ECN Forum Forums Code Related Discussion NEC & other Code issues Spray Room vs. Open Spraying

Hello, all! This is my second post to the site, so please bear with me...

I've searched the forums, and cannot find the answer to my dilemma. One of my bosses is asking me to source and price some luminaires to use when we convert an existing room to a painting area at work. It's a fairly large room (approximately 20'x35') with cinder-block walls, concrete floor, and steel ceiling (14' high). The room has a man door on one of the long sides, and 8'x8' counterweighted stainless-steel-clad sliding doors (for forklift access) on the opposite long side and one of the short sides (the opposite short side is an exterior wall, through which the outbound ventilation will pass). All electrical equipment (panels, discos, pipe, switches, etc.) will be removed, with the lighting to be attached to the walls (wiring to pass through said walls), and mounted 8'-12' from the floor. The largest object we will paint in there is a platform top which is about 8'x20'x1' made of heavy-gauge steel.

I understand the classification/division system(s) to be employed when specifying electrical equipment in Hazardous and Classified Locations. My question has to do with definitions. Specifically, how big does an area have to be to qualify for "Open Spraying" classification?

Using 505.5(B)(1) and (2), 516.3(B)(1), and 516.3(C)(1), it's plain that this will be a Class I location, but Division 1 or 2? If this can be classified as Class I, Division 2, our cost for luminaires will be approximately 20% of the cost of luminaires rated for Class 1, Division 1. The boss will scream bloody murder if he has to pay $2k+ per luminaire, though I greatly fear that's how this area will have to be classified.

Please help me resolve whether this area must be classified as a "Paint Room" or can be classified as an "Open Spraying" area. I'll be happy to supply additional information as needed.

Thank you all very much!

Paul

You mention an exhaust in the room, that would lead me to call it a spray room.
Will there be an air make up system , or will all the gas appliances in the building just back draft during the winter ?
One suggestion to reduce the problem, Latex paint.
Also look at section 516.4 (C) I have seen some very inventive construction to keep the lights out of the spray room.
Interlocking the ventilation and compressor for the sprayer can sometimes influence the classification check with the Building officials.
good luck
Alan--

I recall during my apprenticeship, the text was quite specific : It is NEVER the electricians' responsibility to determine the classification of hazardous locations."

That's what the book said. Yea, right. In the field, we are often far more qualified than anyone else involved, without regard to whatever credentials the others may hold!

Anyway.... determining the classification requires a whole bunch of things be considered. How much is sprayed, what the airflow is, whether there is a "water wall" or not, and WHAT is being sprayed.

Once an area is defined as "classified," then there are a whole slew of ways to deal with it.... and not all require special wiring methods.

When you are in "over your head" (it happens to me all the time), you need to get together with some REAL experts. So, how do you find them?

You might ask some local place with similar issues who their consultant is. IE: Is there an oil refinery near you?
The ISA (Instrumentation Society of America) has LOTS of expertise in this area. Ask them for a local, sertified member.
Finally, your insurance company has rooms full of folks who do nothing but worry. Ask them.

If you are using solvent based coatings then it is classified Class 1, Division 1, Groups 3 & 4.

With that said and a 30 year background in finishing rooms, I really like the water based coatings suggestion the best.

Talk to your boss about buying the whole booth with electrical pre-installed including lighting & ventilation. It's what everyone is doing around here. It's all approved for use by the manufacturer and only needs normal power hookup outside the hazardous classified area.

Dave

Thank you all for your input. I'll take all of this information under advisement, and see which direction the boss wants to go. His say is, of course, the final say on what we do. :-|

I think, ultimately, it'll be a competition between how much money he wants to spend and doing the job to Code. He is, understandably, leery of bringing anyone official into the plant, as we've been "cowboyed" into a certain indefinite red flag over the years. I'm fixing things as time and fundage allow, but we're still a long way from things being kosher with all but the blindest of inspectors.

What I have seen on many prefab booths is the standard flo troffer is mounted on the outside of the booth and the light shines through a plexi panel that is cut into the steel and has been bolted and sealed inplace. My guess is that all of this is to keep the classified area inside. All of the electrical outside is then run with EMT or MC whips.
Also, every booth includes a compressed air interlock with a 5 sec delay. I presume this is to allow the sprayer to finish the pass before air is shut off if someone opens the door.

I really cannot stress enough the need for this application to be reviewed by a real expert (and I do NOT consider myself one!).

Just for illustration, let me describe a few different systems I've seen systems that had engineering and AHJ approvals:

A manufacturer of pool equipment sprayed some items with epoxy; others were powder-coated. In neither case was it necessary for special wiring.

A body shop constructed a booth. Lights were outside the booth, shining in through windows. Fans were driven, by belts, by motors outside the ducting. Only the fan switches need to be "rated."

A manufacturer sprayed his products inside the plant. The paint- an older solvent-based enamel- was applied in an area open to the rest of the plant, with minimal curtain separation. The wall immediatley behind the spray area was continuously washed with flowing water (a "water wall"). I do not recall any special electrical equipment, or ventilation. The "water wall" was exceptionally efficient at capturing overspray and fumes.

With these examples in mind, it is quite possible that the spray area has a very limited "classified" zone.

There is no substitute for professional judgement.