After 15 years as the town’s electric utility director, Coleen O’Brien resigned effective last Friday to accept the job of general manager of the Reading Municipal Light Department. O’Brien worked for the Danvers Electric Division for 18 years overall, the first three as director of engineering and operations, and the remainder as electric utility director, according to Town Manager Wayne P. Marquis. “She was an exceptional employee and did an excellent job,” he said. “She leaves behind a solid team of employees, and a very reliable electrical system.” The new job marks “a good career opportunity for O’Brien,” Marquis said. He noted that Reading’s municipal light department, which serves North Reading, Wilmington, and Lynnfield, in addition to Reading, has twice as many customers as the Danvers division. Marquis said the town plans a full-scale recruitment process to select O’Brien’s replacement with the expectation of hiring someone by early fall. An interim director was expected to be named.