I have 220v to my well house but need to install a 120v convenience receptacle for maintenance tools. The feed coming from my main panel is direct burial. What can I do ?
I think the question is what can I do without running a new line?
My question is do you have a grounding wire with the 220V? Because if you don't you are going to have to ground that circuit also.
Other than that you could set a small panel, split your circuits and add a buck transformer to provide you with 120V from your 220V feeder, and your going to have to ground one secondary side of the line. If you are using an autotransformer configuration the ground should be on the isolated phase of the secondary.
If all of this is a little much experience wise, I would recommend you contact a licensed electrician.
If your wire is 4-wire (L1+L2+N+E) just connect the N wire if you don't want to replace current wire you could:
install a step-down transformer (you should connect also to ground one of secondary coils and add a breaker on the secondary) fit earthing pole, and just use the current PE conductor as neutral (it was allowed till about mid 90's, at least for ovens).