Q. I see that generic tablet chargers often cost less than ones sold by the manufacturer. But do they work?

A. “Some cheaper third-party chargers can not only hurt your electronics—they can hurt you,” says Maria Rerecich, director of electronics product testing at CR. While the chargers for your phone, tablet, and laptop may seem simple—just a cord and a power adapter brick that plugs into the wall—they’re anything but.

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That brick is packed full with circuitry designed to convert the alternating current (AC) from the wall outlet into the direct current (DC) needed to safely charge the lithium-ion battery in your device. This demanding role is why chargers can feel warm during daily use.

Chargers that come from the manufacturer are designed for your tablet, and they have quality components that go through rigorous testing by UL (Underwriters Laboratories), a global independent safety science company. Because the UL standards are voluntary, many generic chargers without the UL mark use inferior components that don’t meet these standards. And others apply counterfeit marks—go to UL.com/marks to verify yours.

According to Paul Brown, vice president of intellectual property and litigation at UL, these third-party chargers can start a fire; they’ve sparked during tests. In extreme cases they are also an electrocution hazard: In 2014, a woman in Australia allegedly died by electrocution while on a phone plugged into an uncertified adapter, according to a UL report.

Though not all generic chargers are dangerous, it’s worth buying a manufacturer’s charger or one recommended by the manufacturer with a UL seal. “Think of the extra money you spend on a quality charger from a reputable source as an insurance for you, your family, and devices,” Rerecich says.

For related information, check our tablet buying guide and ratings.

Editor’s Note: This article also appeared in the December 2017 issue of Consumer Reports magazine.