The wires between the bulbs and the ballasts are high voltage. So, I don't think you can just use regular 300 or 600 v wire. Well, you probably could, but it wouldn't be the best idea. On all the HID's I've ever worked with, that 'wire' is a couple of HV wires in a sleeve.

Jriggs...you extended between the bulbs and the ballasts with regular wire?

Toby