4 wire power cords are expensive over 10' in length everywhere I looked. I needed 20' and my solution was to buy 25' of 10awg wire, put the plug Kal recommends on on end and I got a 4 prong plug from eBay for the other. Even though the 4 prong was pricey, by the time you add the wire, prong, and Kal's plug it was still cheaper than getting a custom cord made. And so far it has worked fine. It's a bit stiff, though, as you might imagine, but no biggie. It works.