* Two transmission lines fail, knocking off national grid
* Blackouts cited as key barrier to economic growth (Releads with power restored to most parts)
By James Macharia
NAIROBI, May 28 (Reuters) - Kenya’s power grid failed on Tuesday, plunging east Africa’s biggest economy into a blackout for about five hours before it was restored to most parts, sole power distributor Kenya Power said.
Kenya Power supplies 1,250 megawatts of electricity to more than 2 million customers connected on the national grid, against demand of 1,700 megawatts, with most of the fuel generated from hydro power stations run by KenGen.
The company said two transmission lines carrying 400 megawatts (MW) of electricity from a geothermal power source in the Rift Valley, where KenGen is tapping vast reserves of steam energy in a geologically active region, failed.
This set up a ripple effect, knocking out the national interconnected grid and generating system - which relies on hydro-power for the lion’s share of its electricity - leading to a national power outage, the company said.
Noisy generators thundered in the capital Nairobi, as businesses and some homes relied on diesel-powered generators. Electricity was however restored before darkness fell.
“By 6 pm (1500 GMT), electricity supply to 90 percent of the country had been restored,” said Gregory Ngahu, a Kenya Power communication officer said.
Ngahu said the company had tapped power from neighbouring Uganda’s national grid, to which Kenya’s grid is already connected, in order to jump-start the national grid.
Businesses in the country of 40 million people often rely on diesel generators to make up the gap between power demand and output and cite frequent localised power blackouts as one of the key barriers to economic growth. (Additional reporting by Kevin Mwanza; editing by James Jukwey)