Class 1 Div 2 Enclosures

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Richard S

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Excuse my Article 500 ignorance, but I need a sanity check. I can't find where the code lists acceptable juction boxes for a Class 1 Div 2 area.
Per 501.10(B)(4) Boxes and Fittings "Boxes and fittings shall not be required to be explosionproof except as required by 501.105(B)(1), 501.115(B)(1) and 501.150(B)(1)
Per 500.8(A)(3) Where specifically permitted in Articles 501 through 503, general-prpose equpment or equipment in general purpose enclosures shall be permitted to be installed in Division 2 locations if the equipment does not constitute s source of ignition under normal operating conditions."
Does allow for the use of a 4 square box for a pulling or junction box as long as it doesn't contail any arcing devices or devices that may cause ignitian by surface temperature? The commentary imediately following 510.10(B)(4), mentions "Where general purose enclosures and permitted...", but I can't seem to find a definition of "general purpose enclosure". I've looked the forum and noticed the reference to nema 4 and 4x multilple times for C1D2 areas, but can't find a reference in the code at all. Can someone refer me to where the code may list acceptable enclosures for Class 1 Div 2 that will be used for pulling and possibly splicing of branch circuits (any arcing device will be in explosion proof enclosures with approprate sealing). I have a hard time envisioning using rigid conduit and a 4 square box.
 
I think you can infer from 501.10(B)(3) that you need a gasketed box. Some may argue the black and white of what the code says or doesn't say. There may be some environments where the 4 square may be suitable, but I don't work in those environments.
 
Technically, the problem with a four-square box in Division 2 is the methods most commonly used to bond it. See Section 501.30(A) and its futher references via FPN to 250.100 and 250.92(B)(2)-(4).
 
I am currently planning a installation in a C1D2. My interpritation was to go ahead and use the gasked type J boxes and condulets and IMC conduit. I am however planning on using 4/s boxes, and EMT w/ set scew fittings for an intrinsicly safe system.
 
If the box is otherwise suitable for the location were it not classified Class I, Division 2, there is no prohibition or restriction other than it be bonded properly. Of course, the additional hardware and labor necessary to bond it properly will usually lead to using more appropriate materials.
 
I'm sorry I missed your post here yesterday (7/29/09) It is still important to observe that many J-boxes will also need the auxilliary bonding as described in 501.30, gasketed or not. Threaded conduit bodies are usually fine.

Intrinsically Safe systems do eleminate many Hazloc headaches; however, there are still several, grounding, bonding and sealing issues that need to be observed - See Art 504. It isn't too long and will clarify what I'm saying.
 
Richard S said:
but I can't seem to find a definition of "general purpose enclosure
Click to expand...

A General Purpose Enclosure is just a plain old enclosure. All they're saying is that General Purpose Junction Boxes can be used in Class I Division II locations if there are no arc producing devices or even sparks inside the box. These could cause an explosion.:wink:
 
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