lift station classification

Status
Not open for further replies.

hardworkingstiff

Senior Member
Location
Wilmington, NC
I've been told that an EE wrote the following about a sewer lift station.
Comments with regard to Septic pump comments.



1) g. ii. The interior of the wet well is classified Class 1,
Division 1. A sphere 3' in diameter from any vent opening is Class 1,
Division 1. A sphere between 3' & 5' from any vent opening is Class 1,
Division 2. If the wet well has a hatch, the area above the hatch & out
3' from the perimeter of the hatch & 18" high is Class 1, Division 2.



1) g. v. The control panel should be listed to UL 698A, Industrial
Control Panels Relating to Hazardous (Classified) Locations.

The job was installed (to the best of my knowledge from phone calls) with PVC conduit coming out of the lift station with the cords from the pumps and float switches going to the control box about 5' away from the well. Duct seal was used to seal the conduit. I've seen this method of wiring pass inspection before and I've seen it discussed on this site (I'm pretty sure) as the standard method for wiring a sewer lift station. The State EI turned the job down and wants sealoffs installed in the conduit.

Anyone run into this before?
 

Jlarson

Member
Location
AZ
Lose the hard conduit connection.

If the cords come into the panel I would pull them back out, then cut the PVC down below the panel so you have an air gap and bring each cord in through a cord grip. Put a KO seal on the old hole and you should be all good to go.

If you put seals in and the SO cord is chicoed in you will be hated by every operator and service electrician to follow that ever has to replace a switch or pump.
 

ericsherman37

Senior Member
Location
Oregon Coast
Yah. Helped do a brand new sewer plant and a couple lift station upgrades (in the same town) a few years ago. All the class 1 div 1 stuff was RMC and seal-offs basically everywhere within some arbitrary distance of any sewage tanks and ponds and wet wells and whatnot.

We do a fair amount of lift stations around here, and they all have seal-offs and Rigid Metal pipe. Check out 501.10(A)(1)(a) and (b). PVC only allowed encased in concrete or underground, with RMC finishing off the run where it emerges from grade.

PVC 'n duct seal ain't good enough :D
 

hardworkingstiff

Senior Member
Location
Wilmington, NC
Lose the hard conduit connection.

If the cords come into the panel I would pull them back out, then cut the PVC down below the panel so you have an air gap and bring each cord in through a cord grip. Put a KO seal on the old hole and you should be all good to go.

If you put seals in and the SO cord is chicoed in you will be hated by every operator and service electrician to follow that ever has to replace a switch or pump.


Wow, that's almost exactly (word for word) what I suggested to my GC friend that is in this situation.
 

hardworkingstiff

Senior Member
Location
Wilmington, NC
FYI, the state EI suggested they install a SS junction box below the control panel and install sealoff between the jb and panel, then bring the PVC from the wet well up into the bottom of the jb.

This way someone could cut the cord in the jb and replace a component without disturbing the conduit seal. :-? I could not understand the reasoning and wanted to call the EI, but the GC said no, he just wants to get out of this job. The EC on the job refused to wire it the suggested way and I told the GC I would not wire it that way either.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Lou, all I can say is if the health department mandates it then it must be. If the electrical inspector is in this demanding a sealoff it is probably because of the methane gases. In out area of NC they allow duct seal- I usually seal both ends.
 

hardworkingstiff

Senior Member
Location
Wilmington, NC
Lou, all I can say is if the health department mandates it then it must be. If the electrical inspector is in this demanding a sealoff it is probably because of the methane gases. In out area of NC they allow duct seal- I usually seal both ends.

Thanks Dennis. I think the air gap idea is the best approach with sealing the PVC conduit with duct seal. This way equipment can be replaced without damaging all cords in the conduit and the control cabinet won't be exposed to any gases.

I've wired a couple units with the duct seal and had them passed, I guess I was wrong those times (the EI too)?
 

Jlarson

Member
Location
AZ
Wow, that's almost exactly (word for word) what I suggested to my GC friend that is in this situation.

Ha ha, maybe you got it from that other forum, I posted the same thing there a while back.

FYI, the state EI suggested they install a SS junction box below the control panel and install sealoff between the jb and panel, then bring the PVC from the wet well up into the bottom of the jb.
This way someone could cut the cord in the jb and replace a component without disturbing the conduit seal.

That's just a stupid idea. EI's :roll:
 
Status
Not open for further replies.
Top