Hello again mody254, the 2/0 is the "suggested" size for a 100' run at 250 amps. That isn't to say that you can't perform welds at longer lengths with smaller cables and such. You do have to consider voltage drop, heating issues, and other sorts of things when you start getting outside of the recommended sizes and lengths. Using cables that are undersized can physically shorten the lives of them due to the increased heat, the coverings can deteriorate at an faster rate than would be normal. A change in voltage relative to amperage can have an effect on a welding puddle and how the bead "stacks" so to speak. Sometimes this can actually be beneficial, other times it can be disasterous. Hopefully this has given you a bit more to consider, the folks who actually do a considerable amount of this sort of work can possibly supply you with better information about all of the effects that you can expect. Best regards, Allan