We recently installed new electrical boxes and hung fans from them. We caulked around the boxes to seal off airflow into the attic. There are several small holes (and one has a medium sized hole) on the boxes. What's the proper way to seal this off to prevent the blown-in insulation from falling through the hole into the box (a fire hazard I presume)? Is caulking them appropriate or just putting a piece of electrical tape over the holes?