National Electrical Code Articles and Information

National Electrical Code Top Ten Tips: Article 516 -- Spray Application, Dipping, and Coating Processes

1. Article 516 covers the regular (as in time, not as in "normal") or frequent application of liquids or powders that may burn [516.1]. These include such operations and enamel powdering, spray painting, and varnish dipping.
    
2. In the 2017 revision, Article 516 differentiated between a spray room, spray booth, and spray area. Other types of areas were also described in 516.2. With the 2020 revision, 516.2 was removed. Normally when this happens, you look in Article 100. But these difinitions do not appear there, they are just gone. In the index of the 2020 Code, if you look up "spray applications" it will tell you definitions are in Article 100. The CMP felt it wasn't necessary or helpful to define these terms. If you read through Article 516 requirements, you can understand why they reached that conclusion. With the 2023 revision, all definitons were moved to Article 100. 516.2 came back as "Other Articles". This refers to a small table, and all of the referenced articles are in Chapter 5.
    
3. For a ventilated area for certain fuctional types of containers (e.g., supply containers, waste containers, etc.) holding a Class I liquid, you must classify the location [516.4]. This is your first task in applying Article 516. After you determine the classification, you will then need to conform to the applicable requirements that follow from 516.5 onward. Now just to avoid confusion, it's not the electrician who does the area classification. You get that information from the property owner or the representative of the property owner.
    
4. The requirements for this can seem mind-numbing, and you have five types of area to consider [516.4]. But Figure 516.4 makes this task much easier than it otherwise would be.
    
5. Use Figure 516.5(D)(1) if you're working with unenclosed spray processes.
    
6. Use Figures 516.5(D)(2) if you're working with enclosed spray rooms or booths that are closed-top, open-face, or open front spray.
    
7. If equipment is within a Class I location (containing vapor only, not residues), apply 516.6.
    
8. If equipment is not within a classified location, apply 516.7. This section was heavily revised with the 2023 revision. The 2020 revision was confusing and contested, the 2023 revision is abundantly clear.
    
9. Read through 516.10 to see if any of the equipment you're working with is considered "special equipment." With the 2023 revision, transformers have been removed from this section.
    
10. In Article 516, you will find references to "grounding" (i.e., 516.10(A)(6) and 516.16]. This is incorrect. What it is actually referring to is bonding. You can see this if you read the definitions of grounding and bonding in Article 100 and then read the actual requirements provided in 516.10 and 516.16. In fact, you should not ground anything in these systems. Bond it, only. See Article 250, Part IV. That said, we see in 516.23(4) a requirement to bond scaffolding to the workpiece and ground it by an approved method. What is probably meant here is to connect it to the equipment grounding conductor (EGC), which is actually an equipment bonding conductor. The only ground connection should be on the primary side of a service or separately derived source. Because the EGC ultimately terminates to that connection rather than just tying load side equipment together, it is called a grounding conductor. But if you were to skip the EGC and tie directly to ground, you would find equipment to be at different levels of potential and you'd find undesired current flowing between metallic objects. That is not what you want to happen when you have volatile chemicals present.