A power outage that plunged 50,000 Pacific Power customers, including much of Del Norte County, into darkness late Friday evening into Saturday morning was not related to the weather, a spokesman for the utility said Monday.

The blackout occurred when a 115-kilovolt transmission line was tripped open, cutting power to 18 substations, said Drew Hanson, senior communications representative for PacifiCorp. The utility restored power to three of the 18 substations “fairly quickly,” reducing the number of customers without electricity to 30,000 customers, he said. Power for Del Norte County was restored at about 3 a.m. on Saturday, Hanson said.

One of the substations affected was a transmission statement in Grants Pass, Oregon, Hanson said. The blackout affected cities between Grants Pass and Del Norte County, he said.

According to Hanson, this outage is unique from the one that affected Del Norte on Thursday. Most of Del Norte County lost electricity when a redwood tree fell on a major power line, he said. This left the area without power starting from about noon. Electricity wasn’t completely restored for some customers until about 2 a.m. Friday, Hanson said.

“They would get it back up and something would happen and it would go back down for a little while,” Hanson said Monday. “Those customers seemed to be fairly isolated.”

According to the National Weather Service, gusts on Thursday reached 53 miles per hour in Crescent City at 12:22 p.m.

Meanwhile, upgrades Pacific Power has been making to its transmission system in Southern Oregon has made it more prone to power outages, according to a press release from the utility.

“The ongoing work is necessary to improve the system to keep up with growth,” Christina Kruger, regional business manager for Pacific Power, said in a written statement. “We are a vibrant, growing community and our system needs to keep up with this growth. Right now, we are experiencing some growing pains while we are working on finishing our current reliability projects.”

According to Hanson, the project to upgrade the transmission line and substation in Grants Pass will cost the utility $10 million. He said this work may be behind recent outages in Southern Oregon as well as the Crescent City area. The project is due to be completed in mid-December, Hanson said.

Pacific Power will also break ground on a $70 million upgrade to transmission lines in Southern Oregon and will build a new substation to “further enhance reliability” and manage the area’s growing power needs, according to the press release.

Reach Jessica Cejnar at jcejnar@triplicate.com .