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Thread: Raceways with more than one voltage

  1. #1
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    Raceways with more than one voltage

    I am wondering if there is an exception for having more than 1 voltage pass through the same raceway without physical barriers. For example, under a string inverter, where the AC voltage and RS -485 and or DC circuits could all come into the trough and then be brought into the inverter through nipples.
    Jesse White



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    Is this a proposal for the 2020 NEC or did it get posted in the wrong topic?
    Moderator-Washington State
    Ancora Imparo

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    Once again, I think I posted in the wrong topic. Somehow it's very difficult to navigate this site from a mobile device.
    Jesse White



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    Quote Originally Posted by Jesse7623 View Post
    Once again, I think I posted in the wrong topic. Somehow it's very difficult to navigate this site from a mobile device.
    I moved it to the Solar sub-forum. I hope that's where you wanted it.
    Once in a while you get shown the light
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  5. #5
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    Quote Originally Posted by Jesse7623 View Post
    I am wondering if there is an exception for having more than 1 voltage pass through the same raceway without physical barriers. For example, under a string inverter, where the AC voltage and RS -485 and or DC circuits could all come into the trough and then be brought into the inverter through nipples.
    The code doesn't prohibit more than one voltage if all are under 600V, it just prohibits PV circuits, i.e. DC, from being mixed with anything else. So AC and RS-485 are fine in the same raceway as long as the wiring is all rated for the highest voltage. But your DC would have to be partitioned or run somewhere else. (Optimizer output circuits are a gray area.)

    I'm not aware of any exceptions.

  6. #6
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    Quote Originally Posted by jaggedben View Post
    The code doesn't prohibit more than one voltage if all are under 600V, it just prohibits PV circuits, i.e. DC, from being mixed with anything else. So AC and RS-485 are fine in the same raceway as long as the wiring is all rated for the highest voltage. But your DC would have to be partitioned or run somewhere else. (Optimizer output circuits are a gray area.)

    I'm not aware of any exceptions.
    Why does the 690.31 handbook commentary directly contradict the text of the NEC? And I know this isn't commentary left over from the previous edition, because that particular commentary didn't exist in NEC 2011.

    Text of NEC: "PV source circuits and PV output circuits shall not be contained in the same raceway [etc] as [...] other non-PV systems, or inverter output circuits, unless the conductors of different systems are separated by a partition."

    Commentary text: "Conductors directly related to a specific PV system, such as those in DC and AC output power circuits, are permitted in the same raceway as PV source and output conductors, provided that they meet the requirements of 690.31(B)(1) thru (B)(4) and 300.3(C)"


    Those requirements mentioned in the commentary indicate to identify and group, and 300.3(C) states that the voltage needs to be as large as the largest voltage system. But they do not directly indicate that you have to partition or build in separate wiring structures.

  7. #7
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    Quote Originally Posted by Carultch View Post
    Why does the 690.31 handbook commentary directly contradict the text of the NEC? And I know this isn't commentary left over from the previous edition, because that particular commentary didn't exist in NEC 2011.

    Text of NEC: "PV source circuits and PV output circuits shall not be contained in the same raceway [etc] as [...] other non-PV systems, or inverter output circuits, unless the conductors of different systems are separated by a partition."

    Commentary text: "Conductors directly related to a specific PV system, such as those in DC and AC output power circuits, are permitted in the same raceway as PV source and output conductors, provided that they meet the requirements of 690.31(B)(1) thru (B)(4) and 300.3(C)"
    I don't see the contradiction. The section to which the commentary refers ("... provided they meet...") is where the NEC text you quoted resides.

  8. #8
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    AC and RS-485 could occupy the same raceway only if the RS-485 is not classified as a limited power circuit but instead under a different non-chapter-3 article.

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    Quote Originally Posted by Carultch View Post
    Why does the 690.31 handbook commentary directly contradict the text of the NEC? And I know this isn't commentary left over from the previous edition, because that particular commentary didn't exist in NEC 2011.
    I don't know why, but the commentary is wrong, IMHO, unless the partition can be installed, which the commentary doesn't precisely refer to.

    Interesting that it's not left over from 2011, when the code could have been interpreted that way. The phase 'or inverter outputs' was added to the 2014 NEC. Before that one could argue that the inverter output isn't 'non-PV'. Maybe the person writing the commentary didn't notice that.

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    Thanks guys.
    Jesse White



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