National Electrical Code Top Ten Tips:
Article 516 -- Spray Application, Dipping, and Coating Processes
- 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.
- 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.
- 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.
- 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.
- Use Figures 516.5(D)(1) and (2) if you're working with unenclosed spray areas.
- Use Figures 516.5(D)(4) if you're working with enclosed spray areas.
- If equipment is within a Class I location (containing vapor only, not residues), apply 516.6.
- If equipment is not within a Class I location (or a Class II),
apply 516.7. Make sure, for example, any wiring above a Class I or Class II location is in one of the raceway types listed there. Nonmetallic tubing is listed, but metallic tubing (aka, EMT) is not explicitly listed. However, "metallic raceway" is in the list so necessarily EMT is a raceway type you can use in such an application.
- Read through 516.10 to see if any of the equipment you're
working with is considered "special equipment." For example, transformers are considered "special equipment [516.10(1)]; be sure to locate a transfomer outside the Class I location unless you use a transformer that is identified for use in a Class I location.
- 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 currentf flowing between metallic objects. That is not what you want to happen when you have volatile chemicals present.