Airport Extreme 6th Gen USB Port

[k3rast4se]

I recently bought an Airport Extreme 6th Gen and I would like to connect an external hdd to the usb port. Here's my question. My HDD is a WD Blue 2.5 320GB connected to a external hdd enclosure. This enclosure feature a usb cable with a double usb plug dongle. Is it okay if I only plug 1 usb cable in the airport extreme (only as 1 plug) or will it draw too much current? I don't want to damage my router.

 

[priitv8]

You won't damage your router (it will shut the USB port down if it's overloaded), but if supplied current is insufficient to spin up the HDD, it won't start either.
Normally, 2.5" drives should be good with single USB supply (500mA).