Paint Area "Spray Booth" Strip Fixture. Explosionproof?

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larrybartowski

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A customer of mine has what they are calling a paint spray booth exhaust hood. It is not enclosed. It's basically a fancy table with a top (kind of like a tanning booth) where one can apply paint and it has an exhaust fan that connects to the top directly above the spray area. The paint is being applied with simple aerosol spray cans.

I installed sealed, gasketed, moisture proof fixtures and the customers safety dept is now questioning whether this is OK. Do I need to install explosion proof fixtures? :?

Any help is apprecaited.
 
It is my argument that because paint is applied with simple aerosol cans, and there is sufficient exhaust, in my opinion there is not a hazard.
 
The NEC does not differentiate, but NFPA 33, Standard for Spray Application Using Flammable or Combustible Materials does address aerosol spray operations. NFPA 33 is the source for NEC Article 516. The current edition (2011) of NFPA 33 applies, and therefore NEC Article 516, if aerosol usage in one location exceeds 1 liter per 8 hour period. If this is the case, since the unenclosed spray area is not a spray booth, the classified areas for an open spray area apply - see NEC Figure 516.3(C)(1). See 516.3(B) for the Div 1 extent.
If less than 1 liter per 8 hours is sprayed NFPA 33 does not apply and it would be pretty much up to the AHJ, but the open spray area would still be a logical choice.
 
Since sgunsel described the area classification parameters, I will point out that the installations outlined in Art 516 is one of the cases where equipment and wiring methods outside the classified location can be affected. See Section 516.7 (BTW explosionproof is not one of the likely affects)
 
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"My opinion" and "sufficient exhaust" are the core of the matter.

I recall the statement in my apprentice texts quite clearly: "It is NEVER the job of the electrician to determine area classification ..." Yet, in reality, we are often the most qualified person around.

Size DOES matter, else we would classify household oil furnaces the same way we classify airplane hangers or truck stops; that's how similar fuel oil is to jet fuel and diesel fuel.

It all comes down to defining what the zone boundaries are. Considering the 'low VOC' composition of many paints these days, that 'zone' gets smaller and smaller.
 
There are (2) 8' flurescent fixtures mounted along the top of the table/booth facing down and on either side of the exhaust vent. This was a "design build" job with no engineer and the AHJ already did his inspection with no issues. It is the customer's safety dept that is bring up the issue, and they're looking for me to have the answers.
 
Do not confuse low-VOC with no VOC. If there is a flashpoint below 100F, you have a flammable liquid. Whether the paint has 5 lbs per gallon VOC, 4.5, 4, 3.5, or 3 (depends on how low-voc is supplied/required/actually mixed for usage) makes no practical difference as the fire ignition hazard is the same. Plus the "solids" and their residues are combustible as well. Water-based, water-borne, and similar sounding concoctions have no dispensation either, as they typically fall into one of the above categories and are usually little more than solvent containing paint (flammable liquids) with a small portion of the solvent replaced by water and a few additives to make it work. Latex wall paint is another matter, but not often used in an industrial spray operation. Some latex paints actually exhibit a flash point but do not burn further after the initial flash. Some burn pretty impressively in the spray pattern.
 
PS: Very few AHJs or insurance inspectors are familiar with spray booths and spray operations. This does not absolve anyone should trouble arise later. Make sure you are in full compliance with article 516 at the minimum. If/when a fire occurs, and if there is an injury or significant property damage, everyone that had anything to do with the installation will hear from the lawyers. And even if the employer is exempt from liability courtesy of workers compensation, contractors and their subs are fair game.
 
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