Solar AC Disconnect vs Rapid Shutdown Entering a Building

[darunedefig]

Trenched AC wires run from a detached shed/garage/ground mount with solar to a house.
Normally before I penetrate a house I would place an AC disconnect on the exterior wall of the house.
Following NEC 2017,
"225.32 Location. The disconnecting means shall be installed
either inside or outside of the building or structure served or
where the conductors pass through the building or structure.
The disconnecting means shall be at a readily accessible location
nearest the point of entrance of the conductors. For the
purposes of this section, the requirements in 230.6 shall be
utilized."

I have this one job where the customer is wanting us to penetrate the basement from the trench, run conduit across basement,
then penetrate back out to exterior wall, and then place a rapid shutdown disconnect next to the utility meter.
Normally I would be installing two disconnects, with one near utility meter and another disconnect prior to the wires from the solar array entering the building.
Looking at this forum most of the posts that I saw concerning this are prior to rapid shutdown and prior to 2017.

In NEC 2017,2020,or 2023, is there anything in the code that only requires the rapid shutdown device where 225.32 does not apply?
Can I get away with the one disconnect by the utility meter?

 

[jaggedben]

Trenched AC wires run from a detached shed/garage/ground mount with solar to a house.

Okay, I'm understanding you to be describing a grid-tie-only solar system on a building or structure remote from the house, with the utility service at the house, and no backup power or DC coming from the remote location to the house. My responses below assume all this.

Normally before I penetrate a house I would place an AC disconnect on the exterior wall of the house.
Following NEC 2017,
"225.32 Location. The disconnecting means shall be installed
either inside or outside of the building or structure served or
where the conductors pass through the building or structure.
The disconnecting means shall be at a readily accessible location
nearest the point of entrance of the conductors. For the
purposes of this section, the requirements in 230.6 shall be
utilized."

Why? The feeder from the building or structure with solar does not energize the house.

I have this one job where the customer is wanting us to penetrate the basement from the trench, run conduit across basement,
then penetrate back out to exterior wall, and then place a rapid shutdown disconnect next to the utility meter.

You don't need a separate rapid shutdown disconnect at all on the house if the array is only at the remote building. Moreover, your service disconnect can usually serve as the rapid shutdown switch. So you don't need a separate rapid shutdown switch, or any separate solar disconnect at the house according to the NEC. The utility might require one.

Normally I would be installing two disconnects, with one near utility meter and another disconnect prior to the wires from the solar array entering the building.

I don't see why you need either disconnect per the NEC. Again, the utility might require one.

In NEC 2017,2020,or 2023, is there anything in the code that only requires the rapid shutdown device where 225.32 does not apply?
Can I get away with the one disconnect by the utility meter?

Honestly I think you need to read through all of 690.12 (Rapid Shutdown) and better understand the requirements. A rapid shutdown switch is only required at the building with the array(s), and it can be the service or feeder disconnect if that initiates rapid shutdown with your inverter technology.

I also think you are over interpreting 225.32. Unless the solar provides some kind of backup power that energizes the feeder that connects to the house, it doesn't 'supply' the house IMO. So you don't need a 225.32 disconnect at the house in that situation. You would need one at the building with the solar.

 

[darunedefig]

Your assumptions are correct. Grid-tie only.

AHJ wants us to place solar disconnect next to utility meter.

To make the question I am trying to ask easier, let us forget about the remote building.
If it went from remote ground mounted solar array with micro inverters -> to Trench -> to conduit up exterior wall of home -> (!!!) ->then conduit to penetrate into basement -> to conduit along basement wall -> conduit penetrating to exterior on opposite side of house -> then up to the main solar disconnect, next to the utility meter
...then it seems @jaggedben , you are saying in your opinion that an additional disconnect is not needed on home prior to the conduit penetrating the basement from the solar system, (!!!).

I have had an inspector require the disconnect quoting "225.32" before.

I think I understand your interpretation that solar doesn't 'supply' the house. I just need to figure out how best to articulate that to an inspector.
I guess solar is only a supply when the main solar disconnect connects to the existing home main service panel, which when doing a supply side connection we have covered by the solar disconnect by utility meter.
Or were you saying solar is never a supply? Since it will shut down when the grid shuts down for on-grid systems.
Solar is creating power, "supplying power", so it does seem strange not calling it a supply.

 

[ggunn]

Many (Most? All?) AHJs require a PV disconnect on the outside of a building if there is solar on the roof, irrespective of where the point of interconnection is.

 

[jaggedben]

I have had an inspector require the disconnect quoting "225.32" before.

I think I understand your interpretation that solar doesn't 'supply' the house. I just need to figure out how best to articulate that to an inspector.
I guess solar is only a supply when the main solar disconnect connects to the existing home main service panel, which when doing a supply side connection we have covered by the solar disconnect by utility meter.
Or were you saying solar is never a supply? Since it will shut down when the grid shuts down for on-grid systems.
Solar is creating power, "supplying power", so it does seem strange not calling it a supply.

So yes, that is the crux of the issue regarding such an extra disconnect, whether solar is a supply. If you want to be legalistic about it, you can claim the solar supplies the house for the purposes of 225.32, since at certain times power and energy will flow from the array to the house. But this is really a pretty unreasonable interpretation, because such a disconnect just doesn't provide the safety function that 225.32 is there to provide, namely to be able to cut off power to the house. It's misleading and wasteful to put a disconnect that someone would think turns off power to the feeder in the house, but does not. Also clearly 225.32 was written before grid-interactive inverters. I would hope we don't need another sentence or clarification in the code on this, but maybe we do.

I suspect that the inspector did not understand how grid tie systems work. I've run into inspectors who didn't understand that an additional disconnect of this type does essentially nothing. If you want to de-energize all the conductors in the house and leaving the house, you turn off the service disconnect. An additional disconnect just wastes the time of a first responder and potentially confuses them about which conductors are energized.

Note that where you really might need a 225.32 disconnect is at the ground mount array, since that is energized from the grid and you might want to shut off power from the utility supply to work on the array.

So, yeah, you understand my interpretation. But if you have an unreasonable AHJ who wants to be legalistic about the exact letter of the code, you may still have to install an extra, useless disconnect.

The only thing to add is not to confuse the requirement in 225.32 with rapid shutdown requirements. They are different things.

 

[jaggedben]

Many (Most? All?) AHJs require a PV disconnect on the outside of a building if there is solar on the roof, irrespective of where the point of interconnection is.

Leaving aside rapid shutdown, that's not true around here. The building departments don't require one, and PG&E only requires it for 3-phase, CT meters, or greater than 320A meters.