Inverter and array grounding

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I have a roof mount 250kw with 10 Inverters
I am running 10 home runs with 2 strings each with a #6 green for bonding array.
When I bring all 10 conduits into a gutter ,can I run all #6 into a ground buss and then up to DC side of inverter.
What is the best practice.
?

Question on AC side
In the same gutters should I use a irreversible crimp with ac ground to dc ground or go to gr buss.

Thank You in advance
 

GoldDigger

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Depends on whether the conductors in question are EGCs or GECs or both combined, or maybe even just bonding jumpers. Only GECs need irreversible splice except where they terminate to an allowed point.
 
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jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
Ground bar is fine then on the DC side.

Technically the California code still requires a GEC on the AC side, which means irreversible crimps. But for TL inverters all the AHJs I've worked with have stopped enforcing that, at least with regard to size, because UL says it's not required. Your AHJ may still ask you for irreversible crimps on the AC side though.

Since you mentioned the same gutters keep in mind that AC and DC must be separated by a partition if they are in the same raceway. It's not always enforced by I have always arranged my wiring so that AC and DC are not wrapped around each other and a partition could be inserted.
 
Gutters and grounding

Gutters and grounding

Ground bar is fine then on the DC side.

Technically the California code still requires a GEC on the AC side, which means irreversible crimps. But for TL inverters all the AHJs I've worked with have stopped enforcing that, at least with regard to size, because UL says it's not required. Your AHJ may still ask you for irreversible crimps on the AC side though.

Since you mentioned the same gutters keep in mind that AC and DC must be separated by a partition if they are in the same raceway. It's not always enforced by I have always arranged my wiring so that AC and DC are not wrapped around each other and a partition could be inserted.
We always keep wires separated ,however we never have installed partitions. Do they make especially partitions for gutters.?

Also we take the ac egc from main ac source to AC disco to Subpanel ground buss
Then from Subpanel to ac side of inverters
We also install a gr buss in gutters and run #6 bare from Subpanel to gr buss.
Then we run #6 from DC side of inverter to array junction box and irreverase crim to array bond on racking
When I come back to gutter should we irreverase crimp to ac ground or can we take to gr buss.
Otherwise the only bond will be with ground bushings to gr buss in gutter.
Trying not to overground?
Thank You
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
We always keep wires separated ,however we never have installed partitions. Do they make especially partitions for gutters.?

Also we take the ac egc from main ac source to AC disco to Subpanel ground buss
Then from Subpanel to ac side of inverters
We also install a gr buss in gutters and run #6 bare from Subpanel to gr buss.
Then we run #6 from DC side of inverter to array junction box and irreverase crim to array bond on racking
When I come back to gutter should we irreverase crimp to ac ground or can we take to gr buss.
Otherwise the only bond will be with ground bushings to gr buss in gutter.
Trying not to overground?
Thank You

Irreversible crimps are not really necessary, practically speaking. A listed grounding accessory like a ground bar is plenty good enough IMO. It's just that CA code has not caught up to the current industry thinking so if your AHJ chooses to ask for irreversible crimps you'll have to abide by that, you don't have much argument.

The context is that the irreversible crimp is a grounding electrode conductor requirement, and when you have a grounded PV conductor the idea is that no one should be able to easily unground that conductor, even temporarily. (This same concept applies to AC grounded conductors.) However with TL inverters there is no grounded PV conductor. And in fact in the 2017 version of the code it will be recognized that even conductors grounded through a fuse are not solidly grounded and a connection to the actual earth is not critically important for safety. So as long as you follow proper EGC methods for all bonding you are okay. Note 250.92 applies to bonding for DC if over 250V.
 
Grounding

Grounding

Irreversible crimps are not really necessary, practically speaking. A listed grounding accessory like a ground bar is plenty good enough IMO. It's just that CA code has not caught up to the current industry thinking so if your AHJ chooses to ask for irreversible crimps you'll have to abide by that, you don't have much argument.

The context is that the irreversible crimp is a grounding electrode conductor requirement, and when you have a grounded PV conductor the idea is that no one should be able to easily unground that conductor, even temporarily. (This same concept applies to AC grounded conductors.) However with TL inverters there is no grounded PV conductor. And in fact in the 2017 version of the code it will be recognized that even conductors grounded through a fuse are not solidly grounded and a connection to the actual earth is not critically important for safety. So as long as you follow proper EGC methods for all bonding you are okay. Note 250.92 applies to bonding for DC if over 250V.

Thank You for all your help.
 
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