As families prepare for spring and summer celebrations like graduations, weddings and Father’s Day, PSE&G is warning that Mylar balloons can be a hazard that cause power outages. It asks that party planners handle and dispose of Mylar balloons properly so they don’t drift into power lines. The utility said the balloons have caused several “noteworthy power outages,” such as one last summer when some 15,000 customers in Jersey City lost power for 45 minutes after Mylar balloons drifted into a substation. “Mylar balloons, which can stay inflated for two weeks or more, have a metallic coating tha…