Ac wires are not suited for this application because they are thin. They are designed to carry only 15-30A load@ 120 Volts. You need a special wire that specifically designed to work with high loads. Go to specialty car audio shops and look around. They are extremely expensive, usually ranging from $1.60-10.00/ft depending on gauge size. Please compare AC wire and DC wire cross- sections. The cross-section of Ac wires is not sufficient to carry high-load circuits.
Adam, it is true that you will have a more significant voltage drop when running a long 12v DC cable. That is why you need higher gauge size to reduce this voltage drop over the long distances. That is why it is very crucial to calculate your circuit voltage drops before you go and spend $8.00/ft Stinger or StreetWire power wire.
It's very important to estiblish the relashionship between: Distance (ft),WATTs (load),Voltage (V), and Currency(Amps)to properly calulate the wire size.
And you don't, you are beggin for disaster.
P.S. Jshrieve, Volts don't kill people; Current kills people!