Subfloor classified area

[lexkyphil]

I have a natural gas compressor building that has a 5' deep subfloor area with open grating as the deck above. The building is power ventilated to 6 air changes per hour to keep it class I, div II. There is air being introduced below the floor at a high rate. We are using separate cable trays with 13.2kV MV105cable, various 120-480 power cables and control cables, all type TC, per 501.10 (B)(6). Is this area still to be classified as Division I? If so, I have to use ITC-HL or MC-HL. Would like to avoid using a different cable type. What are your thoughts?

 

[petersonra]

My first thought is to avoid running the cables in the pit.

 

[rbalex]

What standard is being used as the basis for classification? For the process you are describing the NEC alone is inadequate. You will probably want to review AGA XF0277.

 

[lexkyphil]

Gas codes

Gas codes

We did go back to AGA-XFO277 and RP500, which applies to this facility since it is classified as a transportation facility. It allows us to rate the grating deck underfloor area as Div II, since it is adjacent and ventilated. Thanks for the tip!