Underground service and circuits

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Electriman

Senior Member
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TX
Greetings,

I am designing underground service and circuits for some projects. NEC does allow direct burial, PVC conduit and duct banks. Sometimes, I have to run wires a couple hundred feet in the streets and sidewalks before I get to the project location. I am thinking to use PVC SCH 80 conduit and bury it 24" below the grade. I don't want to be over design and at the same time conservative. I was wondering if you had similar experience and what you did.

Thanks in advance for sharing your experience and expertise.
 
Electriman said:
I am designing underground service and circuits for some projects. NEC does allow direct burial, PVC conduit and duct banks. Sometimes, I have to run wires a couple hundred feet in the streets and sidewalks before I get to the project location. I am thinking to use PVC SCH 80 conduit and bury it 24" below the grade. I don't want to be over design and at the same time conservative. I was wondering if you had similar experience and what you did.
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Over engineering or designing would not be a violation, (codes are minimum requirements) but if bidding job it may effect your winning job, I too would be inclined to use the heavier conduit under street and walkway (and may be required under certain circumstances) simply because of a "more than likely state" it would be re-excavated in the future and would provide a little more protection. But if you do, make sure you check fill for the 80, it has a smaller ID than schedule 40. And don't forget marking tracing tape, I know I appreciate it when I'm excavating in vicinity of buried lines.
24" is minimum depth when under driveway, not sure under public roadway that would regularly carry a much larger load, also gets much more reconstruction and regrading than a driveway, I could see that requiring a deeper depth but not sure.
 
I would first check with whatever authority owns the roads and sidewalks. They may have specifications regarding materials and depth.
I have been told on a job or two that we will be 10’ under the road on road bores by the state.
Had a job in town to bury the UG cable that had been strung overhead for years. The city wanted all conductor installed in pipe and buried a minimum of 42”.
 
Consider using 1 sack concrete mix as a slurry to encase the conduits. And can add red dye. Marking tape can help some, but I have seen the tape and conduit taken out in one bite by an excavator. Need good locates and record drawings
 
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