One time it happened in Australia, who investigated the cause thoroughly:
> We know absolutely that the charger itself failed, and that it arced between the 240 volt input and the five volt output. So that's definitive," said Lynelle Collins of NSW Fair Trading. "We've got photos, we've got proof that's been dismantled, so we know that the charger failed.
https://www.vice.com/en_au/article/pa5mng/a-16-year-old-has-...
One time it happened in Australia, who investigated the cause thoroughly:
> We know absolutely that the charger itself failed, and that it arced between the 240 volt input and the five volt output. So that's definitive," said Lynelle Collins of NSW Fair Trading. "We've got photos, we've got proof that's been dismantled, so we know that the charger failed.