Chase branch circuit subpanel through solar disconnect

[brycenesbitt]

What relevant concerns would you see with this odd, but, seemingly safe sketch design?



Currents are not a problem, as anything used by the new subpanel will either reduce the current through the main panel breaker, or just
reverse the current flow.

CEC Section 705.12 and NEC Section 690-64(b)(1) wants a "dedicated" circuit for the solar. Is the demarcation point the disconnect or the main panel?
In other words could the dedicated circuit be defined to start at the right half of the diagram, downstream of the mechanical disconnect?



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The solar inverter has two disconnects both within sight of the unit: a 30A breaker at the main panel, and the above flip switch disconnect.
The wires are #8, with the neutral passing straight through the disconnect box. Total conduit length is about 10 feet from main to inverter.

The main panel has only two conduits that transit through a stucco wall. The goal is to share one of those two conduits
to avoid the hassle of a third penetration. While breakers could be added to the old subpanel, it's a terrible icky Federal Pacific model.

See also

Chase branch circuits through main disconnect.

Yes, it doesn't need a drip loop, The problem is that I don't have enough slack in the service cable to cut it, put a new meter in and splice it. They make new conductor;) You probably only needing 10-20 foot lengths not a 1000' reel.

forums.mikeholt.com

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Is there a conduit fill table for mixed wire sizes, e.g. four #8s plus 4 #12's?
Is four #8's plus four #12's acceptable in the left half conduit?

 

[Fred B]

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Is there a conduit fill table for mixed wire sizes, e.g. four #8s plus 4 #12's?
Is four #8's plus four #12's acceptable in the left half conduit?

See chapter 9 tables note (6) "..., use actual dimensions or Table 5 and Table 5A for dimensions of conductors and Table 4 for the applicable conduit or tubing dimensions." Then do the math.

 

[Fred B]

What relevant concerns would you see with this odd, but, seemingly safe sketch design?

View attachment 2553294

Currents are not a problem, as anything used by the new subpanel will either reduce the current through the main panel breaker, or just
reverse the current flow.

CEC Section 705.12 and NEC Section 690-64(b)(1) wants a "dedicated" circuit for the solar. Is the demarcation point the disconnect or the main panel?
In other words could the dedicated circuit be defined to start at the right half of the diagram, downstream of the mechanical disconnect?

View attachment 2553295

---------------------------------------------
The solar inverter has two disconnects both within sight of the unit: a 30A breaker at the main panel, and the above flip switch disconnect.
The wires are #8, with the neutral passing straight through the disconnect box. Total conduit length is about 10 feet from main to inverter.

The main panel has only two conduits that transit through a stucco wall. The goal is to share one of those two conduits
to avoid the hassle of a third penetration. While breakers could be added to the old subpanel, it's a terrible icky Federal Pacific model.

See also

Chase branch circuits through main disconnect.

Yes, it doesn't need a drip loop, The problem is that I don't have enough slack in the service cable to cut it, put a new meter in and splice it. They make new conductor;) You probably only needing 10-20 foot lengths not a 1000' reel.

forums.mikeholt.com

---------------------------------------------
Is there a conduit fill table for mixed wire sizes, e.g. four #8s plus 4 #12's?
Is four #8's plus four #12's acceptable in the left half conduit?

You should also continue reading Article 690, go to 690.31(B) refers to "PV 'source' circuits and PV 'output' circuits shall not be permitted in the same raceway, ....., junction box, or similar fittings as conductors,......, branch circuits of other non-PV systems"

 

[Carultch]

You should also continue reading Article 690, go to 690.31(B) refers to "PV 'source' circuits and PV 'output' circuits shall not be permitted in the same raceway, ....., junction box, or similar fittings as conductors,......, branch circuits of other non-PV systems"

"PV source circuits" and "PV output circuits" refer to the DC side of the system. It is called an inverter output circuit once it is AC, which you are permitted to mix in the same wiring structure with other AC wiring.

It is code-compliant to share the conduit for both the inverter output circuit and the circuit that serves the load center, assuming you've accounted for the conduit fill and bundling ampacity adjustments. What is not code-compliant, related to the OP's concept, would be to tap the load center off of the inverter's output circuit in the presumably unfused disconnect, which would make the inverter's output circuit no longer be a dedicated circuit. Dedicated means that the inverter connects directly an OCPD, without any other loads branching off of this circuit in between it and the first OCPD that serves it.