Adjacent to Class I Division I

[StephWri]

I am unsure how to determine what "adjacent" means when refering to a Class I hazardous area. I am reviewing some old building prints which define the area withing 12' of the floor as Class I Division I. Does that mean that the rest of the room above 12' is Division II. I also have a Div I area next to a warehouse separated by a wall with large equipment passages. Is the warehouse Div II? Are there some metrics I can apply to make a better determination?

 

[stookeyfpe]

Are you dealing with flammable liquids or gases. If so, the Division 1 boundary, simply stated, is where vapor will be present. The Division 2 boundary is adjacent to the Division 1 boundary.

In the case of the warehouse, the area around and near the openings would most likely be assigned a Division 2 area classification.

See Article 501 of the National Electrical Code and NFPA 497 for guidance on area classification.