ElectriCities customers in Cornelius will experience a planned power outage overnight May 19-20 while the power company installs a new transformer, breakers, regulators, relays and other equipment at the Mt. Zion substation. The work follows a substation fire last November that damaged the equipment and left some Cornelius residents without power for nearly 20 hours.

The Nov. 14 power outage that knocked out power to parts of Davidson and Cornelius started overnight when a voltage regulator at the Mt. Zion electrical substation exploded, shooting oil and fire 20 to 30 feet around the regulator, according to ElectriCities officials. That oil and fire burned a substation transformer, melted wires and damaged other equipment, requiring crews to rebuild about 2/3 of the station.

As a temporary fix, crews installed a used, replacement transformer on loan from Concord Electric. At the time, it was unclear whether the damages to the burned transformer were fixable, or if the town would need to look into purchasing a new transformer – a $570,000 cost. Fortunately, crews were able to repair the original transformer for significantly less money (less than $100,000) and it will be reinstalled at the substation May 20.

In addition to installing the repaired transformer, the town will keep the current transformer for use as a backup, in case the main transformer should fail in the future. The town bought the used transformer for $85,000, bringing the total costs associated with the Nov. 14 explosion to about $360,000, according to ElectriCities General Manager Craig Norfolk. That estimate includes costs for transporting the 35-ton transformer from Concord to Cornelius ($25,000) and repairs to the transformer and substation, as well as the purchase of the used transformer.

The electric company operates and maintains the system, but the town owns all of the assets, so the cost to repair and replace equipment will be paid out of the town’s electric fund. The electric fund is separate from the town’s general fund, Finance Director Jackie Huffman said, and only Cornelius electric customers pay for it. The town also expects some reimbursement from insurance, she said, but the amount is not yet known.

ElectriCities officials will shut off power around midnight Sunday morning, May 20, and expect the outage to last no more than eight hours.

ElectriCities customers received notification of the power outage by bill insert, and notifications also have been placed on the Town of Cornelius website and ElectriCities website. And officials will use the Town of Cornelius reverse 911 notification system to leave pre-recorded phone messages regarding the power outage.

The ElectriCities office will be fully staffed during the power outage, officials say. Customer service representatives can be reached by calling 704-948-0550 for additional information and updates during the outage.

“We apologize in advance for the inconvenience this will cause our customers,” Mr. Norfolk said in a news release. “This work is necessary to upgrade equipment in the substation and ultimately improve service to our customers.”

The power outage will only affect ElectriCities customers in Cornelius, he said.