Planning electrical outlet in backyard orchard

Discussion in 'Electrical Forum discussion & Blog' started by Andy5400, Jun 29, 2020.

  1. Andy5400

    Andy5400 New Member

    Joined:
    Jun 29, 2020
    Location:
    Bethel, CT
    As a homeowner, I plan to dig a trench, 18 inches deep and 75 feet long, from my house to my orchard. I'd like to install all the services that I might need going forward, as long as I'm digging once!

    Important question: Can I put a 120VAC feed, a water line (1-inch poly, 60psi), and irrigation electrical wires (24VAC) in the same trench (i.e. separate conduits, in same trench)?

    From what I've learned so far: I plan to put the 120VAC in grey PVC 1-inch Sched 40 conduit, use 12AWG individual conductors with XHHW insulation, use 3 conductors (hot neutral ground), and protect with a 20A GFCI in the house ckt bkr panel. And use more substantial conduit, where the conduit rises vertically at the orchard. Then a watertight outlet box mounted on a vertical post. At the house I plan to go straight through the concrete foundation at 18 inches below grade, then put an electrical box on the inside basement wall to connect to house Romex. (Or is there a requirement that the conduit come out of the ground on the house exterior wall and go inside via an ell?)

    I plan to run a separate PVC conduit for the 24VAC irrigation electrical wires. Is it accurate that there are no NEC requirements about these 24VAC wires?

    Is it important to put sand and a warning tape in the trench, to warn against digging? Is this a requirement of the NEC or of local building inspectors?

    I want to learn about this and get smarter, before I talk with the town and get a permit.

    What else do I need to consider?
     
  2. drick

    drick In the Trades

    Joined:
    May 16, 2008
    Yup, not a problem.

    Your plan is ok as is, however I would think twice about drilling through the concrete foundation. If it leaks it can be a pain to fix.

    There are no requirements, but conduit will help protect the wires from critters. Also, if you need to add more conductors for additional valves later on you will have an easy way to accomplish it.

    The only way to know if your town has requirements beyond what is in the NEC is to ask your inspector. You can do that when you pull the permit. While I don't believe there is a requirement to use sand specifically, you do have to use clean fill over/around conduits. The warning tape is cheap insurance. Bury it 6" above the conduits.

    Consider installing 160 PSI poly. The big box stores do carry it and its more durable than the common 100 PSI pipe. Consider adding a spare 1" conduit. Cap both ends and bury it with everything else in the trench. One inch conduit is cheap and you never know what you might need it for.
     
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  4. Andy5400

    Andy5400 New Member

    Joined:
    Jun 29, 2020
    Location:
    Bethel, CT
    drick, thanks so much for your reply! I understand all of your comments.
     
  5. Onokai

    Onokai Member

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    Apr 19, 2012
    Location:
    Arcata,Ca
    I just did 650 feet of trenches-I put the electrical conduit in 1st on bottom-then about 2 inchs above the water line.(that ways you can reapair a leak. Conduit rarely fails. On your sand idea in theory its great but in practice all the tree roots go for the easy way and sand is like a magnet for them . Conduit and water pipes are tough (I use schedule 80 (NSF pipe) and dirt fill is just fine and over time it a bit less root filled.
    I also used tracer wire instead of tape but either will do.I had to locate all my previous buried servive from 1986 and thats why I went with tracer wire its easier to locate.
     
  6. Andy5400

    Andy5400 New Member

    Joined:
    Jun 29, 2020
    Location:
    Bethel, CT
    Onokai, thanks for your comments. Good point about sand and tree roots!
     
  7. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Joined:
    Sep 2, 2004
    Occupation:
    Retired Systems engineer for defense industry.
    Location:
    New England
    Consider running another hot wire that would let you create a second 120vac circuit using a shared neutral, or a 240vac one.

    If you think you'll maybe need to add a wire or replace one, you could run a pull string along with the wires.
     
  8. Andy5400

    Andy5400 New Member

    Joined:
    Jun 29, 2020
    Location:
    Bethel, CT
    Jim, thanks, yes it's all easier if done at the beginning.
     
  9. Onokai

    Onokai Member

    Joined:
    Apr 19, 2012
    Location:
    Arcata,Ca
    My other tip is put in larger condiut. Check into ordering whats called direct burial conduit. Electrical supply house can order it-it far cheaper than say schedule 40. I just used a bunch 1 1/2 inch -you cannot come out of ground with it (use schedule 40 or 80 for that)It thinner and more flexible -been using it for 40 years now. no issues
    pulling extra wire is always wise and use lots of wire lube if its a smaller conduit . Have ing a 110 volt curcuit is a plus beside the 220 one.You can use the same ground but you will need an extra nutral for that run
     
  10. wwhitney

    wwhitney Active Member

    Joined:
    Mar 17, 2019
    Location:
    Berkeley, CA
    Quick comment: the wiring depths listed in NEC Table 300.5 are cover depths, meaning the top of the conduit/cable must be at least that deep. So for 18", you'd need a 19" or 20" deep trench.

    Also, sounds like your installation would fall under Column 4, Row, 1 which only requires 12" cover depth.

    Cheers, Wayne
     
  11. Andy5400

    Andy5400 New Member

    Joined:
    Jun 29, 2020
    Location:
    Bethel, CT
    Onokai,
    "Direct burial conduit" is new to me! (Sure, I know about direct burial CABLE, UF-B, that goes in the ground without conduit. But not "direct burial conduit".) Are you referring to something like "Carlon 2 in. Non-Metallic Liquid Tight Conduit" (sold by the big box stores)?

    wwhitney,
    Thanks, I see your point. It does appear that the NEC allows 12" in my case, with just one 120VAC 20A leg and a GFCI breaker. I'll need to ask my town.
     
  12. wwhitney

    wwhitney Active Member

    Joined:
    Mar 17, 2019
    Location:
    Berkeley, CA
    As an alternative to Schedule 40 PVC conduit, there is also a thinner wall version that can only be used underground. But for 75' the cost savings wouldn't be much, so I don't see much upside for you.

    One argument for going for the full 18" cover would be if there's a significant chance you'd want more power out there later. And of course, since you're in CT, you'll want to be below the frost depth for the water line, which may be the controlling factor.

    Cheers, Wayne
     
  13. Onokai

    Onokai Member

    Joined:
    Apr 19, 2012
    Location:
    Arcata,Ca
    No thats not it-its not sold in any big box store. Its called DB-DUCT .It comes in 20 foot lengths with a connection bell at one end.Only thru an electrical wholesaler or like Platt Electric way cheaper than shedule 40-but come out of ground with shedule 40 no the db-duct. In terms of trench depth just find out your proper depth for your area and set the machine to that -no issues on that as well. Dig it deeper as you will add the other stuff on top. Put the power in first. If the inspector says no to water just have him sign off on the electrical and add the water after he is gone-just make sure you separate them so you can repair the water line if it fails. Electrical never fails unless dug up.The direct burial conduit comes in 1 inch and 1 1/2 inch maybe larger as well.Been using it forever-most suppliers have to order it but thats a few days at most.
     
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