doubleofive said:
I'm not 100% sure, but if its powered over the USB I don't think it will draw much more than your computer does when its plugged in.
Actually only the 2.5" USB discs are powered from USB, the 3.5" USB discs need a "normal" external power supply.
I had a "small" fire here a couple of years ago so since then I'm very careful :)