approved receptical boxes and switch boxes

I have a grinding room in a grain mill that is being rewired. The area is classified as class 2, division 2 group g. I am new to hazardous work and this may be a dumb question, can an outdoor box be used in this area to satisfy the requirment for a dust proof -ignition proof box. I would like to use these boxes if possible complete with flip covers for the recepticals, and the sealed switch covers for my light switches. I am told by the inspector that vapor-tight is required for the lights which essentially uses this type of box for the lights.
 

rbalex

Moderator
Staff member
You really need to start studying Article 502. So does the inspector since vaportight is meaningless in Class II. See Section 502.130.

In Class II, Division 2 the receptacles are not required to be dust-ignitionproof. However, simple outdoor construction is not adequate either. See Section 502.145(B)
 

renosteinke

Senior Member
Perhaps we have different codes. My NEC 502.145(B) refers to receptacles and attachment plugs, and is silent as to junction boxes and lights.

In any event, 502.145(B) seems deliberately vague, and appears to allow simple 'outdoor' "Bell" boxes and flip-covers for receptacles in Division 2 locations.

This would be consistant with 502.115(B), which only requires switches in Division 2 locations to be dusttight. 502.10(B)(4) calls for the junction boxes to be simply 'dusttight.'

Let's review this in terms of what is involved in testing a product for use in a Class 2 location. The testing has one primary requirement: that you be able to bury the item in the flammable dust, then operate it for an extended time, without anything becoming hot enough to ignite the dust.

Where there's no heat normally produced - as in a junction box - it's pretty hard to fail this test. Where great amounts of heat are produced - say, by a light bulb - the challenge is to keep the dust far enough away to prevent it from getting hot enough to ignite.

"Vaportight" may not appear in the code, but 'dusttight' does, regarding lights, in 502.130(B)(2). I submit that any design that will keep out vapors will also keep out any dust, however fine.

Please note that there is a tremendous amount of leeway for 'division 2' locations. Make it 'division 1' and a lot of your discretion goes away.
 

don_resqcapt19

Moderator
Staff member
...
"Vaportight" may not appear in the code, but 'dusttight' does, regarding lights, in 502.130(B)(2). I submit that any design that will keep out vapors will also keep out any dust, however fine. ...
Keeping the dust out is not the only issue for a light fixture in a Class II location. The surface temperature is a very big issue for that application.
 

don_resqcapt19

Moderator
Staff member
...
In any event, 502.145(B) seems deliberately vague, and appears to allow simple 'outdoor' "Bell" boxes and flip-covers for receptacles in Division 2 locations. ...
I don't see how you could use that type of receptacle.
(B) Class II, Division 2. In Class II, Division 2 locations, receptacles and attachment plugs shall be of the type that provides for connection to the equipment grounding conductor of the flexible cord and shall be designed so that connection to the supply circuit cannot be made or broken while live parts are exposed.
A standard receptacle cannot meet that part of the rule. The blades on a standard plug are energized before they are fully inserted into the receptacle.
 
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