Neutral, is it required?

[Jacob.Ball]

I have had many questions recently regarding the AC side of PV Installations. My question is, if you run L1, L2, and a ground from your sub panel to an inverter, do you need a neutral? If so where does it state this in the code?



Most Inverters come with the ability to wire them without a neutral.

I also know that most AHJ's will fail an installation if the neutral is not present.

 

[LarryFine]

Welcome to the forum!


Of the ones I've seen, the inverter neutral is used, because the loads are 120v as well as 240v. Generally, if the loads don't require it, the neutral must still be run to, and bonded to the system EGC in the main disconnect enclosure.

So, if your loads are 240v only, and the main disconnect is in the inverter itself, I'd say you don't need it. But, if the main is in the sub-panel (in this case), it should be terminated there. Is the inverter output's neutral bonded within the inverter?

 

[Jacob.Ball]

The Inverters come with the capability to since the neutral, or through changing the Utility configuration jumpers ignore the neutral.

My main question is what article in the NEC requires a neutral, and is there any article that states that you do not need a neutral.

 

[e57]

Start at about 250.30 an onwards... :roll: IMO you are providing supplimentary power to circuits without a full circuit path for the neutral. Unless you are only supplying 240 loads. What about all of those 120 circuits? IF the PV system stays on for some reason while the primary source is off - what gets fed to the 120 loads?

 

[Jacob.Ball]

It the case that there is a change in AC voltage, or frequency (outside of the ANSI range) the inverter will immediately stop production. Then it will stay offline for 5 minutes, then attempt to reconnect to the grid. I found Article 310.15 (B)(4).
The way I read it, if you have a split phase system, it is not required to have a neutral. I think I am misinterpreting it though.

 

[e57]

You are only providing 240 to an unbalanced 240/120 system. The apple is current carrying - so should the orange IMO.

Look at 250.20 A~D See which applies to you? The return path for all 120 circuits is missing.... Yet being supplied in part by the PV system.