I am in a power house running conduit from a non hazardous room through a block wall into a hazardous coal dust location, i ran 30' of conduit to an explosion proof motor, i have a seal off and a 2' piece of explosion proof seal tight. where does the seal off go?? thanks.
Class II locations don't need a seal off.
You are not trying to contain an explosion if one should happen like you are doing for class I locations.
Difference is you are dealing with a dust and not a vapor. Vapor can still find its way into the raceway, motor, or other enclosure, dust is not as sneaky.
You do need a seal where you leave the classified area but this can simply be simple duct seal in the end of raceway in the first enclosure outside the classified area.
Your motor didn't necessarily need to be explosion proof - just rated for division II, and your flex could have been liquidtight flexible metal conduit as far as I know.