class 1 div 1 & class 1 div 2-locations

[jflynn]

We are currently wiring a facility that has been classified by the engineer as class 1 div and class 1 div areas.

i have a couple of questions: on the general construction methods of the areas-the walls are 2-layer sheetrock-and the ceiling is an acoustical 2x4 standard everyday lay in tiles.All the electrical is called to be rated for the areas installed-i just have never seen a class 1 div 1 area-with an acoustical ceiling and sheet rock walls.?

We asked the GC how the construction complies-and was told due to the location of the potential gases( height off the floor?)-that above the acoustical ceiling was actually not classified-the areas do have at least 4-air exchanges an hour-minimum


The light fixtures are mounted tight to the ceiling which is about 9' AFG.-does the wiring method above the ceiling need to class 1 div 1 rated.?

There are 2-rooms that are separated by only a sheet rock soffit:-1-ceiling higher than the other-the high ceiling has class 1 div 2 lay in troffer type fixtures-you can walk between both rooms there is no wall separation.

we do not do alot of this type of work-so we are a little confused on how the classifactions were derived.
thank you

 

[rbalex]

Unfortunately, Section 500.4(A) only requires proper documentation NOT proper classification. Without knowing the ALL the specific topography, ventilation, operating processes and activities involved, there's no way to for anyone here to accurately classify the installation you have described. However if anyone says that a location isn't "actually" classified, it hasn't been properly documented.

Once a location has be classified and documented, the electrical installation must go "the whole nine yards" whether it needs to or not. Unless the documentation specifically identifies that the luminaires are located out of the classified location they must be suitable for the identified classification as documented.

While the selection and installation of building materials and mechanical equipment may affect the electrical area classification, they aren't directly in the scope of the NEC.

 

[jtinge]

We are currently wiring a facility that has been classified by the engineer as class 1 div and class 1 div areas.

we do not do alot of this type of work-so we are a little confused on how the classifactions were derived.
thank you

I don't know what your engineer used to develop the hazardous location classifications for your project, but we typically start with NFPA 497, Recommended Practice for the Classification of Flammable Liquids, Gases, or Vapors and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas.

Depending upon the process, other codes and standards may be applicable, but NFPA 497 is usually a good place to start.

Once the classifications are determined, we document them on a facility map which then is used to determine the type and extent of hazardous location wiring methods per the NEC.

We will typically determine what methods we want to be used and include them in project specs and drawings rather than leaving it to the EC to decide. That way the proposed design can be verified for compliance with code requirements prior to letting the contract. The verified design is then used to verify and document the as-built system for design and code compliance prior to commissioning.

 

[jflynn]

Unfortunately, Section 500.4(A) only requires proper documentation NOT proper classification. Without knowing the ALL the specific topography, ventilation, operating processes and activities involved, there's no way to for anyone here to accurately classify the installation you have described. However if anyone says that a location isn't "actually" classified, it hasn't been properly documented.

Once a location has be classified and documented, the electrical installation must go "the whole nine yards" whether it needs to or not. Unless the documentation specifically identifies that the luminaires are located out of the classified location they must be suitable for the identified classification as documented.

While the selection and installation of building materials and mechanical equipment may affect the electrical area classification, they aren't directly in the scope of the NEC.

understood the luminaires are class 1 div 1-rated,as you mention if we install the systems as "the whole nine yards" then we are covered.thank you