Inverter AC Output Circuit Conductor and OCPD (NEC 690.8(B))
Sizes the conductors and overcurrent device from a PV/ESS inverter to the point of connection: continuous output current = AC power / (voltage x [1 single-phase, sqrt(3) three-phase]), then NEC 690.8(B) / 705.60 / 240.4 size the conductor and OCPD at 125% of that current, rounding the OCPD up to the next standard size (240.6). A 9.6 kW inverter at 240 V single-phase puts out 40 A, so the conductor is at least 50 A (a #6 Cu at 75 C) on a 50 A breaker; the same inverter at 208 V three-phase is only 26.6 A. Use the inverter's RATED continuous AC output current from its datasheet if given, and check the 705.12 busbar / point-of-connection limit separately. Distinct from the DC-side pv-circuit-ampacity (690.8(A) 156% rule). A sizing estimate; the inverter datasheet, the AHJ, and the adopted NEC edition govern.
Formula and source
continuous_current_a = ac_power_w / (ac_voltage_v x [1 single-phase, sqrt(3) three-phase]); min_conductor_ampacity_a = 1.25 x continuous_current_a; ocpd_a = next standard size (NEC 240.6) >= 1.25 x continuous_current_a.
NEC 690.8(B) (continuous current), 705.60 (interconnected-source overcurrent), 240.4 (conductor protection), and 240.6 (standard OCPD sizes), by name; the inverter datasheet and the AHJ govern.
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