Generally, you want to keep the spans of overhead conductors of services at least three feet from anything [230.9]. That distance includes the slack in the conductors.
To avoid problems with achieving this distance when installing a new service, think carefully about the location of the service itself and of the utility connection point. Work with your electric utility's engineering department to determine the best location for both. Ideally, it will be on the opposite side of your building from your parking lot and/or main driveway.
Keep in mind a couple of points:
- Overhead service conductors are exposed to ice, wind, and other possible sources of interruption that underground conductors are not.
- Underground conductors aren't supported by poles that people can drive vehicles into.
If the electric utility's distribution to your property is overhead, that doesn't necessarily mean you must run overhead service conductors. It's worthwhile to consider a pad-mounted disconnect and/or transformers for the electric utility to connect to, and from there you'd run the service conductors underground.
If the electric utility's distribution to your property is underground, it makes sense to preserve the protection afforded buried conductors. Unless there's a strong reason not to go with service laterals (underground conductors between the utility electric supply and the premises supply point), don't change this to an overhead configuration with the service conductors.