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Thread: PV conductor transition from PV cable to THWN-2

  1. #11
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    Quote Originally Posted by Designer69 View Post
    Each string must have it's own individual ocpd? So the combiner box has a fuse for each string? Is this this a code requirement somewhere?


    I understand there is only one DC ocpd at the solaredge inverter.
    In the 2014 NEC, see 690.9(A) Exception (b). With normal DC strings this usually means that when combining three or more PV source circuits (strings), each string must be individually fused. This is to protect a faulted string from being backfed by the other unfaulted strings. With optimizers, it's a bit different, and SolarEdge has released white paper reports that state that combining more than two strings does not necessitate fusing them, but some AHJ's will not accept this as proof since the papers were not written by an independent testing agency.

    SolarEdge inverters with a single DC input (or two) have no DC OCPD at all, only a switch.

  2. #12
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    Whoever designed it made a simple error. Bounce it back with a comment that both sides should be six current carrying conductors and an EGC. No need for everyone to get all wound up over this.

    Now for real fun let's debate if the PV conductors are really in "free air" in the array as it states. There has never been a general definition in the NEC for what it means for a conductor to be in free air, although it looks like the 2020 NEC will have it.

  3. #13
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    Quote Originally Posted by Designer69 View Post
    I am reviewing this project and have a question about the cables transitioning from PV cable to THWN-2.

    they show "quantity 3" PV cables to transition JB but "quantity 1" THWN-2 cables from JB to inverter.

    Shouldn't it also be "quantity 3" THWN-2 cables from JB to inverter?

    Please see pic for better info and let me know how you interpret it..

    pic: https://ibb.co/tMYJMt9

    Thank You
    To me it looks like the "Qty 1" is for number of conduits. 1 conduit from JB to inverter that has 6 current carrying conductors running in it (5th column in the table says 6 for # of current carrying conductors).

    Thank you

  4. #14
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    Quote Originally Posted by Electrical PE View Post
    To me it looks like the "Qty 1" is for number of conduits. 1 conduit from JB to inverter that has 6 current carrying conductors running in it (5th column in the table says 6 for # of current carrying conductors).

    Thank you
    Lol you're right. Although, the '3' still doesn't make compete sense for the PV wire, as that's the number of circuits not conduits. They probably should have put NA there.

  5. #15
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    Quote Originally Posted by jaggedben View Post
    Lol you're right. Although, the '3' still doesn't make compete sense for the PV wire, as that's the number of circuits not conduits. They probably should have put NA there.
    I would still bounce it with a comment. It's poorly documented and two pages of comments here on the subject show it's unclear.

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