PV Wiring inside of building - Grounding?

[JAS]

Follow up to this thread: https://diysolarforum.com/threads/burnt-up-junction-box.54342/

Regarding the NEC Code for PV wiring inside of the building...

I spoke with my electrician about this. He wasn't familiar with that part of the NEC code requirement and wasn't sure why it was necessary to be in metal boxes/raceway/etc. That being said, he did say if using metal boxes/conduit, it would then require grounding.

Sooo... How (and where) do I ground all that too? I'm using an MPP AIO and it does not accept conduit connections to the case (nor do I want to attempt drilling new holes for the connection....not really any room to do so anyway).

I would have to terminate the conduit/MC prior to connection to the AIO. Was thinking possibly to another metal box with a DC breaker in it. Then I guess I could run a ground wire from that box?

 

[PreppenWolf]

I ran my PV wiring (underground) with a ground wire that was atrached to its own earth ground rod at the panels. And the left it terminated kend not connected to anything) at the PV breaker inside. I am using PVC. So if you dig up my conduit and don't know it's there, it grounds back to the panels, not through the house and then main panel. This lowers the probability of starting a fire in the house if the line is somehow cut/shorted in the underground run.

For yours I would do the same, but terminate the ground to the metal box instead.

 

[JAS]

For yours I would do the same, but terminate the ground to the metal box instead.

Do you mean the junction box where it penetrates the wall? Or the box I was referring to close to the AIO, housing an additional breaker?

 

[PreppenWolf]

I would ground it to every box along the way and to the last one at AIO. But do not ground it to the AIO's grounding location. You can use bare wire for grounds which makes ties at multiple locations easy.

 

[JAS]

So that opens a whole different can of worrms regarding where to ground the panel frames...

Many are now saying NOT to ground frames to a separate grounding rod and that the ground should be ran back to the system (What exact piece of equipment that is, IDK ? I guess either a standalone SCC or an AIO?) If the AIO, then that ground is derived from the AC input ground (in my case, the same ground as my AC service panel) And since my AIO doesn't have a grounding lug anyway, might as well run it back to the ground rod used by the AC service panel, right?

So now I also have to throw the metal junction boxes/conduit/raceway/mc cable, etc into the mix too... Ugh ?

 

[JAS]

I did find this link helpful: https://blog.gogreensolar.com/grounding-overview-for-do-it-yourself-solar

 

[PreppenWolf]

I grounded my panels to the same rod, at the panels. The frames of the panels are not part of the solar cell circuits. The panels are fully insulated in glass. The reason to ground the panel frames is incase of panels breaking and allowing a potential created on the frame, and for lightning protection.

Before your frames are grounded, there should be 0 volts. I.e. when you touch the panel frame you shouldn't get electrocuted. If you do the panel is faulty.

 

[PreppenWolf]

Wait, I missed a stop here. Where are your panels mounted? If they are on the house, you might be required to ground them to the same location. Mine are not on a building.

 

[PreppenWolf]

The link you posted is specific to roof mounted racking.

 

[JAS]

Wait, I missed a stop here. Where are your panels mounted? If they are on the house, you might be required to ground them to the same location. Mine are not on a building.

My panels are mounted on the side of my detached garage. Equipment is inside garage.

 

[JAS]

The link you posted is specific to roof mounted racking.

I don't see anything in that article that says it is specific to roof mounting?

 

[PreppenWolf]

Does that garage have electricity in it now that is supplied from the house?

If it is on a structure with current electrical service, I would 100% ground it to the main panel. I only ground mine separately because it doesn't make sense to bring a possible fire hazard into an occupied structure from a ground mount array. I.e. if you damaged the buried line to my house, I want the wires OUTSIDE the house to potentially melt/overheat, not the wires inside. Especially since I can isolate my PV both outside at the array and inside the house in the event that happened to completely remove the house from the damage.

 

[JAS]

Does that garage have electricity in it now that is supplied from the house?

Yes, it does. And the subpanel in the garage has it's own ground rod. I'm thinking to ground the panels (and any junction boxes/conduit inside the garage) to that same ground rod

 

[PreppenWolf]

Yes, it does. And the subpanel in the garage has it's own ground rod. I'm thinking to ground the panels (and any junction boxes/conduit inside the garage) to that same ground rod

That's what I would do.