UPDATE: On Wednesday evening, AEP announced “significant progress” in restoring power to Franklin County and expects to have power restored there by 5 a.m. Thursday. Click here to read more.

COLUMBUS, Ohio (WCMH) – Hundreds of thousands lost power for hours Tuesday in Ohio as AEP tried to mitigate increased usage on its electrical grid after it had been damaged by storms. While AEP Ohio has taken the center stage as its representatives tried to explain why they cut power to customers, it also wasn’t the company’s decision to make.

AEP Ohio shared an impact map during a Wednesday press conference to further explain the outage situation. The company also warned that customers who are still without electricity “should prepare for the outage to potentially continue into Thursday.”

(Courtesy Photo/AEP Ohio)

While AEP Ohio serves as the dominant provider for electricity in the area with nearly 1.5 million customers, it also reports to a regulator above it. That agency, PJM Interconnection, oversees the movement of electricity for 13 states and Washington, D.C., and it monitors the regional power grid conditions while giving orders to electric companies within its borders.

AEP Ohio crews work on a power line that was snapped in half by storms the night of Monday, June 13, 2022. (NBC4 Photo/Anna Hoffman)

Three of AEP Ohio’s high-voltage, 138-kilovolt transmission lines — which serve as major electrical arteries in Columbus — became a focal point as PJM gave orders to start load shedding, or dropping power usage.

“The problem was in the northern side of Columbus on transmission [lines],” said David Ball, AEP Ohio’s Vice President of Energy Delivery Operations. “There are various cause codes as to why those lines were outaged, and the southwestern part of Columbus. And the remaining in-service lines that we had to keep in service to maintain power to everyone in Columbus, those were overloaded, which forced the targeted dropping of customers to alleviate those conditions.”

Scroll through the timeline below to see a breakdown of the warnings and orders related to Columbus’ transmission lines that PJM sent AEP Ohio, sourced from the regulator’s emergency procedure records:

The delivery operations representative also elaborated on why some transmission lines had to be taken out of service before the overload incident.

“They were either directly damaged by the storm or events that happened after the storm, but everything is related directly to the storm event,” Ball said. “There’s not enough lines in service currently, to bring power into the city.”

It’s not clear if the three transmission lines marked for overloads by PJM were being used to to offset downed lines, or if they were part of the knocked-out group of lines. As an example of the coverage the lines provide, AEP’s map below shows the distance the Marion-Obetz line travels through the city.

At the outage’s peak at 9:15 p.m. Tuesday, as many as 240,445 AEP Ohio customers had lost power according to AEP’s outage map. The utility provider later provided a timeline of when people in each region could expect their power to come back on, and its map showed a decreasing number of customers around 60,991 without power at 10:22 a.m. Wednesday. However, the number of customers without power on the map shot back up to 116,620 as of 12:15 p.m.