Class 2, Div. 1 install questions

[JoeSparky1]

I have been given the task of quoting a controls system for Class 2, Div. 1, Group G.

502.1 states exp. proof equip. and wiring shall not be required and shall not be acceptable in Class2 locations unless it is identified for those locations.
The control panel will be outside on the top of a grain elevator. NEMA 4 in addition to 7 and/or 9 (not sure which). Do the components INSIDE the box have to be rated for the environment or just the conduit and box.

The components inside the box will be wired to field devices inside the grain bin where the dust is present (div.1 location). The enclosure itself is mounted in a non hazardous location.

I am confused~if it is not required does that mean I don't have use it or what.

 

[weressl]

I have been given the task of quoting a controls system for Class 2, Div. 1, Group G.

502.1 states exp. proof equip. and wiring shall not be required and shall not be acceptable in Class2 locations unless it is identified for those locations.
The control panel will be outside on the top of a grain elevator. NEMA 4 in addition to 7 and/or 9 (not sure which). Do the components INSIDE the box have to be rated for the environment or just the conduit and box.

The components inside the box will be wired to field devices inside the grain bin where the dust is present (div.1 location). The enclosure itself is mounted in a non hazardous location.

I am confused~if it is not required does that mean I don't have use it or what.

Only the box has to be suitable for the installation.

 

[rbalex]

I believe you are citing the 2002 NEC.

?Explosionproof Apparatus? is a Class I, protection technique. [See Section 500.7(A)] When applied to enclosures only it is typically ?NEMA 7.? Many people erroneously assume that if a protection technique is suitable for Class I, it is also suitable for Class II.

Additionally, even in Class II, Division 1 not all enclosures must be ?Dust Ignitionproof? or ?NEMA 9? [Section 500.7(B)]. ?Dusttight? (NEMA Types 3,3S, 5, 12, 12K, or 13) may be acceptable in Class II, Division 1 depending on the application. Note: a box only marked "NEMA 4" is not ?dusttight?

OF course, many enclosures have multiple markings so you have to see that the appropriate markings exist.

The equipment inside the enclose do not require specific markings for Class II, if the other wiring methods required by 502.4(A)(1) are applied.

 

[JoeSparky1]

Are there any other documents or books that address the general installation practices for this type of thing? I can tell already that the moderators in this forum know more than most people ever will about these issues so the input is GREATLY appreciated.