Most of Kenya suffered a blackout on Saturday due to a fault on a major transmission line serving the capital Nairobi, electricity distributor Kenya Power said.
By mid-morning supply had been restored to six regions including West Kenya, North Rift and South Nyanza, the company said, but Nairobi remained without power.
"We experienced a technical challenge that led to tripping of our main supply line ... consequently leading to a power outage in most parts of the country," Kenya Power said.
The fault was on a supply line that runs from Olkaria, in the Great Rift Valley region to Nairobi.
Blackouts are common in Kenya, partly because of an ageing energy network and insufficient generation capacity. Many businesses in Nairobi and other big towns operate backup generators.