Cl. I, Div. 1 labeled fixtures maybe factory sealed and do not require sealing in the field. The fixture would be so marked. In some applications wherte you need large wattage fixture, 250W or higher, you may be forced to use Division 1 rated fixture because of the T-rating. If this fixture does NOT indicate that it is factory sealed it woould require an external XP seal in both Div. 1 and 2.I have a install with 6 HID fixtures that are not factory sealed. Do I need to seal off every fixture or just at the boundary?