JACKSON - A faulty fuse in a protective relay device was blamed for a one-hour power outage that darkened Jackson late Wednesday and early Thursday.

The power went off at 11:30 p.m. and was restored at 12:30 a.m. All 4,500 customers of the city-owned power and light department were affected by the power outage.

City Administrator Carl Talley said the relay serves as a protective device for a 5-megawatt transformer at the power and light department's industrial substation at Jackson Boulevard and Highway 25.

"We're not sure what caused the fuse to fail," said Talley. "It could have been damage from past storms or wear and tear. It just happens from time to time."

When the fuse failed, the relay automatically cut off electricity feeding into the substation from a 34.5-kilovolt transmission line.

Talley said power was restored by isolating the transformer from the rest of the city's power grid.

He said it took a little longer than usual to restore power because of the time of night. "We had to call people out, then they had to track down the source of the problem, and isolate the transformer," Talley said. "In the middle of the night, that takes a while."

He said repairs to the relay were under way Thursday.

Talley said the blackout was not connected to the vandalism of 24 Jackson school buses. "We have nothing at this time to indicate the two incidents were related," he said. "It was just coincidental that they occurred late at night."

Jackson Police Chief Larry Koenig said the power failure set off burglar and security alarms in the city. All had to be checked out. The police station switched to emergency power automatically when the outage occurred.