Can anyone give me some guidance on NEC requirements around sewer (wastewater ) lift stations? Specifically, what are the dimensions for Class 1 Group D Div. 1 and 2? What are the requirements for sealing conduits leaving the sump area and terminating in a non-hazardous area?
Wastewater pumping stations
- Thread starter jpiercy
- Start date
- Status
- Location
- Illinois
- Occupation
- retired electrician
The NEC does not define the classified area, it only tells you how to make the installation based on the area classification drawings.
Don
Don
Classified locations
Classified locations
It seems many inspectors and contractors steer away from this topic but---
Wastewater pump stations (sewage and storm water) are classified under NFPA 820, and recognized as hazardous under the NEC. Many state and local regulations affirm this requirement. Wiring methods include the use of sealoffs on RMC but most common by exception is an open wiring method for these Class1 Division 1 Group D Locations. There are a couple of other ex-proof methods used in other installations (gas, ..) but for the most part sewage pump manufacturers do not support the installation of ex-proof fittings.
At first look, sealoffs are an easy solution but they are a huge haste when you need to replace the pump. If you want a jbox in the wet well it corrodes and personally - I never liked to have splices in the wet well because of the corrosive environment. I realized years ago in the field contractors tended to install an air gap by stubbing up sch80 PVC conduit from the wet well and leaving "open wiring" to cord grips in the bottom of the jbox/disconnect/panel.
Now my questions -
Has anyone had experience with this method of open wiring, and if so can you reference standards for the air gap or a sketch that emphasizes what the minimum requirements are. I have seen many of these installations, but am not sure what the minimum requirements are.
Also, what limits are placed on this wiring method? Can a screening be placed around the air gap to protect the cables from vandals /rodents and will it still meet the code requirements? I assume this installation would be then similar to a panel pedestal as marketed for the application (and those only have a single small screened vents in solid pedestals from the wet well)...
Thanks in advance.
Classified locations
It seems many inspectors and contractors steer away from this topic but---
Wastewater pump stations (sewage and storm water) are classified under NFPA 820, and recognized as hazardous under the NEC. Many state and local regulations affirm this requirement. Wiring methods include the use of sealoffs on RMC but most common by exception is an open wiring method for these Class1 Division 1 Group D Locations. There are a couple of other ex-proof methods used in other installations (gas, ..) but for the most part sewage pump manufacturers do not support the installation of ex-proof fittings.
At first look, sealoffs are an easy solution but they are a huge haste when you need to replace the pump. If you want a jbox in the wet well it corrodes and personally - I never liked to have splices in the wet well because of the corrosive environment. I realized years ago in the field contractors tended to install an air gap by stubbing up sch80 PVC conduit from the wet well and leaving "open wiring" to cord grips in the bottom of the jbox/disconnect/panel.
Now my questions -
Has anyone had experience with this method of open wiring, and if so can you reference standards for the air gap or a sketch that emphasizes what the minimum requirements are. I have seen many of these installations, but am not sure what the minimum requirements are.
Also, what limits are placed on this wiring method? Can a screening be placed around the air gap to protect the cables from vandals /rodents and will it still meet the code requirements? I assume this installation would be then similar to a panel pedestal as marketed for the application (and those only have a single small screened vents in solid pedestals from the wet well)...
Thanks in advance.
stickboy1375
Senior Member
- Location
- Litchfield, CT
http://www.libertypumps.com/data/tbProducts/65_jb120.pdf
Check this out... Not sure if you are doing a residential job or not
Check this out... Not sure if you are doing a residential job or not
As far as I see it - and unless I am missing something - Residential applications are designated by the referenced NFPA (under the EIBC) as Class 1 Division 2 Group D locations. Whereas Sanitary sewers (Domestic, commercial, and industrial) are designated as Class 1, Division 1, Group D locations. Both of these locations require sealoffs or other acceptable method under the NEC.
Looking at this product by Liberty, does this really comply with location requirements for the wiring methods? I do not believe it does since the installation is in continuous conduit to the jb from the wet well and the cable seal is only liquid tight. Hence my confusion on this matter - why is this product marketed for the application if it does not meet the location requirements or am i just confused on this issue?
Looking at this product by Liberty, does this really comply with location requirements for the wiring methods? I do not believe it does since the installation is in continuous conduit to the jb from the wet well and the cable seal is only liquid tight. Hence my confusion on this matter - why is this product marketed for the application if it does not meet the location requirements or am i just confused on this issue?
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
We run the pump cord to a j-box set next to the wetwell. There is a cast ep junction box where the cord is made up. From the cast jb there is a seal off and then RMC to the electrical panel. The advantage of this system is the motor connections are not in the wetwell.
The open wiring method is one that I've seen use, sometimes with a SS shround around the wires.
The open wiring method is one that I've seen use, sometimes with a SS shround around the wires.
- Status