Businesses in electricity production and distribution generate electricity and move it through the networks that supply homes, businesses and public services. Generation may use renewable sources such as wind, solar and hydro power, or other sources including nuclear and gas. Operators manage generating equipment and supporting systems, monitor output and arrange maintenance to keep facilities working safely and reliably. Transmission companies carry electricity over high-voltage networks from generating sites to regional networks. Distribution network operators then deliver it through lower-voltage lines to homes and other premises. Their work can include maintaining cables, substations and transformers, restoring supplies after faults, connecting new developments and supporting changes such as the connection of renewable generation or electric vehicle charging points. The sector is regulated by Ofgem, and electricity network operators and generators may require relevant licences.