The ceiling box is a CANTEX EZ18CN. I have used them quite often in the past. Probably won't anymore after this. The box is rated @ 50#. I always discard the cheap Chinese 8-32's that come with the fixtures and replace them with better quality 8-32's. At first I thought it had to be Rotozip damage but there is no evidence of that. The house is 1 1/2 years old. There have been 3 separate incidents of dangling fixtures over the course of 6 months. Lamp wattage is correct. Any thoughts?