Normally it is 30 amps for copper. Not sure if aluminum but less. If you go to long run (like 100 feet) it will drop. Are you running a 110 or 220 circuit or do you need both? If you are trying to run a 110/220 circuit you need 10-3 with ground and not 10-2. Don't miss the insulation factor either, if running for camper suspect this will be outside and be either in conduit or buried or both.