I have a wood working plant I am getting ready to do some wiring on, and wonder if someone could help me on the code issues here. It is a building that is being modified for wood working. Mainly machines are being hooked up, and a 200 amp. 460 volt panel set. My main concern here is the wiring associated with "hazardous locations". I haven't at this time been able to research all the information needed, but it looks like this would fall under a Class 3 location. There will be disconnects set and emt etc. Could someone refresh me on the wiring, fittings etc. that is to be used? I looked in the customer's other building he has, and as all wood working plants, ( furniture frames etc. ) it is covered with wood fibers and saw dust. ) Thanks for any input. Hopefully I will have more time to research this before I have to start the job. He is pushing the work, because he wants in the building as soon as possible, yesterday Thanks again... Steve.
In general saw dust is too coarse to be "explosive". The dust for Class II locations is very very fine like what is found in the vacuum system (sometimes it is called flour). Vendors like Killark, Appleton, and Crouse-Hinds all have information to help you evaluate hazardous location requirements. But always the final classification is up to the AHJ, which sometimes in cases like this is the local fire department.
Sparkync, Because you stated that the building is being modified for wood-working, I would approach this VERY carefully, and make sure the AHJ is involved. This is probably a change of occupancy to a Hazardous classification. The UBC (yes, I'm in Calif.)would class this as H-2, moderate explosion hazard or hazard from accelerated burning. The I-code treats it similarly. NEC 500-8 classes it as Class III Div 1, AT LEAST!!!
Got in touch with AHJ and he informed me that if the owner had a "dust collection system" on All of his machinery, that the wiring would be standard, but noted that every single piece of equipment would have to have it, no exceptions. Thanks for the replies... And yes, I'm trying to enter this very carefully. There has already been some wiring done and I haven't really took a good look at it yet. I'm suppose to get a little deeper today.
First of all, wood working areas usually need a much tighter sprinkler patern than whatever was there before.....make sure the fitters do their thing first. Secondly, the primary concern in testing Class 3 eqt is that it never get hot enough to ignite the dust....even when it's buried in it. In a wood shop, this would apply primarily to motors; all motors should be of the TEFC type. Some other things -lighting, for instance- can also get hot enough to be a concern. Finally, there are likely to be alarm requirements, as well as control issues (automatic operation of dust collector, no auto re-start, etc) to address as well.