PV Feeder To Detached Garage

[sketchy]

I have a job with Enphase microinverters on a detached garage. The IQ Combiner panel, which requires a neutral, is on the house. The solar panels are on the detached garage where they land into a combiner panel. The micros do not require a neutral to function so I never pull one in these situations. I've been given the OK to do so by the state of MN (2020 cycle) but this job is in WI (2017 cycle) and the inspector says I have to pull a neutral to the garage. She's citing 250.20(B)(1) and I tell her that the combiner does have a neutral but I don't need one at the garage as it will have no purpose, it just floats.
How is this any differetn than electric heat or EV chargers that don't use a neutral? I'm looking for more ammunition to fight back, any help would be greatly appreciated.

 

[retirede]

250.20(B)(1) is about grounding. It has nothing to do with the presence of a grounded conductor.

 

[pv_n00b]

What they are citing is a reason to run an EGC to the garage, not a neutral. There is some confusing there that you might be able to clear up by talking to them.

 

[jaggedben]

Inspector is just wrong.

Moreover, it might be better that the panel doesn't have a neutral, to discourage people from putting loads in it.

 

[sketchy]

I tried to make a case but she keeps going back to this:

250.20 Alternating Current Systems to Be Grounded
(B) Alternating Current Systems of 50 to 100 Volts: … that supply premises wiring and premises wiring systems shall be grounded under any of the following conditions:
(1) Where the system can be grounded so that the maximum voltage to ground on the ungrounded conductors does not exceed 150 volts.

Part of me wants to keep fighting but I also have to get the customer turned on and it's not that big of a deal to pull the wire. I just don't like doing something just because the inspector says so without a valid reason.

 

[wwhitney]

Just for the record, the "system" that 250.20(B)(1) is referring to (assuming no transformers on the premises wiring system) is all of the 120/240V AC wiring from the utility all the way to the AC input of the inverter. That system is grounded by having the neutral conductor earthed via the GEC at the service entrance. That system earthing covers the whole system, and even if the grounded conductor is absent somewhere in the system, the system is still grounded.

In other words, for the system to be grounded means that each conductor has a well-defined voltage to earth. That remains true even when the grounded conductor (at 0V to earth) is absent.

I'm sure you know all of the above, just try to remotely explain to your inspector. Interestingly Article 100 lacks a definition of "grounded system," so I think the best you could do is to 250.4(A)(1) and take the first sentence as an implicit definition of "grounded system".

Cheers, Wayne

 

[ggunn]

I just don't like doing something just because the inspector says so without a valid reason.

Welcome to my world.

 

[electrofelon]

I tried to make a case but she keeps going back to this:

250.20 Alternating Current Systems to Be Grounded
(B) Alternating Current Systems of 50 to 100 Volts: … that supply premises wiring and premises wiring systems shall be grounded under any of the following conditions:
(1) Where the system can be grounded so that the maximum voltage to ground on the ungrounded conductors does not exceed 150 volts.

Part of me wants to keep fighting but I also have to get the customer turned on and it's not that big of a deal to pull the wire. I just don't like doing something just because the inspector says so without a valid reason.

Wow, that inspector shouldn't be an electrical inspector. She doesn't seem to understand what SYSTEM grounding is. I think post #2 is the simplest and most succinct - that is about system grounding not a requirement to run a grounded conductor. Running a grounded conductor doesn't make the system grounded
Wow and sorry

 

[jaggedben]

I'm sorry too.

Maybe try showing her with your volt meter that there is a stable and consistent voltage to EGC from both L1 and L2? As Wayne said, 250.4(A)(1).
Article 100 definition also does say the ground connection can be 'extended' which is what your EGC does.

Best I can do. Good luck.

 

[pv_n00b]

I tried to make a case but she keeps going back to this:

250.20 Alternating Current Systems to Be Grounded
(B) Alternating Current Systems of 50 to 100 Volts: … that supply premises wiring and premises wiring systems shall be grounded under any of the following conditions:
(1) Where the system can be grounded so that the maximum voltage to ground on the ungrounded conductors does not exceed 150 volts.

Part of me wants to keep fighting but I also have to get the customer turned on and it's not that big of a deal to pull the wire. I just don't like doing something just because the inspector says so without a valid reason.

250.20(B) identifies which AC systems need to be grounded, not how they are to be grounded. So it does not require that a neutral be run with the phase conductors.
250.24(A) discusses how grounded systems are to be grounded. The grounded conductor or neutral only needs to be brought to the service disconnecting means, 250.24(C), where it is connected to the grounding electrode conductor and the equipment ground, 250.24(B). There is no requirement in the code the AHJ can cite that requires it to be brought past that point to have a grounded system.