Class III Division 1

[blues]

I am in the process of reviewing an existing woodworking facility that has an order to comply with Class III Div 1. I was wondering if it would be possiable to suggest some type of air transfer system that might be less expensive. What would the criteria be? If not I will have to suggest dusttight receptacles and distribution equipment.

Also I can not confirm if the material is not cumbustible dust ( 420 microns or less) after reviewing the product safety data sheets.

Any help or comments relative to these to issues would be appreciated.

Dan Craven

 

[rbalex]

First, there is no external Standard to refer to directly to determine Class III electrical area classification; it is left almost entirely up to judgment. Second, when one recognizes that the application of 503.10 (B) Exception is virtually non-existent, then it is obvious that there is no discernable difference between Division 1 and Division 2 installations in Class III locations. Third, unless there is a great deal of fine sanding the probability of a Class II (particles 420 microns or less) situation is very low.

I hate Class III. I have never once seen a location properly classified as Class III, except in a few textile type operations – never in any woodworking facilities. It has always been done for an unqualified someone’s “warm fuzzies.”

As I said, there is no true standard I am aware of to determine a Class III location; however, many of the duplicate concerns and all of the critical ones are covered in NFPA 499. This is why Class II and III materials are lumped together now in the Zone equivalent Article 506.

With good housekeeping techniques, virtually nothing in a woodworking facility needs to be classified – even when particles 420 microns or less may be generated.

Edit: Corrected NEMA 499 to NFPA 499

 

[muskiedog]

Clean Clean Clean

Clean Clean Clean

I worked in a printing plant that also had a fabrication shop. It is amazing how much dust accumilates. We did install dust tight receptacles due to inspections showing that there was quite a bit of dust accumilation. Even with a good vacuum system you will always need to have some type of cleaning schedule if you do not have one now. Every week floors and equipment cleaned thoroughly. Every 3 months at a minimum we vacuumed the over head rafter and support structures. Any place the dust can settle.