Class II Div 2 Equipment

[mls1]

We are struggling to find specific requirements for equipment that must be installed in a Class II Division 2 Group F location. From the NEC description it would appear that NEMA 12 is sufficient but that doesn't give us a lot of confidence that we're 100% covered. Is there any clear guidance out there for specific equipment ratings and installation practices required for Class II Division 2?

 

[rbalex]

I am assuming you have read NEC Section 502.10(B) carefully. Subsections 502.10(B)(1),(2),and(3) cover acceptable wiring methods. Subsection 502.10(B)(4) specifically states that enclosures shall be dusttight. If you read the Notes to Table 110.28, you will discover that there are several acceptable enclosure-types beyond Type 12 that are suitable for Class II, Division 2.

 

[mls1]

rablex - We appreciate your response. Yes, we've reviewed 502 carefully but 110.28 does not provide as much clarity as one might hope. The NEC text (not the handbook text) explicitly states that the types outlined in 110.28 are for "other than hazardous (classified) locations." Hence our confusion as to what markings would qualify for the requirements outlined in 502. The handbook notes do reference UL types that would be suitable for "Dusttight" but handbook notes are not code. It certainly is better than nothing but not quite as satisfying as an explicit rating.

 

[rbalex]

For what it's worth, Type 12 isn't for hazardous locations either. In fact, Table 110.28 identifies it as an indoor enclosure. Throughout Articles 500 to 503, various General Purpose (UL calls them "Ordinary Location" as opposed to "Hazardous Location") enclosures are recognized as suitable [Section 500.8(A)] for many Division 2 locations. Section 502.10(B)(4) tells you dusttight is acceptable in Class II, Division 2. See Section 502.115(B) for example. There are several other examples in Article 502, Part III, Beginning in Section 502.100.

 

[mls1]

Thanks again. We appreciate your knowledge of the code. Looks like 500.8(B)(3) gives us what we needed:

"Where specifically permitted in Articles 501 through 503, general-purpose equipment or equipment in general-purpose enclosures shall be permitted to be installed in Division 2 locations if the equipment does not constitute a source of ignition under normal conditions"

If we interpret the use of "dusttight or otherwise identified for the location" as implying general-purpose or specifically listed then dusttight per 110.28 is suitable and need not have any additional markings beyond its type rating.