class 1 division 2 boundaries
- Thread starter deec
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- Mission Viejo, CA
- Occupation
- Professional Electrical Engineer
That's an excellent question and, to my knowledge, there is no documented standard that covers it. I can only offer my opinion.
A boundary is created relative to a potential gas or vapor source, and a physical barrier creates a "boundary" with respect to the source. Conceptually, the desire is for a boundary seal to minimize the migration of vapors and gases through a conduit from one location to another, so it is desirable to seal it where it penetrates a physical barrier. However, where the two locations are at the same relative air pressure, it is not generally necessary to use an explosionproof seal.
Now, if Section 513.8 is what is under discussion, the wall is irrelevant since the slab's surface is what creates the boundary and underground wiring must comply with either 513.8 (A) or (B).
A boundary is created relative to a potential gas or vapor source, and a physical barrier creates a "boundary" with respect to the source. Conceptually, the desire is for a boundary seal to minimize the migration of vapors and gases through a conduit from one location to another, so it is desirable to seal it where it penetrates a physical barrier. However, where the two locations are at the same relative air pressure, it is not generally necessary to use an explosionproof seal.
Now, if Section 513.8 is what is under discussion, the wall is irrelevant since the slab's surface is what creates the boundary and underground wiring must comply with either 513.8 (A) or (B).
- Location
- Mission Viejo, CA
- Occupation
- Professional Electrical Engineer
After rereading it, I note my previous post is with respect to Class I, Division 2 locations only.
Strathead
Senior Member
- Location
- Ocala, Florida, USA
- Occupation
- Electrician/Estimator/Project Manager/Superintendent
Rob, I felt the question and the answer were not in synch. At least, after the OP asked the question it raised one in my head. Basically is the space between the two sides of sheetrock a classified area with classified area on both sides? My first thought was yes, but then I thought if only one side was classified, then no. So my final answer is, I don't have a clue.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
I think that is the right answer.
Might vary from one jurisdiction to another to some extent. I think will at very least depend on what kind of finish is applied to the wall, and even if there is any openings in that wall, primarily doors or windows and how they are designed/arranged/maintained. Then there may be differences in division 1 vs division 2 as well as effects from any ventilation that may apply to an area. I guess OP says he has div 2 location and presumably unclassified on the other side of the wall.
Strathead
Senior Member
- Location
- Ocala, Florida, USA
- Occupation
- Electrician/Estimator/Project Manager/Superintendent
I think that is the right answer.
I guess OP says he has div 2 location and presumably unclassified on the other side of the wall.
I think he was implying div 2 on each side of the wall and whether they are considered the same area or two separate areas with a boundary between.
- Location
- Mission Viejo, CA
- Occupation
- Professional Electrical Engineer
As I mentioned in my earliest response neither the NEC nor any other standard I know of deals specifically with two locations, while having the same "classification", are actually classified because of different sources or parameters. My opinion, that a physical barrier creates a 'boundary' with respect to Section 501.15(B)(2) and dealing with a conduit that crosses such a boundary, is based on my experience, my interpretation of Section 501.15 IN No.1, and how I would deal with the issue should it arise in a practical case.
I also responded to "slabbing" mentioned in the OP which is the basic "hanger" issue of Section 513.8.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
I see what you are saying now and I think he is asking if the space inside the dividing wall would be a classified area.
My bet is many AHJ's will say yes, especially if there is classified area on each side, all depends on how well it is "suitably cut off from the hangar" as is mentioned in 513.3(B).
If you wanted to bring say a PVC raceway out of the slab, here in the past it likely would be acceptable to encase it in 2 inches of concrete until you get above 18" (as long as you don't end up in other classified area above that 18").
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