I am in the process of renovating a standard room constructed of CMU walls to an alcohol storage room (ethanol). All existing devices are to be replaced with Class 1, Division 2 devices. If a device (receptacles or light switches) that is flush mounted in the CMU wall is either replaced or removed entirely and the circuit is to remain in use, what is the best procedure to seal that box location in order to maintain a Class 1 hadardous location?
Class1, Division 2
- Thread starter James539
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- Status
- Location
- Mission Viejo, CA
- Occupation
- Professional Electrical Engineer
Re: Class1, Division 2
I?ll have to confess my ignorance, and admit I have don?t know what the acronym CMU means. I can make a few observations though.
1.) Depending on the operation, ventilation, quantities of product involved and sizes and types of containers, if the room is used simply as storage, it still may not need to be classified at all.
2.) If classification is truly required, if devices are simply removed and the circuits are then recovered by simple splicing, the enclosures will not need to be sealed in a Division 2 location. However that only moves your sealing problem to the boundary. See 501.15(B)(2) in the 2005 NEC.
When I get a better understanding of the construction, I may be able to assist with the sealing of enclosures that are required to be.
I?ll have to confess my ignorance, and admit I have don?t know what the acronym CMU means. I can make a few observations though.
1.) Depending on the operation, ventilation, quantities of product involved and sizes and types of containers, if the room is used simply as storage, it still may not need to be classified at all.
2.) If classification is truly required, if devices are simply removed and the circuits are then recovered by simple splicing, the enclosures will not need to be sealed in a Division 2 location. However that only moves your sealing problem to the boundary. See 501.15(B)(2) in the 2005 NEC.
When I get a better understanding of the construction, I may be able to assist with the sealing of enclosures that are required to be.
- Location
- Illinois
- Occupation
- retired electrician
Re: Class1, Division 2
CMU= cement masonry unit (concrete block)
CMU= cement masonry unit (concrete block)
- Location
- Mission Viejo, CA
- Occupation
- Professional Electrical Engineer
Re: Class1, Division 2
I apologize for delaying my response so long after Don clarified the acronym.
My original comments still generally stand, but I may be able to temper the second one a bit.
Section 500.4(A) requires the electrical area classification be documented. Since you have to ?draw the line? somewhere and it is only Division 2, I suggest it be the interior of the walls. That would place most of the raceway system outside the classified area.
In those cases, where no arc-making device remains, any otherwise acceptable conduit body or box would be acceptable. They should be covered with a removable plate so they remain ?Accessible (as applied to wiring methods)? yet maintaining the arbitrary ?documented? area classification boundary. Any future work that may be necessary on them should be done under a ?hot-work? permit.
Where it is necessary to retain an arc-making device, such as a switch or receptacle, the solution is a bit more complex; however, it is still fairly straight-forward. Several manufactures make devices that are ?factory-sealed? and fit in or on otherwise non-explosionproof boxes. Since CMP 14 has fundamentally removed the requirement that ?boundary? seals be explosionproof, this setup would provide the safety necessary AND remove the need for other seals in the raceway system since the boundary is now the wall. The ?hot-work? permit consept applies here too.
I apologize for delaying my response so long after Don clarified the acronym.
My original comments still generally stand, but I may be able to temper the second one a bit.
Section 500.4(A) requires the electrical area classification be documented. Since you have to ?draw the line? somewhere and it is only Division 2, I suggest it be the interior of the walls. That would place most of the raceway system outside the classified area.
In those cases, where no arc-making device remains, any otherwise acceptable conduit body or box would be acceptable. They should be covered with a removable plate so they remain ?Accessible (as applied to wiring methods)? yet maintaining the arbitrary ?documented? area classification boundary. Any future work that may be necessary on them should be done under a ?hot-work? permit.
Where it is necessary to retain an arc-making device, such as a switch or receptacle, the solution is a bit more complex; however, it is still fairly straight-forward. Several manufactures make devices that are ?factory-sealed? and fit in or on otherwise non-explosionproof boxes. Since CMP 14 has fundamentally removed the requirement that ?boundary? seals be explosionproof, this setup would provide the safety necessary AND remove the need for other seals in the raceway system since the boundary is now the wall. The ?hot-work? permit consept applies here too.
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