grain elevator wiring

[Garfields]

I would like to learn more about wiring methods required in a grain elevator. There are portions that are in a building with dust and portions outdoors. Is there a book someone could recommend on the subject?

 

[rbalex]

... Is there a book someone could recommend on the subject?

I've said in other topics and posts that classified locations isn't rocket science but it isn't quite trivial either. In this case, the "book" you referred to is the NEC, Articles 500 and 502 supplemented with NFPA 499, Recommended Practice for the Classification of Combustible Dusts and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas.

It is essential that the classified locations be properly documented as required by Section 500.4(A). NFPA 499 is one of the Reference Standards listed in Section 500.4(B) FPN/INs.

Once proper classifications have been established, suitable wiring methods for the classified locations can be selected directly from Section 502.10.

For Class II, sealing is not too complicated [502.15], just be careful to identify enclosures that are required to be dust-ignitionproof. The requirements for Divisions 1 and 2 are virtually identical in Class II.

NOTE: This statement may change with the 2017 NEC where "dust-ignitionproof" may become a somewhat obsolete term.
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Grounding and bonding may present a few challenges [502.30]; however, most ordinary standard practices are acceptable. Again, Divisions 1 and 2 are virtually identical in Class II.

 

[kwired]

Outdoors generally not classified, someone will disagree but will probably have something specific that maybe does create a hazardous location.

NEMA 3R still not a good idea in higher dust concentration areas as it finds a way into 3R enclosures, you want gasketed enclosures.

Indoors, housekeeping practices can make some difference between division 1 and division 2, but in general most areas are division 1 unless you are qualified (and willing to take on liablilty) to call them division 2.


Another thing that is outside the scope of hazard locations but is a common problem I see a lot is arranging raceways to drain condensation - it will happen.

 

[Garfields]

Outdoors generally not classified, someone will disagree but will probably have something specific that maybe does create a hazardous location.

NEMA 3R still not a good idea in higher dust concentration areas as it finds a way into 3R enclosures, you want gasketed enclosures.

Indoors, housekeeping practices can make some difference between division 1 and division 2, but in general most areas are division 1 unless you are qualified (and willing to take on liablilty) to call them division 2.


Another thing that is outside the scope of hazard locations but is a common problem I see a lot is arranging raceways to drain condensation - it will happen.

Normally the gasketed enclosures we work with are galvanized nema 4x and nema 12 with the piano hinge and in an underground tunnel they seem to seize up. Is there an enclosure with the gasket and the lift off lid? Also where is the condensate supposed to drop out if you are using sealed boxes? With a 3r it can drip out.

 

[kwired]

Normally the gasketed enclosures we work with are galvanized nema 4x and nema 12 with the piano hinge and in an underground tunnel they seem to seize up. Is there an enclosure with the gasket and the lift off lid? Also where is the condensate supposed to drop out if you are using sealed boxes? With a 3r it can drip out.

NEMA 4/12 with weep holes essentially becomes a 3R but is better sealed then a 3R without gasketed doors.

Underground tunnel may be worth considering stainless or fiberglass enclosures.