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#103746 - 11/08/02 06:54 AM Bewildered! Designed by the Woodshop Supervisor  
Joe Tedesco  Offline
Member
Joined: Oct 2000
Posts: 2,749
Boston, Massachusetts USA
[Linked Image]

Bewildered! Designed by the woodshop supervisor!

The explosion proof switch probably costs more than the saw equipment.


Joe Tedesco, NEC Consultant

2017 / 2014 NEC & Related Books and Study Guides

#103747 - 11/08/02 08:32 AM Re: Bewildered! Designed by the Woodshop Supervisor  
jdevlin  Offline
Member
Joined: Aug 2002
Posts: 402
welland ontario canada
Sawdust can be an explosion hazard just like grain dust if it is fine enough.


#103748 - 11/08/02 08:55 AM Re: Bewildered! Designed by the Woodshop Supervisor  
Joe Tedesco  Offline
Member
Joined: Oct 2000
Posts: 2,749
Boston, Massachusetts USA
True

Quote
Class III locations usually include textile mills that process cotton, rayon, and so on, where easily ignitible fibers or combustible flyings are present in the manufacturing process. Sawmills and other woodworking plants, where sawdust, wood shavings, and combustible fibers or flyings are present, may also become hazardous. If wood flour (dust) is present, the location is a Class II, Group G location, not a Class III location.
www.necdirect.org




[This message has been edited by Joe Tedesco (edited 11-08-2002).]


Joe Tedesco, NEC Consultant

#103749 - 11/08/02 10:07 AM Re: Bewildered! Designed by the Woodshop Supervisor  
spyder  Offline
Member
Joined: Oct 2002
Posts: 210
Massachusetts
Better safe than sorry. But still seems a little extreme.


#103750 - 11/08/02 10:35 AM Re: Bewildered! Designed by the Woodshop Supervisor  
Redsy  Offline
Member
Joined: Mar 2001
Posts: 2,056
Bucks County PA
There's more to this than meets the eye.
That sure looks like a Class 1, Div.1 disconnect. What about the conduit seal?
What about the NEMA 12 enclosure fed by
sealtite?

Let's play "Guess the Classification"

[This message has been edited by Redsy (edited 11-08-2002).]


#103751 - 11/08/02 03:36 PM Re: Bewildered! Designed by the Woodshop Supervisor  
SAFTENG  Offline
Member
Joined: Sep 2001
Posts: 136
Cincinnati, OH, USA
I thought that saw dust would have fallen into Class II locations. Class I is flammable vapors and gases, Class II is dust, and Class III is Ignitable Fibers and Flyings??? Although wood dust is not exclusively mentioned in the UL classifications, would it not be considered a Class II location. Just asking the elctrical experts.

Bryan www.SAFTENG.net


#103752 - 11/08/02 06:07 PM Re: Bewildered! Designed by the Woodshop Supervisor  
JBD  Offline
Member
Joined: Jul 2001
Posts: 599
WI, USA
The simple presence of wood saw dust does not create a Class II hazardous location. If it did all of our circular saws and sanders would need to be dust ignition-proof.

According to Killark's 1999 National Electrical Code Review & Application Guide " To be considered a "dust" the combustible material must exist as a finely divided solid of 420 microns (0.420 mm) or less. Such a dust will pass through a No. 40 U.S. sieve."


#103753 - 11/08/02 08:46 PM Re: Bewildered! Designed by the Woodshop Supervisor  
Roger  Offline
Member
Joined: May 2002
Posts: 1,716
N.C.
The dust shouldn't be a problem in this case.

Check out the below floor dust collector.

But look in the background, there's another one of these switches.

BTW, The band saw is mighty high dollar itself.

Roger


#103754 - 11/11/02 07:13 AM Re: Bewildered! Designed by the Woodshop Supervisor  
Trainwire  Offline
Member
Joined: Mar 2002
Posts: 360
Strasburg,PA,USA
Are you sure we are looking at just a disconnect?
That gizmo sure looks like a rotary three phase converter to me.
But then I have been known to be wrong, on numerous occasions [Linked Image]

TW


#103755 - 11/11/02 08:32 AM Re: Bewildered! Designed by the Woodshop Supervisor  
Redsy  Offline
Member
Joined: Mar 2001
Posts: 2,056
Bucks County PA
Roger,
Good eye with the additional disco. Also, above the (non-xp)panel is what appears to me an explosion-proof j-box of similar classification.
Either somone got a deal on surplus or stolen materials, or some contractor sold the owner a line of bull.

[This message has been edited by Redsy (edited 11-11-2002).]


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