Separately Derived Systems and 250.25 & 250.30(C)

[electrofelon]

I still think it's funny that for the 20+ years I've been doing PV people have been arguing over if the supply side PV disconnect is/is not a service disconnecting means, and if not should it be installed under the same requirements anyway. The closest the NEC has been to defining this is the 2023 705.11(D) which calls the PV disconnect a service disconnecting means and requires that it be installed as a service disconnecting means. And that was only put in the 2023 NEC to stave off a code war with the CMP that covers 230 who wanted the disconnect to be considered a service disconnecting means and was willing to act on it by adding language to 230. But now that war has been averted the 2026 705.11 will remove the language. Massive changes in the code from cycle to cycle, always good for safety.
Grounding of supply side PV disconnects was defined in 2020 by the addition of 250.25. That was undefined for way too long.

What they should have done is never created the concept of a "supply side connection". You already could do that using 230.40 exceptions. All they needed to do was tweak wording or provide an exception for the number of disconnects and grouping. They really made it silly and complicated.

 

[ggunn]

What they should have done is never created the concept of a "supply side connection". You already could do that using 230.40 exceptions. All they needed to do was tweak wording or provide an exception for the number of disconnects and grouping. They really made it silly and complicated.

Or, and I am going out on a limb here, maybe they could have drawn up 705.11 to describe, thoroughly, explicitly, and succinctly, how a supply side PV interconnection is to be constructed, with all the interlocking compliances to other sections of the code baked in. Yeah, I know, that's fantasyland thinking.

 

[jaggedben]

What they should have done is never created the concept of a "supply side connection". You already could do that using 230.40 exceptions. All they needed to do was tweak wording or provide an exception for the number of disconnects and grouping. They really made it silly and complicated.

Or, and I am going out on a limb here, maybe they could have drawn up 705.11 to describe, thoroughly, explicitly, and succinctly, how a supply side PV interconnection is to be constructed, with all the interlocking compliances to other sections of the code baked in. Yeah, I know, that's fantasyland thinking.

You guys mean how they finally worded 705.11 in the 2023 NEC? I think we got there. It only took 38 years.

 

[pv_n00b]

If you read the panel statement for FR 8568 there is no real change.

There was a lot going on internally behind the scenes and I have spoken to several CMP members on the subject. The real reasons are not going to go into the official panel statement. The politically acceptable reasons will. You can go back and look at the proposed language that was added to 230 in the 2023 first draft where the CMP for 230 put in their own requirements for a PV interconnection.

 

[pv_n00b]

You will find the added language in the 2023 first draft under a new article 231. This was removed when 705 was changed to what we see now. The new 231 was basically a copy of 705.11 with changes made to require the PV disconnect to be treated as a service disconnect.

 

[don_resqcapt19]

There was a lot going on internally behind the scenes and I have spoken to several CMP members on the subject. The real reasons are not going to go into the official panel statement. The politically acceptable reasons will. You can go back and look at the proposed language that was added to 230 in the 2023 first draft where the CMP for 230 put in their own requirements for a PV interconnection.

I was sitting in on the task group meeting when CMP 10 created new Article 231 Electric Power Sources Interconnected to an Electric Utility. This new article actually appears in the 2023 first draft report.
The chair of CMP 4 was also sitting in on that task group meeting and the discussion between the panel 4 chair and the CMP 10 members was very intense.

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