In its capacity of France's transmission system operator, RTE is a public utility whose role is to supply electricity around the clock, providing the same quality of service across the country with the support of its 9,500 employees. Every second of the day, RTE controls power flows while constantly balancing supply and demand. RTE maintains and expands the capacity of the high and ultra-high voltage grid (ranging from 63 000 to 400 000 volts) amounting to almost 100 000 kilometres of overhead lines, 7,000 kilometres of underground lines, 2,900 solely operated or jointly operated substations and 51 cross-border lines. France's power grid - the most extensive in Europe - is interconnected with 33 countries. As a neutral and independent key industrial player in the energy transition, RTE is optimising and transforming its grid with a view to accommodating more power generation facilities, irrespective of future energy choices. The public authorities rely on RTE's technical expertise and reports to inform their decisions.