After connecting my Cam 2 to its included power adapter through a 20 foot USB cable, it frequently would not stay connected. I had to power it down and up again to get it to reconnect. The solution was simple: I replaced the included 1000 milliamp power adapter with one that is 2000 milliamps. No more problems.
That only sometimes helps since the main problem is voltage drop that is due to resistance and not particularly helped by the increased amperage potential. But thicker cabling helps.
A closer outlet would be the best option. USB A was never intended for runs longer than 10 feet.