A commissioned report of 400 fake Apple chargers bought from all over the world found that 99 percent of them were unsafe, and didn't have sufficient safeguards to protect users and plugged-in devices.
According to BBC News, Underwriters Laboratories (UL) applied high voltage to the chargers to test for sufficient insulation and other safeguards. As a result of the testing, the agency concluded that unknown chargers purchased online were an "unknown entity" and hazardous.
The chargers were purchased from vendors in Australia, China, and the U.S.
In October, Apple started stemming the tide of counterfeit chargers, and sued vendor Mobile Star, accusing it of violating copyrights and trademarks by selling counterfeit accessories on Amazon and Groupon. The suit specifically targets 5-watt USB power adapters and Lightning-to-USB cables sold by Mobile Star, the same as those cited in the BBC News report.
Apple said that it discovered the issue with Mobile Star's gear as part of its regular efforts to combat fake accessories.The company notes that in nine months, it bought "well over 100 iPhone devices, Apple power products, and Lightning cables sold as genuine" through Amazon's "Fulfillment by Amazon" program, and found that almost 90 percent of them were inauthentic.
In 2012, engineer Ken Shirriff examined Apple's chargers, and found them to include better and safer components than knock-offs. A year later, Apple implemented a fake charger buy-back program, which appears to still be operating.