Installing Overfill Protectio Panel In Classified Area of The Tank

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DS EE

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Orlando, FL USA
I've ways thought that control and alarm panels were to be installed outside of classified areas. I have observed many panels installed within the 10' classified area around a fuel tank; most commonly the independent overfill protection panels. I know the sensors are intrinsically safe but the panels are NEMA 4X enclosures and have 120V power supplies and various relays and 120V components inside that could potentially create a spark. Even with seal offs on the conduits vapors can enter a 4X enclosure so I'm not sure why this is allowed. Can anyone explain why this is allowed in so many places or what I'm missing in my interpretation of the NEC for installing panels in classified areas. Thanks
 
is it a division 2 area? if so the requirements are pretty relaxed compared to a division 1 area. a lot of times you can put general purpose components in a division 2 area. not normal relays though, but you can use relays with sealed contacts.
 
petersonra said:
is it a division 2 area? if so the requirements are pretty relaxed compared to a division 1 area. a lot of times you can put general purpose components in a division 2 area. not normal relays though, but you can use relays with sealed contacts.
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Yes, open areas with 1 or a few 8k to 30k gallon tanks normally. I must have missed or miss interpreted the description of what is allowed where in division 1 verses division 2 areas.
 
For Division 2, I would suggest seeing Section 501.10(B)(4). It basically cross references to where explosionproof enclosures are required in Division 2. Where an enclosure is not required to be explosionproof, a seal is useless for enclosure protection. This does not mean an explosionproof enclosure cannot be used, rather it and any associated seals aren't necessary in the particular application.
 
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