What is the perimeter of Class 1 div 1 area, NEC section B.1.2

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fandi

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Electrical Engineer
Hello all,
I'm installing disc. sw and vfd for a new cooling tower in an outdoor location. There's a big long white propane tank 5 ft away (still outdoors). A chain fence separate the tank and the cooling tower+elec equipment. It seems to me that flammable gas may exist because of leakage. Can I install the elec equipment behind the cooling tower so that they're hidden from the tank and therefore the elec equipment doesn't have to be classified?
Thanks a lot.
 
Please review your reference; I have no idea what "NEC section B.1.2" is.

That said, depending on the processes involved, cooling towers themselves are often considered sources.
 
rbalex said:
Please review your reference; I have no idea what "NEC section B.1.2" is.

That said, depending on the processes involved, cooling towers themselves are often considered sources.
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Sorry, it's Art. 500.5.B.1.2 aka definition of Class I Div. 1. but I thought Cooling Towers are not considered hazardous locations other than the electrical equipment shall be in Nema 4X enclosures?
Thanks, Bob.
 
As I mentioned, it depends on the processes involved. A cooling tower serving shell and tube heat exchangers often receive flammable products that have leaked from the process tubes. See API RP500 Section 9.2.4 / Figure 28 for example.

You really need someone that is familiar with the whole process design to determine a proper electrical classification document. [Section 500.4(A)]
 
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