Any analog CCTV camera by nature runs signals on RG59 or RG6, and power in dual 18 gauge power leads. Have a look for what they call siamese cable which looks just like dual RG6, except 1 cable is rg59 or rg6 and the other is a dual 18gauge power cable. That cable will do just about any camera w/night vision LED's and most PTZ as well. At most, any of them will only pull about 1amp max, more commonly 500mA. There will always be exceptions to the rule, but generally speaking 18gauge is all you need for the power.
Also, most of the passive baluns out there too are only small gauge cable for power...its really all you need.