690.41(A)(6)

[tortuga]

Can anyone give me an example of a PV system that falls under 690.41(A)(6) that does not also fall under (A) 1-5?
In the 2017 NEC this read like :

PV systems that use other methods that accomplish equivalent system protection in accordance with 250.4(A) with
equipment listed and identified for the use

In the 2023 it reads like

Circuits protected by equipment listed and identified for the use

Thanks in advance.

 

[pv_n00b]

I've found that in a number of places in the code, this type of catch-all is put at the end of many lists of options. If someone develops a novel grounding system that satisfies 690.41(A) but does not fall under (1)-(5) it might be qualified under (6). I am not aware of any specific equipment that currently relies on (6).

 

[tortuga]

Would that not fall under (1) or (2) functionally grounded?

 

[jaggedben]

Would that not fall under (1) or (2) functionally grounded?

Not necessarily. I think it could theoretically apply to a solidly grounded system beyond the allowances of 690.41(B)(1).

 

[tortuga]

Not necessarily. I think it could theoretically apply to a solidly grounded system beyond the allowances of 690.41(B)(1).

Would that not be covered by (5)?
And that brings me to (5) why do we need permission to use a solidly grounded circuit? Are they prohibited somewhere else?

 

[don_resqcapt19]

Would that not be covered by (5)?
And that brings me to (5) why do we need permission to use a solidly grounded circuit? Are they prohibited somewhere else?

There is a few days left to try to fix that...the submission of PIs for the 2026 code ends at 5pm eastern 0n 9/7

 

[jaggedben]

Would that not be covered by (5)?
And that brings me to (5) why do we need permission to use a solidly grounded circuit? Are they prohibited somewhere else?

Solidly grounded systems using (5) are limited to two modules in parallel and not in or on buildings. In 690.41(B).

Solidly grounded systems of bigger size are not allowed because if a there's a ungrounded-to-ground fault in the remaining conductor then you have a short circuit with typically no device to stop it.

Conceivably maybe with (6) you can get a topology listed where there is a solidly grounded conductor but there's MLPE that detects faults and disconnects module leads from the module cells to provide GFDI. Or something. Can't think of any advantage to something like that. But to pv_noobs point it's basically a catchall that says if you can get another method listed you can do it.

 

[tortuga]

Thanks Ben for the explanation.
I think, as Part V is about grounding, 690.41(A) should be just defining 4 configurations like so:

1. Functionally grounded
2. Circuits not isolated from the inverter output circuit
3. Ungrounded
4. Solidly grounded

Then deal with any restrictions to those configurations in other sections like (B) and move wording like in (6) to somewhere else.
It seems to me like any of the configurations can be 2 wire or 3 wire so the # of wires is not defining a configuration either.