Electrical Area Classification - Basement

[scrub12]

I have an industrial facility that performs dispensing, filling, and process of flammable materials with flashpoints less than 100°F. The building has three floors with a basement. The question is - does the basement need to be considered electrically classified assuming there are no openings to the classified area above?

 

[rbalex]

Without knowing the details of the installation and the processes involved, the quick answer is yes, it will be Class l, Division 1. There are too many considerations beyond, “…there are no openings to the classified area above.”

 

[scrub12]

Thank You! There is an electrical room in the basement beneath the process area on the first floor. The first floor has areas considered Class I, Division 1, and 2. Even if there are no stairways, or openings up to the first floor (access is from a ramp outside) it is still considered division 1 since it is below grade. I can't find a clear reference for this in NFPA 30 other than flammable materials shall not be stored or used in basements.

 

[scrub12]

Thank You! There is an electrical room in the basement beneath the process area on the first floor. The first floor has areas considered Class I, Division 1, and 2. Even if there are no stairways, or openings up to the first floor (access is from a ramp outside) it is still considered division 1 since it is below grade. I can't find a clear reference for this in NFPA 30 other than flammable materials shall not be stored or used in basements.

Specifically NFPA 30 - 7.3.4 – A classified area shall not extend beyond a floor, wall, roof, or other solid partition that has no opening within the classified area.

 

[rbalex]

I suspect there are raceways between the basement electrical room and the floors above. See NEC Section 501.15 Informational Note No.1. :

Seals are provided in conduit and cable systems to minimize [not prevent] the passage of gases and vapors…

Especially when dealing with heavier than air gases/vapors, it is almost certain that they will be transmitted through the raceways to an open space below the floor.

NFPA 30 is a very good standard, but it is not quite adequate for the good engineering guidance provided by NFPA 497. Look at its Chapter 5, particularly Section 5.9 for the procedures to establish proper electrical area classifications.

Edit add: I should add this does not necessarily mean the room must be Division 1, but so far, there has not been given enough detail that it shouldn’t be.

 

[scrub12]

Specifically NFPA 30 - 7.3.4 – A classified area shall not extend beyond a floor, wall, roof, or other solid partition that has no opening withig the classified area.

I suspect there are raceways between the basement electrical room and the floors above. See NEC Section 501.15 Informational Note No.1. :

Especially when dealing with heavier than air gases/vapors, it is almost certain that they will be transmitted through the raceways to an open space below the floor.

NFPA 30 is a very good standard, but it is not quite adequate for the good engineering guidance provided by NFPA 497. Look at its Chapter 5, particularly Section 5.9 for the procedures to establish proper electrical area classifications.

Edit add: I should add this does not necessarily mean the room must be Division 1, but so far, there has not been given enough detail that it shouldn’t be.

Thank you very much for the helpful quick reply today. This makes sense especially with being below grade.