RIE Building Code Questions

[NotreDave]

All,
Good afternoon. Can someone help me out with the NEC or NFPA codes regarding equipment (power panels, ATS switch, fluorescent lighting, receptacles, junction box) that are going to be installed in a RIE (Remote Instrument Enclosure) building. The building will be 15' x 12' (reference) and will be set in a Class 1, Div. 2 area of a chemical plant. Does the enclosures, etc..have to meet Class 1, Div. 1 rating? The building will not be pressurized. Does a building that is not pressurized in a Class 1, Div. 2 environment get a Class 1, Div. 1 rating automatically? Please share some knowledge for me. I would really appreciate anything that I can read to understand this.
Thank you in advance,
David

 

[gadfly56]

All,
Good afternoon. Can someone help me out with the NEC or NFPA codes regarding equipment (power panels, ATS switch, fluorescent lighting, receptacles, junction box) that are going to be installed in a RIE (Remote Instrument Enclosure) building. The building will be 15' x 12' (reference) and will be set in a Class 1, Div. 2 area of a chemical plant. Does the enclosures, etc..have to meet Class 1, Div. 1 rating? The building will not be pressurized. Does a building that is not pressurized in a Class 1, Div. 2 environment get a Class 1, Div. 1 rating automatically? Please share some knowledge for me. I would really appreciate anything that I can read to understand this.
Thank you in advance,
David

At worst I would think that the enclosures will have to meet Class I Div 2. I can't think of any reason they would have to meet the more severe standard. I would also think that if you set up proper "Z" purging you might save a lot of coin, depending on how many enclosures you have and how large they are.

That said, is the area the building sits in really Class I Div 2? This usually depends on the proximity of the building to the hazard, like an LNG compressor skid, for example. I suppose if there is a 6" N-heptane line running next to the building that would do it, but it might be worth another look to be sure someone didn't just get lazy with the classification map.

 

[jumper]

Moved to Hazardous Locations forum.

 

[rbalex]

You're going at it a bit backwards – but no big deal. You need to determine the room's classification first and then determine the equipment's requirements.

Pressurizing is not necessary; however, the building is almost certainly Division 2 with or without ventilation. Division 1 is unlikely unless some part of the processes are conducted internal to the building. This would include process sampling.

Power panels, the ATS, and receptacles need to be suitable for Division 1. Luminares will need to be specifically identifed for Division 2. If only terminals are in the junction boxes, ordinary location enclosures are acceptable.

Depending on how readily available a source of "clean air" is, Type Z pressurization could be cost effective. See NFPA 496.