‘Short, intermittent outages’ possible in Wyoming during phased power restoration process

CASPER, Wyo. — Black Hills Energy says that Wyoming may experience short, intermittent outages Thursday night as utility companies work to restore to power after widespread outages.

Rocky Mountain Power said over 60,000 customers were affected Thursday starting around 12:43 p.m. Many people reported the power coming and going off again multiple times.

Around 4:30 p.m., the number of customers without power in Casper dropped from about 3,000 to 127, then jumped again to over 500 by the end of the hour. In the Douglas area, there are still about 6,000 customers without power.

As of 5:30 power had effectively been restored to most of Casper.

“The restoration process is complex as our power generation facilities and substations were impacted,” Black Hills Energy said on social media post. “We will use a phased process to restore power which balances system safety and stability.

“During the restoration process, customers may experience short, intermittent outages, such as lights blinking or flickering.”

County offices closed shortly before 2 p.m., and the city of Casper announced it was closing all operations not related to public health and safety at 4:30 p.m.

“The instability of electricity in the region is expected to continue late into the night, and a loss of power after dark could result in unsafe conditions,” the post said. The city anticipates normal operations on Friday.

Two locations were announced for people who are oxygen-dependent and in need of electricity but those location closed at 5 p.m. Anyone experiencing an emergency should call 911. 

Black Hills Energy said the outage was “resulting from an event on the regional transmission grid outside of the Black Hills Energy footprint.”

Western Area Power Administration Public Affairs Specialist Stephen J. Collier told WyoFile they believed the cause was “two tripped 500-kilovolt lines near Medicine Bow, Wyoming.”

Collier said this resulted in “an abnormal voltage event that subsequently tripped a number of surrounding lines, including WAPA transmission, resulting in further power outages to communities across the area,” WyoFile reported.

During an outage, Black Hills Energy recommends the following:

• Keep refrigerator and freezer doors closed to help preserve food.
• Use flashlights instead of candles to avoid fire hazards.
• Don’t use generators indoors or in enclosed spaces.
• Non-functional traffic signals, treat as a four-way stop.