Service entrance drops are used to supply power to your home. They can be fed overhead or underground from the utility company’s power pole. In either case, a hot primary feed and a neutral feed are run from the utility company’s line to their transformer. From there, the transformer feeds two hot wires and a neutral to the service drop, either overhead or underground.
Overhead and underground service entrances are both acceptable, though you may or may not have a choice as to which you have. Many new developments will have underground service entrances, and if an existing home has a service change, the utility company will do the labor and likely decide where the service entrance is.
Overhead connections are above the ground and noticeable, whereas underground service feeds are very pleasing to the eye. There are dangers associated with both of these installations. Overhead wires can be a hazard for farm implements and tall trucks like dump trucks. There is also the danger of metal ladders and overhead wires. Underground wires have their dangers also. Having buried wires in the ground can leave the possibility of digging dangers. A great thing to do when the direct burial cable is installed is to make a map of the trenched line and take a picture, for future reference.
Overhead service entrance feeds are fed through a weatherhead that is attached to a rigid metal conduit. This conduit runs through the home’s eave and the roof of the home for an overhead feed. The penetration is sealed with a roof boot to keep the roof penetration from leaking. The other end of the conduit is attached to the electrical meter, which connects to a weatherproof disconnect and then to the electrical panel. The connection at the weatherhead should extend at least 2 to 3 feet above the roofline. The eave should not extend any farther than 4 feet from the side of the feeder conduit. The service riser should be at least 10 feet above the ground grade.
It is also advisable to use support braces to help support the service riser conduit. Don’t forget to strap the conduit under the eave between the underside of the eave and the top of the electrical meter. These straps should be placed every 3 feet from the electrical meter on up. And one more thing to remember, don’t forget that the minimum driveway clearance should be 12 feet.
Underground service entrance feeds are fed, like their names imply, underground. Instead of overhead aerial cable feeding an overhead service conduit, an underground service is fed by underground, direct burial cable. This method has become the choice of many, replacing the unsightly overhead feeds.
Like its overhead feed, the underground feeder wire has three conductors. It too has two hot wires and a neutral wire. The feeder wire is attached to the transformer and is fed through a conduit or PVC conduit sleeve attached to the utility company’s power pole. The conduit should extend below the ground so the cables cannot be damaged. The underground feed should be trenched at least 4 feet underground. These cables run to the area where the meter is attached to the home. The meter will have a conduit extending from the meter into and below the ground. The feeder wires will again be protected by the conduit from damage that could occur from things like mowers and weed trimmers. Since there are no overhead wires, there is no overhead wire danger with this installation.
Source: The Spruce