Can a UL type 4 enclosure be used in a Class II, Division 2 location?
The enclosure would contain a PLC and motor starters also any local motor disconnect switch.
UL type 4 and NEMA type 4 enclosure are intended to prevent environmental factors (water, Ice) from entering the enclosure.
Class II Div II enclosures are intended to prevent environmental factor inside in the enclosure from reaching combustible dust atmospheres on or outside the enclosure.
I have seen the AHJ approve Type 4 enclosures in Class II Div II locations but only where the is no switching involved inside the enclosure. ( terminal and barrier strips)
Really, it all goes back to the enclosure approvals and listing. Check with the enclosure manufacturer and ask if the enclosure you are looking at is approved for the location.
For Class II, Division 2 areas, in the 2014 edition of NFPA 70, article 502.10(B)(4), it states that all Boxes and Fittings shall be “Dusttight.” It does not require the box to be “listed” for the classified location (as you would find in Article 502.10(A)(3) (Class II, Division 1 locations).
As far as I can tell, though I am not an authority on these things, you should be allowed to use it, as long as it is, Dusttight.
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