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Thread: Which figure is correct

  1. #1
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    Which figure is correct

    Figure 1 has neutral to ground bond AC PV disconnect with line side tap from service disco. Figire 2 has NO neutral to ground bond AC PV disconnect with line side tap from service disco. Both figures have GEC to buidling system ground or ground rod.

    Can solar experts from industry tell me which figure is correct installation in the attachment figure 1 or figure 2? Name:  20181227_204106.jpg
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  2. #2
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    Quote Originally Posted by hhsting View Post
    Figure 1 has neutral to ground bond AC PV disconnect with line side tap from service disco. Figire 2 has NO neutral to ground bond AC PV disconnect with line side tap from service disco. Both figures have GEC to buidling system ground or ground rod.

    Can solar experts from industry tell me which figure is correct installation in the attachment figure 1 or figure 2? Name:  20181227_204106.jpg
Views: 163
Size:  19.3 KB

    Sent from my SM-G935U using Tapatalk
    Figure 1 is correct.

  3. #3
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    Quote Originally Posted by hhsting View Post
    ...

    Can solar experts from industry tell me which figure is correct installation in the attachment figure 1 or figure 2? Name:  20181227_204106.jpg
Views: 163
Size:  19.3 KB
    No. Ask your AHJ.

    Figure 1 would be correct if your AHJ believes or accepts that the PV disco is an additional service disconnect and should he treated exactly as such. But your AHJ may precisely disagree that it's a service disconnect. The GEC part of figure 2 is unlikely to be correct if your AHJ says it's not a service disconnect. You may need no additional GEC, or your AHJ might even require something as silly as a separate grounding electrode system, per comments by ggunn elsewhere in this forum.

    Note that when you throw grounding and bonding together in the same question, there are more than the two answers your figures show.

    2020 NEC will likely finally tell us to bond neutral in the PV disco, if the first draft language survives.

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    I found an old post of mine that summarizes the arguments for and against considering the additional PV disconnect a service disconnect. (BTW, the comment at bottom about the 2017 didn't really pan out.)

    Like texie, I am biased towards considering Figure 1 correct. But until the 2020 NEC comes out things will remain quite 'interpretable' with plenty of arguments one way or the other.

    BTW, in case you didn't notice we have two threads on pretty much the same subject right now. See http://forums.mikeholt.com/showthread.php?t=195455

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    If installing without the neutral to ground bond in the disconnect an EGC is run back to the ground busbar in the service equipment. A GEC is only used if the disconnect has a neutral to ground bond since a GEC connects that specific point directly to a grounding electrode system.

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    Quote Originally Posted by pv_n00b View Post
    ...A GEC is only used if the disconnect has a neutral to ground bond since a GEC connects that specific point directly to a grounding electrode system.
    Strictly speaking, the NEC does not require a GEC to be terminated in the disconnect. It may ground the neutral at a single point somewhere upstream.

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    Quote Originally Posted by jaggedben View Post
    Strictly speaking, the NEC does not require a GEC to be terminated in the disconnect. It may ground the neutral at a single point somewhere upstream.
    Strictly speaking, the GEC does not ground the neutral.

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