Mike Dolt Enterprises
Mike Dolt Enterprises
User: Hoyt, Location: Northern illinois
Asked on: Tuesday, April 5, 2011 at 4:07 pm EDT
Answered on: Tuesday, May 14, 2024 at 3:48 am EDT
Question: Attempting to determine the classification of an area and to what extent, if any, the classified area should extend.Existing property is what I would consider a Bulk Storage Plant per the NEC 515.2.Within this property we have a building that has a basement level 4? below grade and 4? above grade. At this basement level a mix of gas and water has flooded the level. The water/gas mix has been removed and a company was hired to install well pumps (pneumatic) in the floor to extract the ground water from below the floor and pump the water/gas mix from the basement level to another building. The fluids are then separated, etc. A cleanup effort/system.A ventilation fan has been installed to extract vapors off the concrete floor and discharge to the exterior.The well pumps system (6 total pumps) were installed as Class I, Div 2?. But existing lighting wiring is present (very old) and installed as unclassified wiring within the space. (This well pump system has not started yet?. Do to the existing wiring and questioning about the total space classification).We have been asked to review the space and process, then determine what classification the space is and to what extent if any.It is my opinion, per NEC 500.5 (B)(2) the space is Class I, Div.2. What I have not been able to determine is if the entire basement level should be classified?. or set dimensions around the well pump system should only be classified.NEC Table 515.3 (For Bulk Storage Plants) gives set dimensions of the classified areas? but I do not see any ?Locations? that would reflect what situation we have in this basement.
Classified Area Determination
Based on the provided information, the basement level can be classified as a Class I, Division 2 hazardous area according to NEC 500.5(B)(2). The presence of gasoline vapors (a flammable liquid) and the potential for ignition sources (electrical equipment and ventilation fan) create a hazardous location.
Extent of Classified Area
The extent of the classified area should be determined by considering the following factors: Source of flammable vapors
The primary source of flammable vapors is the groundwater/gas mixture being pumped from the floor. The area around the well pumps where the vapors are most concentrated should be classified.
Ventilation
The ventilation fan helps to remove vapors from the space. The area where the fan draws air from should be considered as a potential classified area.
Physical barriers
Walls, doors, and other physical barriers can help to limit the spread of vapors. The presence of such barriers should be considered when determining the extent of the classified area.
Recommended Approach
To determine the extent of the classified area, the following steps are recommended:1. Identify the vapor source
Determine the exact location of the well pumps and the area where the groundwater/gas mixture is being extracted.2.
Assess ventilation
Evaluate the location of the ventilation fan and consider the direction of air movement.3.
Consider barriers
Identify any walls, doors, or other physical barriers that could limit the spread of vapors.Based on these factors, it is likely that the classified area should extend: Around the well pumps and the area where the vapors are being extracted In the direction of air movement from the ventilation fan Up to the nearest physical barrier
Additional Considerations The unclassified lighting wiring present in the space should be removed or replaced with classified wiring. The well pump system should not be operated until the classified area is properly designated and all appropriate safeguards are in place.* Regular inspections and maintenance should be performed to ensure that the classified area remains safe. Flag for review