On Tuesday, June 6, 2017 at 10:37:08 PM UTC-4, wrote:
The reply from "Hub" that the voltage did not matter is wrong. If you had a supply voltage of 24 Volts, and a 10 Volt drop in the power cord, that would be pretty much a loser. The same 10 Volt drop at 120 Volts would not be an issue under reasonable circumstances.

Agree, the effect you describe is correct. From a practical standpoint, he's likely talking about 120v and I'd go with 10g. I've seen plenty of motors struggle, overheat, trip breakers on smaller cords, while they run fine on a heavy one.