To get some clarity on that, we spoke with John Drengenberg, consumer safety director at UL (Underwriters Laboratories). UL sets the standards for safety on many electronics devices. Drengenberg said that the company does have internal and external temperature standards for chargers.
When we asked for a specific surface temperature that such devices should not exceed, Drengenberg said that UL's external temperature limits vary based on the materials used for the power supply's enclosure.
"I can tell you from my years of working in the lab that I can barely keep my fingers on a product that is at 55 degrees Celsius [131° Fahrenheit]," he said. "My threshold of pain is right there. Now is that a fire hazard or a shock hazard? I don’t know."
Because the HP Chromebook 11 charger was UL-listed, Drengenberg said that he expected UL also will be conducting an investigation. As for the advice from HP and Google to simply use another charger, we tried that, with varying results.
Charging flexibility was supposed to be one of the original selling points of the Chromebook 11—because it uses the same charging standard as many other devices, you only need to bring along one charger when you're on the road. But the Chromebook 11's charger is rated for an unusually high 3.0 amps, and when we plugged in a lower-amperage microUSB charger from another device, we got a message on the Chromebook that said: "Low-power charger connected. Your Chromebook may not charge while it is turned on." So as far as we're concerned, that's definitely not a long-term solution.
Whatever the case, we hope HP, Google, the CPSC, and UL get this sorted out soon. Nobody seems to be offering refunds on the Chromebook 11, and if the chargers from other devices don't deliver enough juice to power the HP Chromebook for normal use, it seems like a severely hobbled machine.