Actually, there are 20 amp only Edison outlets out there. Why, I have no idea. They are few and far between but I have seen them. The one that comes to mind is Pfizer's (use to be Wyeth's) Collegeville Campus here in PA. In Campus Commons Dining area, there is one 20 amp outlet and the rest are 15/20 amp right above it. Why it is there, I have no idea. But again, its annoying because I have to drop mult down from upstairs for more power often.