Still confused on 690.12

[electrofelon]

Say we have a backfed breaker interconnection inside the house. Inverter mounted at a ground Mount array. AC inverter output circuit running from the interior panel to the ground Mount array. Do I need to disconnect at the house? Looking at the new exception in the 2023, it doesnt seem necessary, since the inverter would be outside the array boundary so isn't it covered without the exception? But then it appears that the conductors need to terminate ON the building, so isn't that essentially saying yes rapid shut down applies?

 

[tortuga]

Rapid shutdown is the AFCI of the solar industry.

 

[wwhitney]

A few comments:

1) Seems like 225.31(A) requires a disconnect for the feeder from the remote inverter to the house, nearest the point of entry of the feeder, either inside or outside.

2) Is the supporting means of the inverter a "structure"? If so, it requires a 225.31(A) disconnecting means.

3) Some disconnect between the utility and the inverter is the PV System disconnect required by 690.13. Conductors on the utility side of that disconnect are not PV System conductors, per the definition of PV System. So if you have an AC disconnect near the inverter, you can label it as the PV System disconnect, and then conductors from the house to that AC disconnect are not PV System conductors, and hence not controlled conductors.

4) Regardless, if your array is ground mount, and the inverter is outside the array boundary, then the inverter output circuit is not a controlled conductor per 690.12(A). The exception to 690.12(A) only relieves some conductors from being controlled conductors, it doesn't make any conductors controlled conductors.

Cheers, Wayne

 

[electrofelon]

A few comments:

1) Seems like 225.31(A) requires a disconnect for the feeder from the remote inverter to the house, nearest the point of entry of the feeder, either inside or outside.

2) Is the supporting means of the inverter a "structure"? If so, it requires a 225.31(A) disconnecting means.

3) Some disconnect between the utility and the inverter is the PV System disconnect required by 690.13. Conductors on the utility side of that disconnect are not PV System conductors, per the definition of PV System. So if you have an AC disconnect near the inverter, you can label it as the PV System disconnect, and then conductors from the house to that AC disconnect are not PV System conductors, and hence not controlled conductors.

4) Regardless, if your array is ground mount, and the inverter is outside the array boundary, then the inverter output circuit is not a controlled conductor per 690.12(A). The exception to 690.12(A) only relieves some conductors from being controlled conductors, it doesn't make any conductors controlled conductors.

Cheers, Wayne

Thanks for the thoughts Wayne.

1) I dont think I have ever seen 225.31(A) applied to inverter output circuits supplying a building. I would be curious what some of the solar people on here are seeing in regards to this.

2) I have not seen that applied in the "other direction" either.

3) Makes sense.

4) Ok so reading it few more times, I think I get it. The exception should just be for (1) it seems.

 

[jaggedben]

Where the code says 'supply' in Chapter 2 without obvious other context or meaning I interpret that as energization and ignore energy flow direction. So a grid-tied inverter output from a ground mount would not need a disconnect at the house, but it would need one at the ground mount. If not to meet 225, it would still need one for 690.15 isolation if the breaker at the house is not within sight. If there were an MID at the house and a multi mode inverter involved, then the circuit might need disconnects at both ends because either structure could energize the other.

If you have a service or feeder disconnect on the outside of the building that deenergizes the inverter output (in the required time) then the requirements of 690.12 are met, and no extra disco is needed, maybe just a label. If there's a microgrid that could keep the inverter output energized then you're likely going to need some other 690.12 initiation device. I suppose the grey area is on a one-or-two family dwelling with an older (grandfathered) service or feeder disconnect that's inside; in that case maybe an additional outside disconnect could be required, although that'd be pretty a stupid requirement. On newer installs they're requiring an outside disconnect for the utility supply (emergency disco etc.), so you'd have that anyway.

 

[pv_n00b]

But then it appears that the conductors need to terminate ON the building, so isn't that essentially saying yes rapid shut down applies?

Once the inverter output circuit enters the building that section of conductor falls under RSD if it is more than 3' long. The array and circuit between the array and where it penetrates the house do not fall under RSD.
In 690.12(B)(1) it gives you up to 3' of conductor after it penetrates the building before it falls under RSD. In any case the conductor will comply since when the outdoor main service disconnect is opened the inverter will shut down and the conductor will be under 30V within 30 seconds. The only way to make this non-compliant is if it is part of a microgrid or has an indoor main service disconnect. Then you would need a separate initiation device to shut it down.
The question about needing a separate disconnect at the house is not an RSD question. While I do not see a solid requirment in the NEC for the disconnect some people want to read 225 as if it applies to ground mount PV systems, which I don't. But your AHJ might, so put in a disconnect on the exterior just to keep the AHJ from flagging it if you know they are going to.