker.

Weight. A charger stripped of its safety components is light, and a feather-light plug is still a fair warning. But the old rule of thumb that a heavy charger is a genuine one has been broken on purpose: Which? opened chargers in 2026 and found modelling clay packed into two of them and a metal weight in another, to make them "feel more substantial".

Cables. For Lightning cables, Apple publishes a detailed guide to counterfeits: genuine connectors are one smooth piece with rounded contacts, and the cable carries printed text and a 12-digit serial number about seven inches from the USB end. For USB-C cables, the wattage rules matter as much as authenticity.

Warning signs in use

Electrical Safety First's list is short, and every item on it means the same thing: unplug at the wall and stop using the charger.

• "burn marks, sounds of 'arcing' (buzzing or crackling)", or a case that "feels too hot to touch";
• "odd smells or any sparking or smoke";
• "any swelling, cracks or damage".

Warm is normal, especially for a fast charger working hard. Too hot to keep your hand on is not. The same charity advises not leaving USB chargers running overnight or while you are out, and keeping them away from heat, sunlight and water — sensible habits that also help the battery.

If you think you have one

Stop using it; a suspect charger is not worth keeping as a spare. If you bought it recently, return it to the seller: a product that does not meet the rules is not of satisfactory quality, and in the UK Which? points buyers to their rights under the Consumer Rights Act 2015 if the return window has passed. Report the listing to the marketplace, and in the UK to Trading Standards through Citizens Advice; in the EU, national market surveillance authorities feed the Safety Gate system.

Then replace it with something boring from somewhere accountable. A charger is one of the cheapest parts of the setup and the only one plugged directly into the mains. It is the wrong place to save the last few euros.

Sources

• Which? — Dangerous phone chargers for sale on online marketplaces (June 2026)
• Which? — Chargers, travel adaptors and power banks on online marketplaces (September 2019)
• Electrical Safety First — Counterfeit and imitation Apple chargers (2015 study with Nemko)
• Electrical Safety First — How to spot a fake Apple charger
• Electrical Safety First — USB charger safety
• AppleInsider — UL testing of 400 counterfeit iPhone chargers (December 2016)
• European Commission — CE marking
• Euronews — Safety Gate 2025 report
• Apple Support — Identify counterfeit or uncertified Lightning connector accessories