NEC Code Issue - Unclassified area opening into Div. 2 Area

[sabotage]

I have an area that is classified as a Division 2 area, and there is a Unclassified stairwell that opens into this area. Is there anything in the NEC code that forbids this? Or do I need to put an airlock or some other type of seal between these two areas. Any help would be appreciated.

 

[JLSeagull]

I am not sure that I understand the question. Classified areas and unclassified areas are adjacent everywhere. Move 50-foot outside an open process unit and move into an unclassified area. Electrically the issues consider seals etc. for conduit running between the areas.

 

[sabotage]

I guess my question is, do classified areas need to be fully sealed from unclassified areas, and if they do, does it depend on the type of facility or what Class it is?

For example, in the 1999 NEC Code, 511-3 (d) states that "Areas adjacent to defined locations in which flammable vapors are not likely to be released, such as stock rooms, switchboard rooms, and other similar locations, shall not be classified where mechanically ventilated at a rate of four or more air changes per hour or where effectively cut off by walls or partitions." So it seems that depending on the situation, a classified area and an unclassified area is able to exist next to each other.

However, in Table 515-2, for a "Office and Rest Rooms" location, it states in Extent of Classification that "If there is any opening to these rooms within the extent of an indoor classified location, the room shall be classified the same as if the wall, curb, or partition did not exist." Assuming a door is an opening, then if the door opened to a Division 2 area, then the Office/Rest Room would also be classified as a Division 2 area, which means that there are no unclassified areas, unless they are fully sealed.

However, 511 is for Commercial Garages, Repair and Storage, while 515 is for Bulk Storage Plants, so that could explain the difference.

My question is whether or not I need to fully seal an adjacent Division 2 area from an Unclassified area, and if it depends on the facility type.

I hope I have cleared up any confusion, if more clarification is needed I can provide it.

 

[rbalex]

LOL - if you had asked your question this way on the other BB it would have been much easier to answer: NO - no physical barrier is needed between a Division 2 location and an unclassified location. You have to draw the line somewhere.

As a matter of fact, no physical barrier is necessary between a Division 1 and Division 2 location either.

 

[rbalex]

I should note this applies only to the classification of the location. We are not talking about seals required in the wiring methods.

 

[sabotage]

haha Thank you again. I wasnt getting any responses on this one so I thought I was wording it wrong.