ext usb drives, powered by port?

There are cases available without power supplies, which use the USB
connection to power 2.5" drives.

Does this endanger the port? Is there a fuse that requires depot
replacement?

 

There are cases available without power supplies, which use the USB

I have a pair of USB (2.0) only enclosures that hold 2.5" (9.5mm thick)
notebook HDDs. I've had 3 different drives in them. 5 gb IBMs, 20 gb
Toshibas, and (now) 60 gb Fujitsus. They get routinely used with 3 different
notebooks and 3 desktops. One of the desk tops. With one exception, all work
perfectly. The exception is that the 20 gb Toshibas drew more current during
spin-up that any of the other drives. One of the notebooks (Dell L400) would
not provide enough current...had to spin the drive up with a battery pack (or
wall wart) before connecting USB. My current 60 gb drives do not require this
on any computer...and they also work fine through a 4-port hub provided there
are no other port-powered devices (like optical mouse) on the hub.

On the one machine that could not spin up the Toshiba drives, there were no
consequences for trying....the drives simply never came on-line.
webpa