NEC 502.4(B)(4) requires all boxes and fittings to be "dusttight". NEC 500.2 defines dustight as "enclosures constructed so that dust will not enter under specified test conditions". It has a fine print note:
FPN: See ANSI/ISA 12.12.01-2000, Nonincendive Electrical Equipment for Use in Class I and II, Division 2, and Class III, Divisions 1 and 2 Hazardous (Classified) Locations , and UL 1604-1994, Electrical Equipment for Use in Class I and II, Division 2 and Class III Hazardous (Classified) Locations.
I would assume the ANSI/ISA 12.12.01-2000 deals mostly with instrumentation. Looking at the scope of UL 1604-1994 (not wanting to pay over $500 just for the standard) it appears that UL 1604 applies mostly to equipment and not to enclosures just by themselves (although the equipment may be in an enclosure).
I would normally assume that a NEMA 4, 6, or 12 enclosure would be "dusttight", however the Hoffman Catalog in their NEMA standards table for applications specifically mentions "non-hazardous" and also states that for dust, lint, fibers, and flyings that they are not to be Class II.
I have not seen any enclosures specifically UL 1604 listed. MY QUESTIONS ARE THESE: What do most people use for boxes and enclosures in a Class II, Division 2 location? Does anyone know of enclosures specifically rated for Class II, Division 2 locations? PLEASE NOTE THAT "DUSTTIGHT" IS NOT THE SAME AS "DUST-IGNITIONPROOF", WHICH IS A NEMA 9 CLASSIFICATION OR EXPLOSIONPROOF WHICH IS A NEMA 7 CLASSIFICATION.
FPN: See ANSI/ISA 12.12.01-2000, Nonincendive Electrical Equipment for Use in Class I and II, Division 2, and Class III, Divisions 1 and 2 Hazardous (Classified) Locations , and UL 1604-1994, Electrical Equipment for Use in Class I and II, Division 2 and Class III Hazardous (Classified) Locations.
I would assume the ANSI/ISA 12.12.01-2000 deals mostly with instrumentation. Looking at the scope of UL 1604-1994 (not wanting to pay over $500 just for the standard) it appears that UL 1604 applies mostly to equipment and not to enclosures just by themselves (although the equipment may be in an enclosure).
I would normally assume that a NEMA 4, 6, or 12 enclosure would be "dusttight", however the Hoffman Catalog in their NEMA standards table for applications specifically mentions "non-hazardous" and also states that for dust, lint, fibers, and flyings that they are not to be Class II.
I have not seen any enclosures specifically UL 1604 listed. MY QUESTIONS ARE THESE: What do most people use for boxes and enclosures in a Class II, Division 2 location? Does anyone know of enclosures specifically rated for Class II, Division 2 locations? PLEASE NOTE THAT "DUSTTIGHT" IS NOT THE SAME AS "DUST-IGNITIONPROOF", WHICH IS A NEMA 9 CLASSIFICATION OR EXPLOSIONPROOF WHICH IS A NEMA 7 CLASSIFICATION.