Electric power transmission is the bulk transfer of
electrical energy, from generating
power plants to
electrical substations located near demand centers. This is distinct from the local wiring between high-voltage substations and customers, which is typically referred to as
electric power distribution. Transmission lines, when interconnected with each other, become transmission networks. The combined transmission and distribution network is known as the "
power grid" in
North America, or just "the grid". In the
United Kingdom, the network is known as the "National Grid".