FEEDER TAP 705.12(B)(2)(1b) NEC 2017

[Designer101]

Two questions,
if we follow feeder tap rule, doesn't it all the way have to follow 120 percent or any bus bars three rule when it finally lands to main panel bus bar. Any way final Inverter current will have to go through main panel , Some jurisdiction approves this connection and some doesn't asking again about 120 percent rule.

Two 7600 H SolarEdge inverter output is connected to existing feeder from sub panel. I understand the feeder has to be sized per 240.21(b), but how about using disconnect as a means of tap so you don't have to upsize( 705.12(b(2)(1b)??

SLD attached.
Thank you

 

[wwhitney]

1) Yes, 705.12(B) applies to every feeder or panel between the PV inverter and the utility. A feeder with an interconnection is subject to 705.12(B)(2)(1); if the feeder just has 2 ends, there's nothing to comply with. But the upstream panels with 2 sources of supply still need to comply with 705.12(B)(2)(3).

So in the diagram you posted, the service panel does not comply unless the busbar is rated 233A or more (that's (200A + 40A + 40A)/1.2), or at least the sum of all breakers in the panel, excluding the 200A main breaker.

2) Using the disconnect as shown complies with 705.12(B)(2)(1)(b).

Cheers, Wayne