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#84767 - 05/02/03 10:23 PM Spray Booths  
sparkync  Offline
Joined: Oct 2002
Posts: 828
Sorry to start another thread on the same subject I did a few nights ago, but I thought under a different heading I may get more responses... I am trying to figure out the wiring that is required around a spray booth. I am looking at the code requirements and am trying to distinguish the class and division that I am working in.
There will be at least 1 spray booth with an exhaust fan to the outside. Am I correct in my interpretation of the code that inside the spray booth is a Class I Division I classification, and around the spray booth up to 20 ft. and over the spray booth up to 10 ft., is a Class I Division II location??? Thus the wiring method cannot be EMT, but must fall under one of the requirements in 501-4b, rigid metal conduit, threaded steel intermediate metal conduit, etc.....
But if I go outside the 20 ft. distance, I do not have to use any special enclosures for 2 stop start stations I intend on installing for the exhaust fans outside???
Also any pipe going through the Class I Division II location to an area that is unclassified ( or beyond the 20 ft. horizontal or 10ft. vertical, must have a seal off within 10 ft. of the boundary on either side and that pipe must be rigid or threaded steel conduit where it leaves the Class I Division II location....??? If the seal off is 10 ft. on the outside boundary, it can be changed over to EMT?????

Does any of this make sense [Linked Image]
I think I need a course just on hazardous locations [Linked Image] Boy it's hard to decipher some of the wording in the code sometimes....

Looks like if I've interpreted it right, I have a lot of changing of the existing wiring to conform to code....... Well if anyone wants to respond to see if I've got it straight, I would appreciate it, but if it confuses you like it's trying to confuse me... I understand.... Thanks again.... Steve

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#84768 - 05/03/03 02:59 PM Re: Spray Booths  
dana1028  Offline
Joined: Jan 2002
Posts: 163
San Carlos, CA
Steve - it sounds like you have it correct; your explanation was very clear. I've done some work for an autobody paint shop and the installation methods you mention is how we did it.

By the way - there is a book out just on the subject of wiring methods in hazardous locations - I saw it at (1993 code) reasonably priced [$10-15?] I used their search engine - 'National Electric Code' and that book came up on a long list of books available.

#84769 - 05/03/03 05:18 PM Re: Spray Booths  
walrus  Offline
Joined: Jul 2002
Posts: 680
Bangor Me. USA
Doesn't a wall stop the Class 1 D1 area, the conduit would penetrate the wall and first fitting would be a seal off and transistion to whatever legal method of conduit?

#84770 - 05/04/03 10:05 AM Re: Spray Booths  
US Coreman  Offline
Joined: Mar 2003
Posts: 36
Illinois, USA
Perhaps this link to an Appleton Electric page on Class 1 Area with Flamable Vapors will help.

They also used to publish a NEC Review which was an invaluable book explainging and attempting to demistify the HazLoc picture.

I hope these help.


[This message has been edited by US Coreman (edited 05-04-2003).]

#84771 - 05/04/03 06:22 PM Re: Spray Booths  
nesparky  Offline
Joined: Jun 2001
Posts: 642
Before you start get with the local AHJ. Some have definate ideas and/or local admendments for these area. This can be a very expensive mistake if you do not do this. Also find out all the details of the spray booth. Some have light windows and installed water fall venelators. The last two I installed were set up this way, they required NO explosion proof work. All the electrical was outside the booth and the booth doors had to close to allow the air to get to air taps inside. [Linked Image]


#84772 - 05/07/03 06:50 AM Re: Spray Booths  
sparky  Offline
Joined: Oct 2000
Posts: 5,311
There's an antique joint downtown here that sprays all day long with nothing more than a window box fan

I suspect the workers in this 12x20 shack have some permanent physical damage

They always have headaches, and many times there is a visible fog.....

I've pulled a number of permits working around this place , the state simply waltzes by this obvious hazard

#84773 - 05/14/03 10:44 AM Re: Spray Booths  
electricwonder  Offline
Joined: Apr 2002
Posts: 22
New Martinsville, WV, USA
I have done some work with paint/spray booths, a very handy reference is NFPA 33, dealing with this subject.You should be able to find this book anywhere you would buy your NEC code book, they are put out by the same people. The pre-made booths are nice, as they do contain the hazardous location to inside the booth, and all wiring can be done in EMT or MC cable. However, if you are making your own, get a copy of NFPA 33, and follow it, it will keep you off of the inspectors black list, and most importaintly, keep every one alive and well. Good luck, Greg

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