Paint Booth Light Fixture Wiring

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dnbob

Senior Member
Location
Rochester, MN
We are wiring a new partially open front, closed top (& side)paint booth. The ceiling is primarily filters for the fresh air supply, with a fresh air plenum above. My inspector is considering the air plenum as Class I Div I as he doesn't consider the area above the filters to be unclassified. It is a down draft system, and the exhaust air is not recirculated.
The fixtures the Mfr provide are class I Div II fixtures.
I saw in an older post they were using 4 sq.'s & MC cable in that space, and in their situation the air was recirculated.
Trying to understand wiring methods for this area.

Thank You.
 
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GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
The possibility of flammable vapor above the filters basically depends on whether the ventilating fan(s) are on or not.
Lighter than air vapors can pass through the filters and accumulate if the fans are not on, even though droplets may not.

More importantly, has a qualified person (not just the average electrician, EE, or EC) made a classification determination of the area? Your job is to wire correctly for the applicable classification, not to determine that classification.
And the inspector may or may not be qualified to make that determination either. But in the absence of a formal classification by qualified person you do not have any way to dispute the inspector's decision.
 
ptonsparky

ptonsparky

Tom
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
EC - retired
GoldDigger said:
The possibility of flammable vapor above the filters basically depends on whether the ventilating fan(s) are on or not.
Lighter than air vapors can pass through the filters and accumulate if the fans are not on, even though droplets may not.

More importantly, has a qualified person (not just the average electrician, EE, or EC) made a classification determination of the area? Your job is to wire correctly for the applicable classification, not to determine that classification.
And the inspector may or may not be qualified to make that determination either. But in the absence of a formal classification by qualified person you do not have any way to dispute the inspector's decision.
Click to expand...
Nor do you want to.
 
M

MTW

Senior Member
Location
SE Michigan
How you handle the fresh air plenum is install an solenoid interlock for atomization air on the air supply line. You are likely to see instructions to that effect in the light fixture packaging, or booth instructions.

The fixtures are Div 2 rated, they cannot be installed in a Div 1 location. Most fixtures have a magnetic lens door switch to disable power in the event that the fixture gets gets opened.

If you can’t spray paint, unless the ventilation system is running, and is is proven running, the supply air plenum cannot fill with solvent vapors. This has been standard procedure on paint booths for many years. Therefore Div 2 fixtures are fully suitable, read the fixture and booth instructions.
 
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dnbob

Senior Member
Location
Rochester, MN
Thanks for the replies. I printed off some NFPA 33 information and was able to get things resolved. My inspector had seen a partial picture of the booth without the fresh air ceiling filters and didn't realize they had not been installed yet, so was mostly confusion as to where the ceiling line actually was.
 
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