clearance of service conductors and non pressurized pipes

[bisonee]

I am doing a design in arkansas. Do to limited room we are looking at putting a transformer over a non pressurized storm sewer pipe. Is there and clearance requirments for that with respect to the pipe and electrical equipment including conductors in conduit. Unfortunetly this is not my design. It is a VE proposed by the contractor and approved by the owner.

 

[dpc]

I'm not aware of any NEC restrictions, other than the normal burial depth requirements.

I assume the same entity owns both the sewer line and the electrical equipment?

And I assume they've consider how they would deal with any necessary repairs to the sewer line after the transforme is installed.

I'd certainly recommend concrete encasement of the conduit in the vicinity of the sewer line and appropriate warning tape, etc.

 

[bisonee]

Thanks for the response. The sewer line under the transformer will be concrete pipe....everyelse it will be pvc. There is nothing in NEC. I am just not sure if there is local jurisdiction. I am having trouble finding anything online and unfortunetly right now the engineer at the utility company is out of town.

 

[BJC]

All non pressurized pipes can become pressurized under some circumstances. Do the What -ifs. What if a dead bird or a possum washes down the pipe, a bushel of leaves etc. Where does the water go?
Contractors and owners usually look just a little ahead of the next check they write and not much further.

 

[Electic]

NESC section 352 addresses this and gives general horizontal separation requirement between UG power lines and other utilities as 12" minimum.

But then the NESC allows less than 12" horizontal separation when "conditions require", with requirements for "mutual agreement between all parties, and adequate vertical separation to permit access to either system without disturbing the neighboring system.

I would do it if there is no seam in the pipe under the transformer, there was substantial vertical separation, and; if it is likely the sewer pipe will need access (for what ever reasons I cannot imagine) have some structure in place to support the transformer.

 

[dpc]

If the electrical conduit belongs to the utility, they will need to comply with NESC and may have their own rules that would trump any local codes, etc.