A technical hitch at the Nairobi North Substation in Ndenderu caused power outages in Nairobi, Mt Kenya and Coast regions on Monday morning.
Daniel Tare, Kenya Power network management general manager, said supplies from Olkaria geothermal fields to the city were cut off.
“We regret any inconvenience caused,” he said in a statement.
Kenya Power said last month that the completion of three substations at a cost of Sh18.47 billion ($180.5 million) would reduce blackouts.
Former managing director Ben Chumo said the stations will provide alternative sources in case of outages in Nairobi.
Blackouts consume more than half of the country’s supply of electricity and generate about 70 per cent of the company’s earnings.
In the year to June 30, 2016, Kenya Power completed construction of 36 additional substations across the country in line with its five-year Power Distribution Masterplan that runs up to 2018.