Quote Originally Posted by Sea Horse View Post
Plugging into two 30 amp 125 V power will not give you more than 208 volts just like plugging into the 50 amp dock outlet may give 50 amp service but still only 208 volts. I have no idea why they make and sell this device and feel like I was taken since it clearly says on the splitter that it will take two 125 v lines and boost it to 240 v with 30 amp service but higher voltage.
Just a mathematical observation: 125 + 125 = 250. So 240 would not be a "boost."

You're misreading what the product says. All it can do is combine two opposing phases of 125V. It's not a booster or transformer. It's only capable of doing what already exists in a 250V 50A power supply. It's made for situations where a marina doesn't have 50A service, but you can find two opposing 30A services and combine them. The device also prevents you from pushing 60A (30+30=60) through 50 amp wiring and starting a fire.

Your marina's problem is that it's using two phases from 3 phase power which are not perfectly opposed, whereas single phase 250 has two legs that are perfectly opposed so you get full voltage when you combine them.

P.S. Don't ask how three legs of power is three phase and two legs is single phase. I find it very frustrating too.