Not sure if you already found what you're looking for but here is a listing for a 14-30 extension cord. It's 30A, 250V, and 10 AWG. Looks like the 10 ft. is out of stock at the moment but there are units in stock for the 25 and 50 ft. The site also has 14-50 and 6-50 cords for EV charging. Hope...