Which figure is correct

hhsting

Senior Member
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? 20181227_204106.jpg

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texie

Senior Member
Location
Fort Collins, Colorado
Occupation
Electrician, Contractor, Inspector
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? View attachment 21915

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Figure 1 is correct.
 

jaggedben

Senior Member
...

Can solar experts from industry tell me which figure is correct installation in the attachment figure 1 or figure 2? View attachment 21915
No. :cool: 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.
 

jaggedben

Senior Member
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
 

pv_n00b

Senior Member
Location
CA, USA
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.
 

jaggedben

Senior Member
...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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