Lift station classified area

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Tadco Tim

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Location
Palm Bay, FL
Got a lift station wet well that sticks out of the ground about 2.5'. The equipment rack is at grade level 2.5" below the top of the wet well, the duplex controller is in a nema 4x SS Hoffman cabinet and installed at 4' to the center of it, below it are the explosion proof seal offs and explosion proof termination cabinet. The entire rack sits off the edge of the well about 3'. The potential problem that the EE is checking on...Is the duplex controller in the hydrogen sulfide gas classified area? Most lift stations wet well lids are at grade level, so the 18" classified area is well below the duplex controller. Since the duplex controller is at the same level as the lid that also has a vent in it, does the duplex controller need to be raised to the 18" above the hazardous gas classified area?
 

rbalex

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Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
The basic classification rules are in NFPA 820, Standard for Fire Protection in Wastewater Treatment and Collection Facilities;
the Tables are similar to those in Article 514 and are both extensive and comprehensive. Without more details, I would be concerned with the vent.
 
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