According to 502.130(B)(2) luminaries in Class II Div2 location "shall be provided with enclosures that are dusttight or otherwise identified for the location". Few fixtures that I have looked at do not have a NEMA rating that would mean that they are dusttight and are not identified for the location but have an IP rating of IP66. The first digit 6 means that the enclosure is completely protected against dust ingress. Can I consider such light fixture dusttight according to NEC definition and hence install it in Class II Div 2 location?