I am working on a medium sized commercial solar PV project. The "point of connection" (NEC 705) will be located on the line side of a 5,000A circuit breaker, 480Y/277VAC, 3ph, 4W that is part of a 5,000A switchboard. The existing 5,000A circuit breaker includes Ground Fault Protection for Equipment in accordance with NEC 230.95. The solar PV source circuit will be a 1,000A feeder. This existing 5,000A circuit breaker is not the service disconnect. The service disconnect is upstream on the other side of a step-down transformer so it does not have Ground Fault Protection. The question I have is whether the 1,000A solar OCPD needs to have Ground Fault Protection. The UL listed solar PV inverters include ground fault protection, but only for the DC side, not the AC side. To meet the local utility company requirement, I need to have a visible blase disconnect at the point of connection, so that would normally mean I am using a fused disconnect, not an LSIG circuit breaker. I have read and re-read the various references to Ground Fault Protection for Equipment in the NEC to the point where I think I have confused myself. The existing building distribution remains protected by the existing Ground Fault Protection. The "unprotected" conductors or equipment will be the solar PV inverter output circuit to the point of connection, which for most of the 300 ft run is external to the building. Does that segment need Ground Fault Protection?
All thoughts and questions are most welcome.
So let's see...
1) The relevant section is actually 215.10, which requires GFP. (The service is presumably greater than 1000V, and thus not required to meet 230.95, but the requirements are the same for these types of feeders.)
2) You could theoretically replace your fused disconnect with a non-fused disconnect plus a breaker with GFP, or add an independent GFP device,
however...
3) You are prohibited in 705.32 from connecting your solar on the load side of ground-fault protection, unless you provide 'ground fault protection for equipment from all ground-fault current sources', however you are supposed to do that. So simply connecting through a GFP breaker is not sufficient.
4) Good luck finding a breaker with GFP that is suitable for backfeed.
5) A GFP device that is approved to be installed at the inverter might get around the problem, if you can find such a thing. That issue could be considerably complicated by how many inverters you are using, although I guess a single 1000A device would protect the feeder that requires protecting.
The bottom line question becomes... What's your AHJ gonna require? Will they agree with any interpretation we agree on here?
You
may be able to convince the AHJ that, not being able to find a GFP device that is suitable for sensing GFP in both directions, they should allow you under the third paragraph of 90.4 to install the feeder without GFP. That's really above my pay grade to determine if that's true.
Other thoughts...
I believe DC side ground-fault detection is irrelevant to the question.
The solar PV source circuit will be a 1,000A feeder.
In context it seems pretty clear this refers to your AC inverter output circuit. Please do not refer to this as a PV source circuit. That term refers to DC circuits connected directly to solar modules.
Final thought:
Any possibility of dividing the solar system up into two feeders that aren't required to have GFP?
