RIE skid mounted building

[NotreDave]

All,
I need your help. I am getting contradicting answers on this question. There will be a RIE (Remote Instrument Enclosure) skid mounted building, 15' x 12' that is going in a Class 1, Div. 2 environment in plant site. One engineer is telling me that all equipment (power panels, receptacles, lighting) to be mounted inside has to meet Class 1, Div. 1 criteria. Another engineer is telling me that since the area class is Class 1, Div. 2, then the equipment inside must meet that classification. Which one is correct? Whoever is right doesn't concern me because I would like to know how, why and where I can find out this information for myself. If someone can direct me to a code in the code book or NFPA, I would be glad to read about it. Also, this building will be elevated on 24" piers, if that makes a difference. I really would like some feedback pretty quick as I am checking a RIE package and finding things like power panel enclosures, receptacles that meet Class 1, Div. 1 and lighting, air conditioner, 2 Honeywell HPM cabinets that meet Class 1, Div. 2. PLEASE HELP ME....
Thank you in advance,
David

 

[petersonra]

I don't think it is up to you to decide. Someone will have to put their name (and maybe their PE stamp) on a document stating what the classification is inside this room. That is the guy who decides.

Most of these kind of rooms I have seen are pressurized so they are effectively unclassified inside.

I am not sure how it would get from division 2 outside to division 1 inside unless there is some vapor being released inside the room that is flammable.

In any case there is no difference between power panels and anything else that has potentially arcing contacts for a CID1 area and a CID2 area.

ETA: I wonder if they are putting it on stilts to get above the classified area. It is not like the classified area extends above the floor indefinitely.

 

[north star]

@ ~ @


NotreDave,

I agree with **petersonra** !......Any design documents should have
a Registered Design Professional seal & signature on them.......The
documents "should" provide the Standards to which the project is
being designed, including which classification is being referenced
and designed to.


@ ~ @

 

[NotreDave]

The building will not be pressurized.

 

[rbalex]

I started answering your question here.

To finish:

Start with NEC Section 501.10(B)(4) and follow its cross references. Add Sections 501.130(B) and 501.145.

 

[rbalex]

I guess I should add a few more comments:

Section 500.4(A) requires classified locations to be properly documented. It does NOT say that it must be done by a professional engineer. While it is my preference too, over half the members on Code Making Panel 14 that are engineers are not PEs. In my opinion, those CMP14 engineers are still quite qualified to classify locations; but most engineers, PE or not, aren't. Actually, most electrical building inspectors, aren't qualified to classify a location either. A few Fire Marshalls are. Insurance inspectors, because they have money on the line, are pretty good.

Section 500.8 is also a critical reference for understanding equipment requirements, especially approval requirements, [500.8(B)] and marking requirements [500.8(C)]. Reading, studying and understanding the whole Section is still worth it if you want to know what you're doing. There are several surprises for the uninitiated.

petersonra's comment about the enclosure being raised is well taken. It is quite possible the interior didn't need to be classified at all. But since it apparently has been, the installation must nevertheless be consistent with it. Raising it often adds additional boundary seals in such cases, but not always. There can be some judiciously located enclosure seals for internal equipment that do "double duty".

 

[NotreDave]

Thank you all very much to you who have responded!