Hey folks,
One of our systems was inspected this week and failed for a couple reasons, but this one particularly stumped me, so I've been reading and re-reading the code today. It logically makes sense, but less so intuitively, and I'm wondering if the inspector's interpretation jives with your understanding and if there's anything else I'm missing.
For reference, this was an AHJ in Colorado, and the applicable code cycle in 2023 NEC. Here's a quick sketch of the general set-up as installed:
I only included the relevant details since nothing else was problematic for the inspection. Meter and service disconnect were on a pedestal meter removed from the home. Feeders enter the home through an LB on the exterior wall and immediately terminate in the subpanel in a main breaker (200A) with ampacity matching the service disconnect. We interconnected the PV with Ilsco piercing connectors inside the subpanel by tapping into the load side feeders before the subpanels main breaker. These taps run less than 10 feet immediately out the back of the panel and then connect to an appropriately sized AC disconnect, which is fused.
We've installed this exact set-up many times before and never had any issue. This time, however, we were dinged by the inspector, who said: "Tap disconnect required to be grouped with main disc in garage-225.34". The relevant section here would be 225.34(A), which states: "The two to six disconnects as permitted in 225.33 shall be grouped. Each disconnect shall be marked to indicate the load served."
I was stumped with this because I've only ever seen this code cited when dealing with service disconnections, or disconnects immediately connected to the line side of the service. While reading through and discussing this with a friend, I believe 225.30 is also relevant here. "A building or other structure that is served by a branch circuit or feeder on the load side of a service disconnecting means shall be supplied by only one feeder or branch circuit unless permitted in 225.30(A) through (F). For the purpose of this section, a multiwire branch circuit shall be considered a single circuit." This seems to mean that the conductors feeding the subpanel, despite being on the load side of the service disconnecting means, are considered "supply" feeders from the point where they enter the home and that implies that the home cannot have more than 6 disconnects connected to this feeder, and these disconnects must be grouped. The main breaker in the subpanel is considered one of these disconnects. I think I can agree with this interpretation.
Where I get tripped up is:
Parallel generation is not considered a load. 225.34(A) specifically states that the 2-6 disconnects that are required to be grouped are also required to marked with which load is being served by the disconnect. Does this discrepancy matter? My understanding of the NEC (which is admittedly limited, only been in the industry for a couple years with no field experience) tells me that this could mean the grouping requirement only applies to LOADS. If the tap were leading to a load, or a load center used to feed multiple loads, it would make perfect sense to me that the disconnecting means for the tap needs to be grouped with the disconnecting means for the other subpanel given the above assumptions. However, the PV is tapped into the supply feeder as if it were part of the supply. Why does it need to be grouped with load side disconnects for the building? Does 225.34(A) really apply here? 225.30(A) permits parallel generation as a reason to have more than one feeder for the same supply. Shouldn't the PV + utility be considered the same supply for the building, and the 6 handle rule only apply if there isn't a single point of disconnect for the loads downstream? Intuitively, my brain is just thinking of the interconnected PV as wholly separate from loads connected to the service, and that as long as the loads comply with disconnecting means requirements and the AC disconnect for the PV complies with all requirements in 705, we should be good to go. The inspector and discussion with my friend lead me to believe it's not that simple.
I think I'm just running on fumes at this point and it'll all click Monday morning, but I'm just fussed about the fact that we've never had any inspectors push back on this set-up. If his interpretation is correct, then I'd have expected way more friction across the many installs we've done this way since we've definitely been doing it wrong. Hoping to get some additional insight and firm opinions from the more experienced on this forum - I'm here to learn. Thanks in advance, all.
-B
One of our systems was inspected this week and failed for a couple reasons, but this one particularly stumped me, so I've been reading and re-reading the code today. It logically makes sense, but less so intuitively, and I'm wondering if the inspector's interpretation jives with your understanding and if there's anything else I'm missing.
For reference, this was an AHJ in Colorado, and the applicable code cycle in 2023 NEC. Here's a quick sketch of the general set-up as installed:
I only included the relevant details since nothing else was problematic for the inspection. Meter and service disconnect were on a pedestal meter removed from the home. Feeders enter the home through an LB on the exterior wall and immediately terminate in the subpanel in a main breaker (200A) with ampacity matching the service disconnect. We interconnected the PV with Ilsco piercing connectors inside the subpanel by tapping into the load side feeders before the subpanels main breaker. These taps run less than 10 feet immediately out the back of the panel and then connect to an appropriately sized AC disconnect, which is fused.
We've installed this exact set-up many times before and never had any issue. This time, however, we were dinged by the inspector, who said: "Tap disconnect required to be grouped with main disc in garage-225.34". The relevant section here would be 225.34(A), which states: "The two to six disconnects as permitted in 225.33 shall be grouped. Each disconnect shall be marked to indicate the load served."
I was stumped with this because I've only ever seen this code cited when dealing with service disconnections, or disconnects immediately connected to the line side of the service. While reading through and discussing this with a friend, I believe 225.30 is also relevant here. "A building or other structure that is served by a branch circuit or feeder on the load side of a service disconnecting means shall be supplied by only one feeder or branch circuit unless permitted in 225.30(A) through (F). For the purpose of this section, a multiwire branch circuit shall be considered a single circuit." This seems to mean that the conductors feeding the subpanel, despite being on the load side of the service disconnecting means, are considered "supply" feeders from the point where they enter the home and that implies that the home cannot have more than 6 disconnects connected to this feeder, and these disconnects must be grouped. The main breaker in the subpanel is considered one of these disconnects. I think I can agree with this interpretation.
Where I get tripped up is:
Parallel generation is not considered a load. 225.34(A) specifically states that the 2-6 disconnects that are required to be grouped are also required to marked with which load is being served by the disconnect. Does this discrepancy matter? My understanding of the NEC (which is admittedly limited, only been in the industry for a couple years with no field experience) tells me that this could mean the grouping requirement only applies to LOADS. If the tap were leading to a load, or a load center used to feed multiple loads, it would make perfect sense to me that the disconnecting means for the tap needs to be grouped with the disconnecting means for the other subpanel given the above assumptions. However, the PV is tapped into the supply feeder as if it were part of the supply. Why does it need to be grouped with load side disconnects for the building? Does 225.34(A) really apply here? 225.30(A) permits parallel generation as a reason to have more than one feeder for the same supply. Shouldn't the PV + utility be considered the same supply for the building, and the 6 handle rule only apply if there isn't a single point of disconnect for the loads downstream? Intuitively, my brain is just thinking of the interconnected PV as wholly separate from loads connected to the service, and that as long as the loads comply with disconnecting means requirements and the AC disconnect for the PV complies with all requirements in 705, we should be good to go. The inspector and discussion with my friend lead me to believe it's not that simple.
I think I'm just running on fumes at this point and it'll all click Monday morning, but I'm just fussed about the fact that we've never had any inspectors push back on this set-up. If his interpretation is correct, then I'd have expected way more friction across the many installs we've done this way since we've definitely been doing it wrong. Hoping to get some additional insight and firm opinions from the more experienced on this forum - I'm here to learn. Thanks in advance, all.
-B