California ends power cuts

People had to be rescued from lifts on Tuesday

California energy officials have ended a series of rolling power cuts that had been expected to last most of Tuesday.

The California Independent Systems Operator (Iso), which manages most of the state's power grid, said voluntary conservation and increased hydro-electric power allowed them to end the controlled blackouts earlier than expected.

The Iso had declared a Stage Three alert at 0920 Pacific time (1720 GMT) and announced a series of 90-minute power cuts that could have lasted until 2000 Pacific time (0400 GMT on Wednesday).

It was the second day in a row that America's richest state had to shut down energy to parts of California for fear of overloading the grid.

Moderate temperatures

An Iso spokesman had warned early on Tuesday that it was going to be "a really bad, really long day".

Police directed traffic by hand

But temperatures were moderate after Monday's record highs caused Californians to turn on their air conditioning.

The state also got help from a power unit in neighbouring Nevada, leading to improved outlooks for Wednesday.

Rolling power cuts on Monday lasted longer and affected more of the state than a round of blackouts in January, and many consumers feared they were a sign of what to expect over the summer.

While the January power cuts affected only northern California and lasted about two hours, Monday's first round of blackouts lasted four hours and took in southern California as well as the north.

It was the third time rolling blackouts have hit the north, following two days of outages on 17 and 18 January.

Historic blackouts

Monday's blackouts were the first statewide power cuts since the Second World War.

They affected everything from traffic lights to Silicon Valley giants such as Sun Microsystems.

The governor is funding more electricity purchases

Warm weather in the south-west, driving up demand for air conditioning power, combined with a transformer fire and a lack of hydropower in the north-west, left California with dangerously low electricity reserves, the Iso said.

The blackouts were called in a desperate last-minute bid to avoid a widespread collapse of the entire electric system.

Iso manages about 75% of the transmission grid serving the state's 34 million residents.

The power grid last ordered rolling blackouts in January when more than 675,000 homes and businesses were affected for more than two hours at a time.

Electricity imports

Hospitals and airports were exempt.

California's energy agency has warned of a power emergency

Power alerts were lifted in February, after several power plants were repaired and more electricity was imported.

But California is anticipating a summer of power shortages and the possibility of further rolling blackouts.

Governor Gray Davis's administration has committed $2.7bn (£1.9bn) - about $45m a day - for power purchases.

That will be repaid when the state issues an estimated $10bn in revenue bonds in May approved for cheaper, long-term power contracts.