I'm trying to get 110 service to my pier and I have a 220v pump with a contact switch junction box. I'm trying to catch one leg of the 220 but the junction and pump only have 2-110 hots and a ground .. no common. For several reasons, running a separate line / common is not practical so I'm looking for options. It appears I can run a transformer that will create an "independent" common but I'm not certain I can create a common and successfully output to 110v GFCI. All of this is weather / wet exposed. Any guidance would be appreciated!