oldsewnsew

The longer the cord, and the smaller the guage, you can waste some power in the form of heat. More of a concern with higher power items, like the iron, a hair dryer, a heater, a microwave or toaster, etc. Small items like non-commercial sewing machines, light bulbs , etc aren't usually adding up to enough to cause a problem. A 15 amp breaker, you can multiply times the 120 volts and get what the Maximum load can be to trip the CB. But you wouldnt really want to load that heavily, maybe half that.