Wiring classification for sanding and glassing rooms

So I am in the process of building a new garage that will have a sanding room and glassing room.  I just had an electrical inspector ask me about the classification of the rooms. Something about section 18 and 20 hazardous materials.  This would not have been an issue but he saw my large fan in the corner of the room and asked why I had it.  I said I was going to sand a few boards. He associated this with spraying lacquers etc and and said I needed different wiring and fixtures.

He said I can get an engineers stamp to declassify the area.  I always thought and told him that sanding dust was inert and not a fire hazard.  I know the acetone is very dangerous but can someone tell me how they treat their dust in terms of special electrical considerations.  I think this guy is just being a pain in my but, however I want to be safe.

Sanding dust is EXPLOSIVE  !

Hopefully you learned one good lesson…don’t tell government officials anything they don’t need to know.  Second, don’t outfit a space until you have your CO.  If he asks what the fan is for, the correct answer is to keep the garage cool on hot days.

How do you say?  Da foot in da mouth.  Now he will never leave you alone.  Even if you tell him you have abandoned the idea of doing surfboards.  Mako is 100% right.

You always want to be safe, but the less they know the better.

Too late to go back as you say but this is overkill for a backyard guy doing 10 boards per year.  I know there are examples of fire with acetone in the surfboard busiess but are there any examples of explosion from sanding surfboards?  

Wire it for residential.  Space the plugs appropriately down the wall and tell the inspector he scared the shit out you and you have abandoned all plans to do anything but park a car in your new garage.  I’m sure that someone here has some scary story about explosions due to sanding dust, but in forty years  of being around some of the most clandestine and backyard operations you’ll ever come across, i have yet to hear of one burning down due to dust. add a cigarette, a roach, open cotainers of Acetone;  Yes all bets are off.  that’s what the 5/8’s sheetrock is about.  There’s always more to the story.  Lowel

Right on Lowel.  This is the route I am going to take.

In my foolish youth, I did an ‘‘experiment’’ with some sanding dust.         I took about a half cup of sanding dust, threw it in the air, then tossed a lit match into the dust cloud.       WHOOSHHH !      A quite impressive fireball.      Like Lowel, I’ve not heard of a sanding room explosion, but that doesn’t mean it can’t happen.      All it takes is a spark in the right particulate density, in suspension in the air.   

Technically, flammable dust and vapors are separate classifications in the electrical codes.  Normally these are addressed by NEMA explosion-proof outlets and switches which have all sorts or weird configurations.  The codes also include wiring within the walls as well.  There’s a few firefighters on this site that know more about typical inspection criteria for shops than me.  If it’s just  personal precautions rather than regulations, use the hospital switches and outlets for oxygen-rich rooms ($$$).

Although foam/sanding dust and solvent vapors will spontaneously combust, it rarely if at all happens in normal work.  It takes really low ventilation, a very messy area, shorted tool, or some other set of  circumstances.  If you’re using a garage with a big door that gets opened periodically its not like you’re working in a coal mine where explosion-proof electricals are truely needed. 

Now there have been some serious fires that have burned down shops (and homes), but most have been some electrical problem (wiring or tool) and just spread more quickly due to the dust and vapors.   Most happen when nobodys there, so shut off the main breaker when you leave and use common sense on leaving buckets of curing resin sitting around or flamable stuff near hot things like compressors.  And a clean shop is a safe shop.  Vacuum systems absolutely need to be grounded;  those static shocks are tiny arcs.  

Sorry for the drift but the story is relevant.

Years ago I worked in the film and tv biz building sets, props etc.

  We were shooting on location at a ranch in the Santa Susana area and the property owners had allowed the fx team to rig one of their barns to blow out the made for the shot doors and windows to be replaced after filming.

Problem was they neglected to vacuum and dust out the barn. It was blown literally to smithereens. 

The owners just looked at the DP and said I hope your insurance is good.

Thankfully they got the shot and nobody was hurt.   

BIG BOOM!

Medium Density Fiberboard (MDF) dust is HIGHLY flammable and explosive not only because of the particulates but the glue binder adds more volitility to it. I’ve seen idiots play with it and almost set the job on fire. Uncle Grumpy, that is where I grew up on the valley side of the pass. Know those spots like the back of my hand; Corriganville. Studio Rd. in Box Cyn. and Spahn Ranch. As kids, we knew Shorty Shea the caretaker of Spahn in the day of infamy. Roy Rogers had his ranch close to there also. When they sold and subdivided, they named the streets after them. Roy Rd., Dale court, Trigger and Bullet lanes. When it was wide open it was a great place to be a kid. Zorro’s adobe house still stands today and has a million dollar view across the San Fernando Valley. Progress, progress.

deleted. It was a stupid comment

At work we have a sanding booth and the safety people won’t let us have anything electrical inside the classified ‘dusty environment’ even though the fan is like a hurricane …sounds like the same sort of thing you are running up against with the code inspector…sometimes it’s enough to make you go cookoo!

I would have loved to hear it.  Lowel

Lam up a couple of boards on the racks.  Strike a match and see what happens.   Any takers for a little experiment??