I believe it all depends on the total wattage that you're pushing through the wire. I have a 13w7 with a 500/1 hooked up to it right now and I ran into some problems using 12 awg... the speaker terminal connector on your box will get hot if the wire gauge isn't large enough... heat indicates resistance, so I would start with something like 12 or 10 and see if you have any heat, too much heat and down grade. I would say that 500 and under you're straight with 12, but anything over 500 and you should go a little larger, don't be afraid to go with 8. In my opinion it's better to have too large of wires than too small, you can never let too much power in //content.invisioncic.com/y282845/emoticons/smokin.gif.f1dc8d2acb1809e863ebd6a47eaa0d45.gif
I know a lot more about house wiring than subs though.