I'm waiting to hear back from my local inspector about doing a camera install in a Class 3 Div 1 area myself. I would think an explosion proof housing would be acceptable, but when indoubt, contact the local inspector. After all he, or she, is going to be the one inspecting it anyways.
IPVMU Certified | 12/19/13 02:25am
Class 1 Div 1 is the most stringent rating required, and simply installing a standard IP camera in a rated housing likely is not sufficient. The chamber the camera is located in (the housing) and all cabling trailing from the camera need to be rated as an assembly.
We cover a few Class 1/Div 1 options in our Hazardous Area Surveillance note. A vendor like IVCCO has Class 1/Div1 options, but don't expect anything inexpensive or remarkable in terms of camera performance. Indeed, the high relative cost ($5000+ USD) comes from the cost of certifying the assembly.