This also reminds me of advice I give to everyone to whom we sell computers. Whenever you don't know the electrical of a location well, make sure you plug all of the accessories of a particular computer to the same outlets as the computer itself. In the early days of Firewire, many ports used to get fried because people would plug drives into a different outlet than the computer, and in a case like yours, it'd fry things.

Firewire port protection is a bit better these days.