NEC (2020) 516.5(D)(1) Unenclosed Spray Process

Exactly What Is An "Unenclosed Spray"? The wording is a bit confusing to me - - wiring & equipment located outside, but within 20-Ft Horz and 10-Ft Vert of an enclosed spray area and not separated from the spray area by partitions - -

Example: An 40-Ft Hi-Bay, 100 -Ft Wide, 400-Ft Long Steel Building. Customers sets up an area, say 50-Ft by 50-Ft area, to spray paint some finished product at one end of the structure. So the 50x50x10-High area is the "Spray Area", and since it is open to the remainder of the space, then the 20-Ft Horz. zone just outside the 50x50 area, on each side, and (10-Ft above the 10-High) is the "Classified Area"? All areas beyond the 20-Ft boundaries are "unclassified"?

Please let me know your interpretation - -
 

rbalex

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Sorry for the late reply. I tried to do a little research on enclosed as it applied to the question. It is defined in Article 100 but doesn't seem to apply as used in Section 516.5(D)(1). I then reviewed NFPA 33 Part 6.5.1 because it is where the original content was extracted as indicated by the [33:6.5.1]. (See Section 516.1 IN No 2.)
It reads:
Electrical wiring and utilization equipment located outside but within 6100 mm (20 ft) horizontally and 3050 mm (10 ft) vertically of an unenclosed spray area and not separated from the spray area by partitions extending to the boundaries of the area designated as Division 2, Zone 2 or Zone 22 in Figure 6.5.1 shall be suitable for Class I, Division 2; Class I, Zone 2; Class II, Division 2; or Zone 22 locations, whichever is applicable.
rbalex note: I added the above text to the quote to indicate where the error occurred.

It would seem there was an error transferring the original text from NFPA 33. NFPA 33 Figure 6.5.1 is virtually identical to NEC Figure 516.5(D)(1).
 
Looking on the NFPA web-site, I see no Amendments, nor Errata for this article. So it does appear to me this is addressing "Spray Processes" that can take place inside a large building structure (i.e.-enclosed), but not in a "Spray Booth" or similar. There is the "Designated Spray Area" (what ever length, width & heigth it may be) that is Class-1, Div1 (or equivalent) then 20-Ft out & 10-Ft above that "Spray Area" is Class-1, Div-2 (Or equivalent).
2020 NEC Figure 516.5(D)(1) would be clearer if they showed another boundry that represented the "Enclosed Area"(i.e. building or structure).
 

rbalex

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I won't do it for you, but I suggest you contact the NFPA Standards Council (SC) and let them clarify/correct the issue. Figure 516.5(D)(1) was extracted from NFPA 33, Figure 6.5.1 and, since Article 516 must use the referenced Standard as its basis, only the SC can fix it at this time because it is an inter-Technical Committee issue. Most likely, the SC would just direct the NEC Technical Correlating Committee (TCC) to issue an Errata.

If you wish, you may submit a Public Input for the 2023 NEC or to the 2021 NFPA 33 Edition if you want another boundary indicated in the Figure.
 
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