DECATUR - A substation problem triggered a widespread electrical failure in Decatur on Monday night that disrupted power supplies to more than 6,000 customers.

Most of the power problems were concentrated in the west and southwest portions of the city, but AmerenIP outage maps indicated some customers were affected in an area stretching from Warrensburg toward Oakley and south toward Blue Mound.

The power disruptions started around 4:23 p.m., according to AmerenIP, and were not fully restored until 8:17 p.m.

"We had an insulator fail at our Edward Street substation in Decatur," said Ameren spokeswoman Natalie Hemmer. "Equipment just does that from time to time and it's one of those things you can't necessarily test for."

She said power crews were still working to fix that problem late into Monday evening, but power had been restored in the meantime by rerouting supplies.

At the height of the disruption Monday evening, every Decatur Fire Department crew was deployed answering emergency calls triggered by the electrical failure and an extra company was called in for duty.

Battalion Chief Fred Schneller became concerned because the nature of the power failure was that power was not knocked out completely in large areas, but running instead at a reduced level. He feared this could trigger electrical shorts and spark fires if families kept on using appliances as the lights dimmed.

Schneller responded by using Decatur's computer-controlled 911 system to make calls to homes and businesses warning people to turn off appliances until power levels came back to normal.

"Eventually, we ended up making calls in an area from Edward Street south in a straight line all the way to the city limits south, and then from Grand Avenue west to the city limits," Schneller said. "It was that entire quadrant, and I am sure it covered hundreds of buildings."

Schneller said the system worked well but he kept the extra firefighters he summoned on duty until he was sure the situation was back to normal. He said the power failure also triggered many carbon monoxide detectors to go off, which happens when they sense power failures.

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