A customer ask me about running a overhead drop to some outdoor lighting at his auto garage. Other than the code requirements for an exhisting service entrance drop, I'm not sure if it is even legal to do this. The other option is to cut out the cement and go underground of course.
The Golden Rule - "The man with the gold makes the rule"
Several times recently we have used overhead drops to feed other buildings off of a main building. We took Triplex overhead to feed a subpanel in the new building and grounded the new building at its disconnect. Each time the jobs were inspected and passed without question.
Depending on the type of facility, and if there are signs on the site, you may want to refer to the National Electrical Safety Code. There are clearance considerations and tables available.
