In a statement sent to newsrooms, Kenya Power said supply was restored by 7.50am.
West Kenya and North Rift Regions were not affected by the blackout as they were on supply from Turkwel, Sondu and Sang’oro power stations and from Uganda.
“The partial blackout was due to a major system disturbance on the Olkaria-Nairobi 220kV transmission line,” the statement indicated.
The cause of the blackout was under investigation through log analysis and physical inspection of the line.
At the time of the outage, the Olkaria line was carrying 63 percent equivalent to 540 Megawatts of demand at the time.
“Kenya Power apologises for the inconvenienced caused by the power supply interruption, “said the company.