Spray Room

[Hoyt]

We have a small "Finishing room" in a High School enclosed by walls and ceiling, apparently they will be doing some spraying in this room......

Per N.E.C. 516.3(b)(1) it appears as if the entire room is Classified. Per this it seems as if I will need explosion proof light fixtures. Anyone see anything that does not require these type of light fixtures? Possibly due to small quantities of Flammable liquids and vapors? Above a classified area?

We currently have standard Vapor tight fixtures but they are not Class and Division Rated. Just IP65.

I did post this in Hazardous Forum but am not sure how much viewing that one gets.

 

[Hoyt]

Sorry Wrong spot for this tread. Disregard

 

[Dennis Alwon]

From the little I know I would agree that vapor tight is needed.

 

[rbalex]

Actually, what you read in 516.3(B)(1) is that it is Class I, Division 1. Vaportight alone is not adequate. See Section 501.130(A)

 

[kwired]

I would let someone else classify the area since it is not all that obvious just what the classification is. Like the owners insurance company, fire marshal or both. Once the classification is established then you know what you have to do based on chapter 5 of NEC. Outside of that treat it as worst case scenario and call it CL1 D1. The trouble could be defining where the boundaries of the area are, and what is classification of adjacent areas.

 

[rbalex]

Section 516.3(B)(1) makes the boundaries pretty clear. I've said before, outside Arts 511 through 516, it's pretty hard to properly classifiy an area from the NEC alone. However, if the installation is as clearly within the scope of Art 516 as it appears in the OP, classification is usually straight forward.

 

[sgunsel]

Is it a "spray room" or is it a room that will contain a spray booth or an open spray area? Caution is required in any event, especially in an educational setting.

NEC Article 516 is derived from NFPA 33. The 2008 NEC referenced the 2007 edition of NFPA 33, and the 2011 NEC references the 2011 edition of NFPA 33 (with some errors). NFPA 33, Chapter 6 identifies the electrical classification areas for various types of spray operations and addresses lighting. The 2011 edition of NFPA 33 is actually more liberal with some area classifications than previous editions.

NFPA 33, Standard for Spray Application Using Flammable or Combustible Materials, 2007 and 2011 Editions, Section 4.2: "Spray application operations and processes shall not be conducted in any building that is classified as an assembly, educational, institutional, or residential occupancy, unless they are located in a room that is separated both vertically and horizontally from all surrounding areas by construction having a fire resistance rating of not less than 2 hours. The room shall be protected by an approved automatic sprinkler system designed and installed in accordance with NFPA 13, Standard for the Installation of Sprinkler Systems."

Also be advised that the Class I, Division 1 "spray area" includes the interior of exhaust plenums and ducts.