Exposed vs buried wiring

Steve961
Steve961 Solar Expert Posts: 93 ✭✭✭✭
in PV Installers Forum - NEC, Wiring, Installation #1
I am considering a pole mount for a couple of panels at my small cabin. The mount would only be about 4 feet away from the cabin, and I was wondering if it would be safe to run the wire directly into the attic rather than burying it? This would save me a considerable amount of length and allow me to use smaller wire - it's also easier than burying it.

My question has to do with safety, since there are no codes I have to meet where I am. I would be able to keep the wires at least 8 feet off the ground so nobody would walk into them. Are there any dangers to exposed wiring that would keep me from doing this?

Thanks.

Steve
· Share on Twitter

Comments

  • audredger
    audredger Solar Expert Posts: 272 ✭✭
    #2
    Re: Exposed vs buried wiring

    If you ran the wires overhead, you would want to protect them from UV exposure and squirrels. Squirrels and all rodents like wire insulation.
    · Share on Twitter
  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #3
    Re: Exposed vs buried wiring

    I'd at least put a J box/combiner at the pole side, so you just run the minimum # of wires, but running overhead wires is not a hard problem.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

    · Share on Twitter
  • Steve961
    Steve961 Solar Expert Posts: 93 ✭✭✭✭
    #4
    Re: Exposed vs buried wiring
    audredger wrote: »
    If you ran the wires overhead, you would want to protect them from UV exposure and squirrels. Squirrels and all rodents like wire insulation.

    Any recommendations on what to protect the wires with?

    Thanks.

    Steve
    · Share on Twitter
  • drees
    drees Solar Expert Posts: 482 ✭✭✭
    #5
    Re: Exposed vs buried wiring
    Steve961 wrote: »
    Any recommendations on what to protect the wires with?
    UV rated conduit, typically EMT or PVC with the appropriate rating.
    · Share on Twitter
  • newenergy
    newenergy Solar Expert Posts: 291 ✭✭✭✭✭✭
    #6
    Re: Exposed vs buried wiring

    It town I think it would be pretty crazy to run EMT or PVC through 4' of air and would just run the wires in the air attaching to strain relief, but out in the wilderness I guess flying conduit would be ok and would keep animals off the conductors.
    · Share on Twitter
  • audredger
    audredger Solar Expert Posts: 272 ✭✭
    #7
    Re: Exposed vs buried wiring

    Hold on... flying conduit? Conduit should be supported at both ends. Conduit supports the wire not the other way. If you run wires and no conduit, wire still need to be supported. Strain relief at both ends still stretches the wire. Run a steel cable then support the wires from it.
    · Share on Twitter
  • newenergy
    newenergy Solar Expert Posts: 291 ✭✭✭✭✭✭
    #8
    Re: Exposed vs buried wiring

    If you run conduit, yeah, the conduit would be supported at the end. 4' stretch and the conduit is still going to support itself and the wire.

    Yeah, in free air conductors should be wrapped around a guiding cable.

    By "flying" I just meant covering any span between structures, not unsupported.
    · Share on Twitter
  • audredger
    audredger Solar Expert Posts: 272 ✭✭
    #9
    Re: Exposed vs buried wiring

    Ok, the picture in my mind wasn't pretty..
    · Share on Twitter
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #10
    Re: Exposed vs buried wiring

    A cheap, easy solution is to run wire inside poly water pipe. Where we live, burying wire is not on option due to Canadian shield. I have run lots of wire directly on the ground, inside poly water pipe, and let the duff eventually bury them.

    I have also used it to protect wire from UV in the air.

    Tony
    · Share on Twitter
  • dwh
    dwh Solar Expert Posts: 1,341 ✭✭✭
    #11
    Re: Exposed vs buried wiring

    Running an overhead drop is not a problem, and normally does *not* require a "guide cable". There are tons of homes with overhead drops to a detached garage - and no guide/support cable for the conductors. Normally, the only issue is making sure it's high enough to provide clearance. When the conductors get big (heavy) enough (like a pole drop to a service entrance) or when it is a long distance, then support becomes an issue. A 4' drop is no big deal - as long as it is high enough above grade.

    For me, the first issue I see is that the pole will move. Depending on how much it moves, that could be an issue if the wires (even with a support cable) get pulled tight. Pole flexing is *definitely* an issue if conduit is used - ESPECIALLY if the conduit is secured at both ends.

    What I would do if it were me would be to run a LFMC (Liquid-tight Flexible Metallic Conduit) from the combiner box to the attic. I would secure both ends, but leave enough slack so that it won't get stretched tight and broken.

    The only problem there, is that normal "SealTight" type of conduit

    http://www.delikon.com/yf_706.html

    is also sometimes tasty to the little beasties, so I might consider something like:

    http://www.delikon.com/sm701.html

    which would also be stronger in the case of extreme pole flex.


    Probably though, I'd just go with SealTight and not worry about the overbraid until and unless the beasties became a problem.
    · Share on Twitter

Categories