class 2 div 2 2

[wyerdup]

I have a project in a feed mill and most of the building is class 2 div 2. My question is, do standard fittings with gasketed covers (LB's & T's) meet the dusttight requirement of the NEC? Also it appears that I can use NEMA 12 boxes, but I am unsure if I am permitted to make slices in that type of enclosure. The handbook explanation for 502.10b4 indicates no splices, but the code section really only sayes boxes must be dusttight.

 

[7anoter4]

According to NEC 502-4 (b) (1) Wireways, Fittings and Boxes..."in which taps,joints or terminal connections are made shall be designed to minimize the entrance of dust and (1) shall be provided with telescoping or close-fitting cover or other effective means to prevent the escape of sparks or burning material and
(2) shall have no openings (such as holes for attachment screws) through which, after installation, sparks or burning material might escape or through which adjacent combustible material might be ignited." So only NEMA 9 box is suitable [approved or not as dustignition proof] and hazardous location fitting like also approved or not.

 

[resqcapt19]

7anoter4,
The last code to use the wording you are quoting was the 1999 NEC. The 2002 and newer codes do not use that wording and simply require a "dust tight" enclosure for fittings and boxes used in a Class II, Division 2 location. I would consider the fitting shown in your post to be "dust tight".

 

[7anoter4]

Thank you resqcapt19.It seems that the newer Editions agreed with General purpose dust-tight enclosure types as defined by UL 50 and NEMA 250 [Types 3, 4, 4X, 12, 12K, and 13] for class II Division 2.
So NEMA 12 is suitable.
I still don't know how the splice may to be done now: bare or insulated

 

[itsmoked]

Hi 7anoter4.
I too was surprised to see that gasketed LB not being allowed so thanks resqcapt19.

I believe the intent here is no arcing sparking in normal operation and no boxes or conduits filling with dust over time, leading to a hazard.

So, splice types should not matter since no splice should be arcing or sparking in 'normal operation'.

Keith Cress
kcress -

http://www.flaminsystems.com