Dubois power outage caused by a broken cross arm on main transmission line; Breaker tripped twice
(Burris, Wyo.) – A broken cross-arm on the main transmission line between Riverton and Dubois was the cause of not one, but two power outages Sunday evening that impacted some 1,100 customers from Crowheart to Dubois and beyond.
“A bolt sheared off (a crossarm) and when it rained, the power tracked to ground with the water and opened up the breaker,” said High Plains Power Company General Manager Jeff Hohn Monday afternoon. “The incident occurred east of the Burris substation.”
High Plains’ Dubois Foreman Doug Cooley said the line cleared itself and when the breaker was reset, it stayed on for another 45 minutes, and then moisture caused the breaker to open up again. At that point, crews had to remove and replace the crossbar. Asked why a bolt would shear off, Cooley said it was only a matter of time. “That line was last put in in the 1960s, so it’s been there for a long time with years of heavy snow load and wind and it just wore it down,” he said.
Hohn said that transmission line is on the schedule for replacement “in a few years” as part of the company’s maintenance plan.
When asked about power surges when the power was restored, Cooley said there should not have been any. “We bring the power back on line real slow to keep from doing harm to our customers,” he said. “Anyone that had a surge protector damaged should probably look at the manufacture of that device, it most likely failed.”
Cooley did say there were several “brown outs” along the line from Crowheart to the Lander area, but they were not significant.
The crossbar on a power pole that failed was located some 30 miles east of Dubois.
Hohn did note that High Plains is in the midst of a major under-grounding project in the town of Dubois to upgrade and improve service there.