At the end of 2005, Koeberg started experiencing numerous technical difficulties. On 11 November 2005, a fault on a transmission busbar caused the reactor to go into safe mode, cutting supply to most of the Western Cape for about two hours. On 16 November a fire under a 400 kV transmission line caused the line to trip, causing severe voltage dips which resulted in Koeberg once again shutting down. Various parts of the Cape were left without electricity for hours at a time. On the evening of 23 November, a routine inspection of the backup safety system revealed a below-spec concentration of an important chemical, resulting in a controlled shutdown of the reactor. Due to the sufficiency of backup supply, major power cuts were not experienced until Friday 25 November, when the backup capacity began running out. At this point, rotational load shedding was employed, with customers being switched off in stages for most of the day. Koeberg was re-synchronised to the national grid on Saturday 26 November.