COLUMBUS, Ohio (WCMH) – AEP Ohio and the regulatory agency over it agreed Thursday that the reason behind a summer power outage was a chance encounter with plant life.

While AEP Ohio markets itself as the dominant power provider in central Ohio with nearly 1.5 million customers, the agency PJM Interconnection oversees the company as well as the movement of electricity for 13 states and Washington D.C. PJM monitors this regional power grid for issues and can give orders to electric companies within its borders.

A presenter during the PJM hearing confirmed that based on the regulator and AEP’s findings, the domino effect on the Columbus-area power grid all started because of power lines that touched vegetation. This caused them to overload, even though they were normally capable of handling the level of power running through, and around 240,000 customers lost power as a result.

Columbus neighborhoods impacted by AEP Ohio’s power outages in mid-June. (Courtesy Photo/AEP Ohio)

AEP Ohio and PJM previously explained part of the problem that sparked a three-day power outage between June 14-16. A prolonged thunderstorm with strong winds — known as a derecho — battered central Ohio and AEP’s power infrastructure. The storm hit AEP particularly hard on the northern side of Columbus and in Marion, said David Ball, AEP Ohio’s Vice President of Energy Delivery Operations, during a mid-outage press conference.

“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.”

An AEP Ohio spokesperson explained to NBC4 what the company had reported to PJM. AEP saw high power consumption on June 12, but its seven transmission lines where the problem stemmed from were rated to handle the electrical load. It wasn’t until after the derecho storm that a new issue altered the lines.

“Highly loaded transmission lines will hang lower or ‘sag’ … The severity of the June 13 derecho storm caused changes in the landscape and displaced trees. The day after the storm, transmission lines carrying similar load levels as June 12 sagged into trees and vegetation, causing outages.”

AEP Ohio

Those seven high-voltage transmission lines tripped on the first day, June 14. Then, three of AEP Ohio’s 138-kilovolt lines — which serve as major arteries for delivering power in Columbus — became focal points as PJM gave orders to start load shedding, or dropping power usage.

“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,” Ball said.

During the presentation on the outage incident, a PJM spokesman said the regulator had recommended to AEP that it should “improve vegetation management practices.” AEP Ohio told NBC4 it had since employed new technology to do so.

An example of an image created with a LiDAR sensor. (Courtesy Photo/U.S. Geological Survey)

AEP … is using advanced laser aerial evaluation (LiDAR – Light Detection and Ranging) and expanded visual inspection of the transmission lines delivering power into Columbus to reduce the potential impact of future severe storm events on our system. We have fixed any damage or hazards we discovered.

AEP Ohio

Attendees at PJM’s hearing asked if the regulator had sent any investigators to the sites where vegetation was cited as the cause. The presenter responded that instead, they took the word of AEP, who conducted their own assessment of the power lines and determined contact with plants as the cause. The agency did, however, conduct a “lengthy interview process” with any of AEP’s staff or engineers who were in the company’s power control room during the outage event. Regulators used this to create a timeline of the event and record what actions AEP took in response.

The Ohio Consumers’ Counsel also had representatives present for the PJM hearing. The group previously filed a motion with the Public Utilities Commission of Ohio to ask for an independent investigation and damages determination for the June outages. However, an OCC representative told NBC4 that five months later, PUCO has yet to follow up with a ruling.