Lights Out Blue Ridge Electric Identifies Cause Of Power Outage By Jerry Sena Blue Ridge Electric Membership Corporation officials have identified the cause of a 32-minute, three-county blackout last Thursday. Spokesperson Renee Whitener said a breaker tripped when a tree made contact with high voltage wires along its right-of-way near the Blue Ridge Parkway. The company provides power to all of Watauga, Ashe and Allegheny counties — some 53,000 customers. The town of Boone, most of which is serviced by New River Light and Power, was affected as well. New River L&P engineering supervisor Len Tester said his company taps into the same 230,000 volt lines that failed Thursday, leaving his 8,000 customers without power too. The outage knocked out every stoplight in Boone, causing traffic jams throughout town. Boone Police were able to post traffic control officers at most major intersections, though many drivers were left to fend for themselves. Boone Police Chief Bill Post said no accidents were reported. Tester said critical operations on the Appalachian State University campus were supplied with electricity from emergency backup generators. The dorms and steam plant are all equipped with generators, as are all the newer buildings on campus, Tester said. Duke Power spokesman Jason Walls had said Friday, the outage originated on a transmission line in the Horse Gap area along the Ashe/Wilkes county line. Whitener said Blue Ridge Electric had assigned 10 linemen and a helicopter to investigate the cause of the power surge. They reportedly found that heat and humidity had caused the lines to sag into a tree that otherwise appeared to have sufficient clearance to avoid contact with the high-tension wires. Whitener called trees the “top threat to power reliability,” because of their potential to cause ground shorts to the transmission lines that deliver power to the high country. “This is especially true during ice or snow storms or when high winds are blowing,” Whitener said, “but can also be true during summer months as experienced last Thursday.” Whitener said customers typically would have experienced barely a glitch, despite the loss of power to one of two major transmission lines that supply the three affected counties. She said backup systems would normally have switched the load to the alternate line leaving technicians time to troubleshoot the malfunction without interrupting power to customers. Thursday afternoon, however, one of the lines had been disabled to allow a contractor to carry out routine maintenance. When the wires on the operating line contacted the trees at about 1:12 Thursday afternoon, the backup had been disabled, leading to the blackout. Whitener said the contractor quickly brought his work to a halt allowing the working circuit back on line. The two lines originate at a Duke transmission station near Antioch. Power company’s spend millions of dollars maintaining rights of way along power transmission lines where trees, shrubs and vines threaten to overgrow and undermine electrical lines. The problem is especially difficult in heavily forested areas such as those in North Carolina’s high country. Many of the rights of way cross private property, complicating the issue even further. And the vegetation control methods used – which range from manual cutting to herbicide spraying – are frequently criticized by environmental groups. The Blue Ridge Electric website states the company uses a “low-volume, backpack application method” to control tree sprout growth beneath power lines. The website states that applying a herbicide mixture directly to selected trees allows low-growing vegetation and wildlife to thrive. Erosion control and blighted view sheds are also major considerations in maintaining right-of-ways. Whitener said the view shed along the Blue Ridge Parkway, where the ground-fault reportedly took place, is particularly sensitive given its importance to tourism and efforts taken to preserve its natural beauty. “Blue Ridge Electric and parkway officials are working on an agreement to trim any trees in the affected area that might jeopardize power reliability again,” Whitener said.