After five weeks without power, New Zealand's largest city saw the light again Friday when a new emergency cable was flicked on. But hours later, the cable failed, trapping people in elevators and snarling traffic.The foul-up was remedied later in the day but not before causing confusion and embarrassment.

"Our timing couldn't be much worse," said Patrick Strange, planning director of the city utility Mercury Energy.

A faulty sensor on the new cable that was "too finely tuned" tripped a circuit breaker and shut off the line, Mercury Energy said. By the end of the afternoon it had been fixed and the line was back in service.

"I guess the beast gave one final flick of its tail. This time we'll put daggers through its heart," he said.

About a fourth of downtown, including the University of Auckland and nearby high-rise office buildings, was blacked out for much of the day.

"It was like the world had changed, instantaneously," said Bernard Griffen, who was in a downtown store when the power failed.

"The lights went out, there were no computers, no tills, no scanners, no lights. It was really weird. The music went off and people started talking really quietly."

Traffic lights stopped working, and firefighters rescued six people trapped in elevators.

The managing director of the ASB Bank, Ralph Norris, hiked down 28 floors from his office after the power failure knocked out the elevators, lights and computers.

"If you don't laugh about these things . . . " he said.

The new, temporary cable was supposed to end the outage that began Feb. 20, after the four main power cables feeding Auckland failed. The temporary power line will be in place until late next year when a tunnel to house new electricity cables is finished.