Class 2 Division 1&2 Lighting

I recently went on a lighting job at a grain mill that was not audited by myself or my company. The auditor ordered T8 Flourescent High Bay FIxtures for the grain mill and the warehouse. I promply sent the job back for reaudit because these fixtures where not rated for this location. My question is that can a vapor tight fixture be installed in the warehouse portion where there is no milling taking place if they are installed correctly and dust proof? I am currently trying to find a cut sheet that gives the listing of one that is class 2 division 2.

Thank You,
Devin
 
I am pretty much 100% positive. The Grain Mill Portion is classified as Class II Division I and The Warehouse is Considered Class II Division II. I spoke both with my inspector and an engineer today and they agreed. My inspector said he would pass vapor tights in the warehouse as well but this is New York so I figured I would get the opinions of the updated world LOL.
 

rbalex

Moderator
Staff member
Squnsel’s question is on point and I agree the locations, especially the warehouse, are likely to be over classified. However,your post doesn’t indicate who determined the classifications and your question is still valid.

For Class II, Division 1, Group G: The luminaires must be identified for Class II. “Vaportight” is meaningless for this purpose. In order to be identified, it must either be listed for the specific Group G location, or be specifically marked “Dust-ignitionproof” and marked with a Temperature Code per Section 500.8(D)(2). [See Sections 502.130(A)(1) and 500.8(B)(1)]

Class II, Division 2,Group G: While a vaportight luminaire would intuitively be dusttight, it is irrelavent. It is imperative that it either be a recognized NEMA dusttight design (3, 3S, 3SX, 3X, 5,12, 12K, and 13) or marked “dusttight” to meet the requirements of Section 502.130(B)(1). More important is “Each fixture shall be clearly marked to indicate the maximum wattage of the lamp that shall be permitted without exceeding an exposed surface temperature in accordance with 500.8(D)(2) under normal conditions of use.” The luminaire does not necessarily need to be specifically marked for Class II, Division 2.
 
Thank you for your feed back it is much appreciated I did review all of the code section that you have mentioned in your thread. However I was not considering placing the Vapor Tights in the mill area that I considered Class II Division One.

My question for you is why would you consider these areas over classified and do you consider the code to be over classifing or my estimation?

Last year in my area a firefighter was killed in a grain silo explosion that was started by an electrical fire in an adjoining building. I think I would rather error on the side of caution in this area.
 

rbalex

Moderator
Staff member
The NEC is primarily an installation document. Except for locations covered by Articles 511 through 516, the NEC is inadequate for accurately determining electrical area classifications. If you intend to do proper electrical classification [See Section 500.4(A)] of Class II locations on your own, you must become familiar with NFPA 499. [See NEC Section 500.5(B), FPN No. 2]

Do NOT just look at NFPA 499, Section 5.8 Classification Diagrams. You must become familiar with all the preceding text as well. It really isn’t that difficult, but it is essential to properly understand the explosion/fire characteristics of Class II materials to properly classify a location. You might even be surprised to discover what it actually takes to be a combustible dust.
 

don_resqcapt19

Moderator
Staff member
... However I was not considering placing the Vapor Tights in the mill area that I considered Class II Division One.
...
A vapor tight fixture is not suitable for a Class II, Division 2 area unless it has markings to say that it is. Even a fixture marked for Class 1, Division 1 cannot be used in a Class II area unless it is also marked for Class II.
 
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