EPHRATA — A closed switch on a battery charger at a Grant County PUD substation led to a spectacular explosion and electrical outage that cut power to the Ephrata-Quincy area Feb. 17. The closed switch was determined to be human error.

“We went through a pretty extensive investigation,” said Ty Ehrman, a member of the investigation team. The investigation couldn’t determine what caused the original interruption, which occurred in a residential neighborhood in Ephrata.

Whatever caused it, the electrical arcing on the power line at the intersection of Elm and C streets went on for about three minutes. In electrical generation “three minutes is pretty much an eternity.”

The electrical interruption traveled back down the power line to the substation, located on Nat Washington Way. The result was a spectacular display of electricity’s power. “Lots of arcing, lots of sparking, lots of damage,” Ehrman said.

The damage is expected to cost the district somewhere between $4.5 to $7.5 million to repair. The power went out in Ephrata, Quincy and Soap Lake, overnight in some areas, affecting as many as 8,000 customers.

Vehicles that were parked next to the substation were damaged in the explosion and ensuing blaze; fire also damaged a nearby maintenance building. As the interruption traveled further along the system, it was shut down at the next two substations down the line, the Columbia substation between Ephrata and Quincy and at Rocky Ford.

The residential lines are equipped with circuit breakers, just for a situation like the one that occurred Feb. 17, Ehrman said. The transformers at the substations also have systems designed to shut off the power in the case of an interruption. But that night both failed to work, he said.

The safety systems are powered by batteries, which ensures they will work if the electricity goes out. However, Ehrman said, the system that charges the batteries had been disconnected about eight weeks earlier. That meant the safety systems monitoring the residential line and at the substation didn’t have enough power to work properly.

He said it was determined that somebody – the investigation didn’t determine who – disconnected the battery charger. While the investigation didn’t determine who disconnected it, Fuhrman said it did determine when it happened, about eight weeks prior to the incident.

Due to the way the system was set up PUD maintenance workers didn’t know it had been turned off, he said. Improving monitoring of the system is one of the recommendations of the investigation team.

About 26 of the PUD’s 54 substations have similar systems, Ehrman said, and the charger has been locked open in all of them.

The investigation team determined that managers and workers alike need to pay more attention to safety and safety procedures beginning with the senior management. The investigation team also recommended reviewing the existing equipment and identifying weaknesses in the system.

Cheryl Schweizer can be reached via email at [email protected].