690.64(B)(2) ,2011 NEC, requires the sum of all over OCPD to be used when sizing the conductors. If I have a system with a 200 amp OCPD on the main switch gear feeding a PV panel (not a combiner box) and four 50 amp breakers in the panel being fed by the inverters, I would need to size my conductors at 80% of 400 amps. Is there any code compliant way to not use such large conductors?
690.64(B)(2) conductor sizing
- Thread starter acrwc10
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No, not on the load side, if there are loads or the ability to add them between main OCPD and the pv breakers.
And in that case, the busbar for the PV and any other busbar may need to meet those requirements too....
You can do a supply side connection, aka line side tie.
If those 4 @ (N) PV breakers were all main discos....you would be fine at 200a conductors.
Is this main 200A switchgear only for the PV? No house, bldg, loads? It might change things.
And in that case, the busbar for the PV and any other busbar may need to meet those requirements too....
You can do a supply side connection, aka line side tie.
If those 4 @ (N) PV breakers were all main discos....you would be fine at 200a conductors.
Is this main 200A switchgear only for the PV? No house, bldg, loads? It might change things.
jaggedben
Senior Member
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- Northern California
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- Solar and Energy Storage Installer
Talk to your AHJ.
Some would insist on the conductors being 84% of 400A. (It's 1/1.2 btw, not 1/1.25.)
Some would be fine with 200A for both conductors and panel rating.
Some would be okay with 200A for the conductors, and 84% of 400A for the panel, but only if the panel contains an additional 200A main OCPD.
First, I have to assume when you say the "PV panel" is not a combiner box, it is a [load] distribution panelboard.
Depends a lot on whether the "PV panel" is MCB or MLO. If MCB, the feeder conductors can be sized to the 200A switchgear OCPD. If MLO, it has to be sized at not less than the 84% of the sum all source OCPD's, as mentioned by jaggedben. For either case, the "PV panel" must be rated at not less than the 84% value. [ref: 705.12(D)(2)]
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