Thank you. I am aware of table 310.13. We are having several issues, though. The lamps keep failing. Refrigeration technicians have relamped, replaced the ballast, the tombstones, and in some cases, rewired. The bulbs are still failing within 1 day to 2 weeks. These lights are cycled 16 hours on/8 off. Any ideas on why the bulbs keep failing? Are there special ballasts we should be using?