About 500 NV Energy customers were without power for more than nine hours today after four circuits at the Round Hill Substation failed at 5:30 a.m. About 5,000 customers living from Stateline to Cave Rock and up Kingsbury lost power initially."Crews were able to restore service to about 2,500 customers, primarily in the Round Hill-Zephyr Cove area, at 9 a.m.," he said. "There were brief outages, 15 minutes or so, affecting downtown Stateline and the Nevada side of Heavenly Mountain, but those customers were back in service."It took crews about four hours to restore power to all but 500 customers. …