Wiring Methods in Hazardous Locations:

[rattus]

I was taught that the object is to contain an explosion within the conduit and within the glass shields over the light bulbs without setting off a fire or explosion on the outside. Has the approach changed?

[rbalex]

If you also include enclosures other than conduits it’s still the dominant protection technique (explosionproof) in Class I, Division 1.

There are several other recognized Class I techniques. (500.7 for “Divisions” and 505.8 for “Zones”) A few, such as purging or intrinsic safety, are also recognized Class I, Division 1.