Class 2 Div 1 concealed conduit

[al97]

I am new to hazardous classified locations. I have noticed that most classified locations have exposed conduit, but is there a nec requirement that would prevent you from concealing conduit in a class 2 div 1 area? I could see this being possible as long as all enclosures are dust-ignition proof and boundary seals are placed outside of the classified area. Additionally, all of the enclosures that are rated for this kind of space seem to allow for surface mounting only, and do not have a way to connected threaded conduit to the back. Has anyone had success in this area in the past and can provide details as to how you achieved this?

Thank you.

 

[rbalex]

most classified locations have exposed conduit, but is there a nec requirement that would prevent you from concealing conduit in a class 2 div 1 area?

No.

Check Section 502.15 for appropriate sealing methods. They apply to both Class II, Division 1 & 2. Note there are no “boundary seal” requirements.

It may seem odd, but the enclosure philosophies of Class I and II are significantly different. Even if installed properly, gases/vapors are still expected to enter explosionproof enclosures in Class I. Class II installations anticipate the exclusion of dusts if appropriately sealed; hince Section 502.5