class 2 barrier wall

[Brent Schaffer]

I am setting a 1600A 480v MCC in a Class2 Div2 GroupG location. I want to put a wall up that will separate the MCC from the Class 2 room so I can keep the MCC NEMA 1. Where do I find what the wall requirements are?

I am located in an area that I have no authority of jurisdiction so I am not sure where to get the information.

 

[rbalex]

From NFPA 499 Section 5.3.6.1:

Walls are much more important in separating Division 1 areas from Division 2 and unclassified areas in Class II areas than in Class I areas. Only unpierced solid walls make satisfactory barriers in Class I areas, while closed doors, lightweight partitions, or even partial partitions could make satisfactory walls between Class II, Division 1 areas and unclassified areas. Area classification does not extend beyond the wall, provided it is effective in preventing the passage of dust in suspension or layer form.

The first sentence is poorly written and can be misleading if not read carefully IMO, but it is simply making a practical comparison between Class II and Class I classification applications. The second sentence clarifies and expands the comparison.

 

[weressl]

I am setting a 1600A 480v MCC in a Class2 Div2 GroupG location. I want to put a wall up that will separate the MCC from the Class 2 room so I can keep the MCC NEMA 1. Where do I find what the wall requirements are?

I am located in an area that I have no authority of jurisdiction so I am not sure where to get the information.

In addition to Bob's comment I suggest that you may also/or want to consider keeping the non-classified area under a positive pressure in relation to the classified area.