Separate conduit - NEC interpretation

ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
I am working on a system that will have 30 SMA inverters and 1062 modules. Does each inverter have to have its own unshared conduit from its PV array and to the AC combiner?

Please hold your questions about why it's being done this way and not with a central inverter. If I could, I would. :cry:

Sorry for posting in two different subforums; I realized belatedly that this is the one it should have been in. Mods, feel free to delete the other one.

Comments

  • Solar GuppySolar Guppy Solar Expert Posts: 1,962 ✭✭✭
    Re: Separate conduit - NEC interpretation

    There is no NEC requirement on either DC or AC being single runs, its mixing AC and DC that's frowned upon.

    The Fill factor will be what limits the number of wires per conduit and its to make sure the wire is within its rated temperature.
  • realdealrealdeal Registered Users Posts: 4
    Re: Separate conduit - NEC interpretation

    You should purchase the "Understanding NEC requirements Photovoltaic Sysems" book by Mike Holt, there is direct reference to code and illustrated diagrams and pictures. There is a direct reference to your question. Bascically what i gather is that as long as you keep the wires bundle together (zip ties) then you can have AC and DC wires in the same raceway. As long as they are totally independent of non-pv system wiring. My interpretation,

    Mixing conductors of different systems 300.3(C) note-2

    Grouping- Where the conductors of more than one PV system occupy the same junction box or raceway with a removable cover, the AC and DC conductors must be grouped together by cable ties and at intervals that do not exceed 6 ft.

    The book is priceless!!!!!!!
  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: Separate conduit - NEC interpretation

    So as long as both the AC and DC cables are connected to, or used with a PV system in one way or another, and if more than one PV system, as long as the cables from the different PV systems are cable-tied together every 6 feet or less, it's OK to have them all in the same conduit? Just making sure I understand it.
    Gotta wonder how long before they come up with new ideas. Man it's hard to keep up with them!
  • BB.BB. Super Moderators, Administrators Posts: 28,990 admin
    Re: Separate conduit - NEC interpretation

    I think the bundling with ties is only for raceways with removable covers--or probably at the end of the runs where they enter into distribution/breaker boxes (removable covers).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Separate conduit - NEC interpretation
    BB. wrote: »
    I think the bundling with ties is only for raceways with removable covers--or probably at the end of the runs where they enter into distribution/breaker boxes (removable covers).

    -Bill

    Oui.

    Can't imagine trying to zip wires together and then feed them through conduit. :confused:

    See how clear NEC regs are? One rule; three interpretations. So far. :roll:
  • BB.BB. Super Moderators, Administrators Posts: 28,990 admin
    Re: Separate conduit - NEC interpretation

    With NEC you have to watch out for some of the other rules on sharing conduit... For example, as I recall, say you have some AC wiring and want to run signal wiring (computer, 24 volt, etc.). All wiring has to be rated to the "worst case" case wiring in the shared conduit... So, if your AC wiring requires 600 VAC rated THHN (or whatever), then the 24 volt/computer Cat5 cabling would also need to be rated to 600 VAC/THHN too...

    You could not mix low voltage insulation (based on circuit requirements) with high voltage insulation in the same conduit.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Separate conduit - NEC interpretation

    Thanks for the replies, but I wasn't asking about sharing conduit between DC and AC runs for the same system. I was asking if I can share conduit for DC runs between different systems. I think that the answer is yes, I can.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Separate conduit - NEC interpretation
    ggunn wrote: »
    Thanks for the replies, but I wasn't asking about sharing conduit between DC and AC runs for the same system. I was asking if I can share conduit for DC runs between different systems. I think that the answer is yes, I can.

    That's what Solar Guppy said in the first reply; they just want DC and AC separated, it doesn't matter how many conductors/circuits in the conduit as long as they're the same type.

    Sorry about the side-tracked responses: lateral thinking happens. :roll:
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