Generator Output Conductor at 115% (NEC 445.13)
The conductor rule from a generator to its first overcurrent device, which estimators routinely get wrong: NEC 445.13(A) sets the ampacity at not less than 115% of the generator NAMEPLATE current -- not 125% of a computed load, not the connected running load. A 150 kW, 480 V three-phase generator at 0.8 pf draws 225.6 A nameplate, so the conductor must carry 1.15 x 225.6 = 259.4 A. Where the design prevents output above nameplate (overload-limited), the basis drops to 100% and it is just 225.6 A. Enter the nameplate current directly or derive it from kW, voltage, phase, and pf. The 110.14(C) termination limit and 310.15 adjustments still apply. A design aid; the AHJ governs.
Formula and source
nameplate = given, or kW x 1000 / (sqrt(3) x V x pf) three-phase, or kW x 1000 / (V x pf) single-phase; basis = overload_limited ? 1.00 : 1.15; required_ampacity = basis x nameplate.
The generator output-conductor ampacity rule of NEC 2023 445.13(A) -- not less than 115% of the generator nameplate current, or 100% where the design prevents output above the nameplate -- by name. A computational aid; the AHJ-adopted NEC edition governs.
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