When electricity is delivered from your utility company, it comes through to your home's electric panel (breaker box) on the line wire, which is also called the incoming or upstream wire. A distribution board or distribution box is where the main power supply is distributed to multiple loads. And all the switching and protective devices are installed in the. Article 230 of the National Electrical Code (NEC) explains the installation of service conductors and service equipment that brings electrical power from the utility supply to a building or structure. Overhead service wires are called a service drop. The drop runs to a weatherhead atop a length of rigid conduit.