PORTLAND, Maine — City Electrician Dan McMahan isn’t afraid of heights. Or if he is, he hides it well. On Monday morning, McMahan stood atop a small platform six-or-so stories above Hadlock Field, where the Sea Dogs play. Unphased by the distance between himself and the ground, McMahan was busy cleaning lenses and screwing in basketball-sized light bulbs. The lights are part of a nearly 300,000-watt system illuminating evening baseball games for the Sea Dogs and stadium mates Portland High School.