Back feeding 100A of solar

[Skunkel]

Greetings, we have plenty of projects where we are installing 25kw/ nearly 100A of solar. We had an electrician, who was also an inspector, that is suggesting there is code allowing your to back feed tapped onto a sub panel feeder wires -if the wire is rated for 100A and protected by breakers on both sides. This is all run back to a 200 MSP.

Does anyone know how/ which code allows this?

Another nugget this guy came up with and installed was an inverter sum panel. Again a larger system with 2 Enphase combiners -nearly 100As, breaker fed into a sub panel w main 100A main breaker feeding directly into 200A panel with 100A feed in breaker on opposite end of main conductor/ breaker feed.

Looking for clarification, has anyone else done this?
Can you explain where in code this is explained?

 

[wwhitney]

Every busbar and feeder between the inverters and the service needs to satisfy the rules in 705.12(B). A feeder interconnection upstream of a sub panel avoids the need to worry about the sub panel, and the feeder interconnection rules are pretty reasonable. But none of the ideas you mentioned would change the need to comply with 705.12(B) at upstream panels, i.e the service panel.

Cheers, Wayne

 

[jaggedben]

Yes both things are possible in some situations, contingent on various details that haven't been described or clarified. There are rules in 705.12 for tapping feeders. There's really no substitute for carefully reading and understanding all the rules in 705.12. There have been numerous threads here on those rules, do a search.

 

[ggunn]

Every busbar and feeder between the inverters and the service needs to satisfy the rules in 705.12(B). A feeder interconnection upstream of a sub panel avoids the need to worry about the sub panel, and the feeder interconnection rules are pretty reasonable. But none of the ideas you mentioned would change the need to comply with 705.12(B) at upstream panels, i.e the service panel.

Cheers, Wayne

True, but if the main panel is MLO, 705.12(B)(3) does not apply.

 

[BackCountry]

Greetings, we have plenty of projects where we are installing 25kw/ nearly 100A of solar. We had an electrician, who was also an inspector, that is suggesting there is code allowing your to back feed tapped onto a sub panel feeder wires -if the wire is rated for 100A and protected by breakers on both sides. This is all run back to a 200 MSP.

Does anyone know how/ which code allows this?

Another nugget this guy came up with and installed was an inverter sum panel. Again a larger system with 2 Enphase combiners -nearly 100As, breaker fed into a sub panel w main 100A main breaker feeding directly into 200A panel with 100A feed in breaker on opposite end of main conductor/ breaker feed.

Looking for clarification, has anyone else done this?
Can you explain where in code this is explained?

That would work if your main panel’s summed breakers don’t exceed the bus bar. It wouldn’t really matter if there’s a sub panel in that scenario or not, see 705.12(B)(3)