If it has 50, it will have 30 also. They list it so you can determine if they have what you need. Our camper is 50 amp, so I will always check to see if they have that available when we are looking for a campground. I don't think there is a device to step it down, but if there is 50 amp service, the next connector in the box should be a 30 amp. Some of them even have a 15 amp household type plug at the power pole.