No ground in PVC conduit?

[don_resqcapt19]

The NEC makes a distinction between bonding and grounding.

But not a very good one, because almost everything the NEC calls grounding is really bonding.

 

[ggunn]

I'm a bit confused. For each array, is the EGC run to all the different combiner boxes on the array, and then run with one of the output circuits to the remote PV tie? If that is the case, and assuming the EGC in one way or another bonds all equipment and racking, then I don't know what code section has been violated.

(Also what is the 'remote PV tie'? The inverter location? A junction box where all the raceways for the output circuits meet?)

It's a bipolar system, where there is an upper array and a lower array in series. The positive conductors from the upper array and the negative conductors from the lower array run all the way back to the inverter, but the negative conductors from the upper array and the positive conductors from the lower array do not; they run to a box (the remote PV tie) out near the arrays which connects the upper and lower arrays in series.

Every combiner box (there are five on the upper array and five on the lower array) has an EGC running back to the inverter ground ring, but only one combiner box each from the upper and lower arrays has an ECG running to the remote PV tie, and that is the issue.

The master electrician on site agrees with you that this is code compliant. I do not know of a code section which contradicts him, but it seems weird to me to run conduit without a ground wire. I am an engineer, not an electrician, and therefore not as code savvy as a lot of you guys; that's why I brought it here.

 

[jaggedben]

It's a bipolar system, where there is an upper array and a lower array in series. The positive conductors from the upper array and the negative conductors from the lower array run all the way back to the inverter, but the negative conductors from the upper array and the positive conductors from the lower array do not; they run to a box (the remote PV tie) out near the arrays which connects the upper and lower arrays in series.

Every combiner box (there are five on the upper array and five on the lower array) has an EGC running back to the inverter ground ring, but only one combiner box each from the upper and lower arrays has an ECG running to the remote PV tie, and that is the issue.

Aha, the plot thickens. :lol:

I assume there is also a grounded conductor connection from the remote PV tie to the inverter? If so, is there an EGC in that?

The master electrician on site agrees with you that this is code compliant. I do not know of a code section which contradicts him, but it seems weird to me to run conduit without a ground wire. I am an engineer, not an electrician, and therefore not as code savvy as a lot of you guys; that's why I brought it here.

Again, so far I don't see anything that to me violates code, as long as all the metal parts on both ends of those conduits are somehow bonded. And again, I'd be as much concerned with working out that the GFDI will operate properly, regardless of code. As the engineer, do you have an opinion on that?

 

[ggunn]

Aha, the plot thickens. :lol:

I assume there is also a grounded conductor connection from the remote PV tie to the inverter? If so, is there an EGC in that?

Yes, there is, but it's pretty small. It doesn't carry any current, it just grounds the conductors going to it when the inverter is off. I don't know if there is an EGC traveling with it.

Again, so far I don't see anything that to me violates code, as long as all the metal parts on both ends of those conduits are somehow bonded. And again, I'd be as much concerned with working out that the GFDI will operate properly, regardless of code. As the engineer, do you have an opinion on that?

I am not an inverter designer, but AE shows compliance with all the appropriate ANSI and IEEE standards.

 

[jaggedben]

I am not an inverter designer, but AE shows compliance with all the appropriate ANSI and IEEE standards.

I'm sure the inverter's GFDI meets the appropriate standard. But my point is that it relies on the EGC to carry fault current in order to operate properly. So the question you should be asking is; Will the EGC, as installed, carry any and all fault current back to the inverter's grounding bar?

 

[ggunn]

I'm sure the inverter's GFDI meets the appropriate standard. But my point is that it relies on the EGC to carry fault current in order to operate properly. So the question you should be asking is; Will the EGC, as installed, carry any and all fault current back to the inverter's grounding bar?

Yes, I think so. There is plenty of copper between the racking and the the inverter through the ECG conductors that run with the positive conductors from the upper array and the negative conductors from the lower array directly back to the inverter through the combiner boxes.