# Welding shop Division 1 Class 2?



## itsunclebill (Jan 16, 2007)

You need to check with the AHJ, but welding shops do not meet the definitions of "handling" (implies warehouse) or "processing" (manufacturing or transferring gasses between vessels). And, in the event class 1 type conditions were present the first use of a striker would make the question a moot point. Every welding shop I've wired used a commercial garage classification for wiring rules.


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## dawgs (Dec 1, 2007)

My guess is it's not a classified area.


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## don_resqcapt19 (Jul 18, 2010)

dawgs said:


> My guess is it's not a classified area.


And if it is, there are a lot better ignition sources than the electrical equipment


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## backstay (Feb 3, 2011)

itsunclebill said:


> You need to check with the AHJ, but welding shops do not meet the definitions of "handling" (implies warehouse) or "processing" (manufacturing or transferring gasses between vessels). And, in the event class 1 type conditions were present the first use of a striker would make the question a moot point. Every welding shop I've wired used a commercial garage classification for wiring rules.


Commercial garage classification? Please explain.


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## jigs-n-fixtures (Jan 31, 2013)

Class 1, due to the acetylene. Division 2, because it isn't normally at high enough concentrations to be explosive, but could accidentally become so in the event of a failure. 

Depending on the quantities they anticipate and the size of the room, the AHJ might be willing to require it for only a portion of the space. One possibility is a dedicated tank storage room. This would limit the potential for explosion to a smaller area.


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## MWayne (Nov 8, 2010)

Thanks for all the help, however I was hoping by now that someone would have said "look in NFPA XX pages such and such and there'll be the defining wording". Maybe there is no guidance on this situation?


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## FaultCurrent (May 13, 2014)

Just think about the question. Welding will be either be electric arc, or flame oxy-acetylene. Or could be high tech like laser or high voltage. All encompass an ignition source. How could a welding shop be classified and if it was than nobody could weld in there.

Acetylene gas is super explosive. It is dissolved in acetone inside the welding gas cylinders. It is too unstable to be compressed as a pure gas. The only way an area could be a problem would be with a major leak or some body leaving the torch open. 

Even if you wanted to make it a classified area what fittings are approved for use in a Group A atmosphere?


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## MWayne (Nov 8, 2010)

FaultCurrent said:


> Just think about the question. Welding will be either be electric arc, or flame oxy-acetylene. Or could be high tech like laser or high voltage. All encompass an ignition source. How could a welding shop be classified and if it was than nobody could weld in there.
> 
> Acetylene gas is super explosive. It is dissolved in acetone inside the welding gas cylinders. It is too unstable to be compressed as a pure gas. The only way an area could be a problem would be with a major leak or some body leaving the torch open.
> 
> Even if you wanted to make it a classified area what fittings are approved for use in a Group A atmosphere?


What we want is an out for not having to classify it at all, it appears what you're saying is that since acetylene is involved then there is not anything made to comply with article 500. Correct?


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## FaultCurrent (May 13, 2014)

Exactamundo. 

If you have an acetylene generator room (unlikely) you can't put any wiring in it. Big factories that used a lot of gas welding like aircraft manufactures used carbide gas generators. Like the old Bangsite cannons toys we used to have as a kid.

But for the welding shop you need NFPA 51 to refer to so you can justify not classifying the shop area.


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## MWayne (Nov 8, 2010)

The boss said this matter was turned over to an engineering firm who will write a CYA paper for us basically stating the use of standard shop wiring practice will be acceptable. Thanks for all the help!


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