Driver distance from string

How far away is it possible to have drivers away from the actual string of leds and what is the metric for judging that distance

I'm sure someone will go into more detail. I cannot english right now.

http://www.calculator.net/voltage-drop-calculator.html

The gist of it is that you want to aim for a voltage drop of less than 3%. The guage of the wire is typically the only variable you can adjust. Larger gauge wire can send power further with less voltage drop. There is more explanations at the link.