Grounding Conductor Calculator for Oregon
NEC 2023 grounding conductor math for EV charger installers working in Oregon.
EGC sizing in Oregon follows NEC 2023 Table 250.122, indexed off the upstream OCPD rating, with parallel rules for parallel sets and increased-conductor adjustments under 250.122(B).
Worked example for Oregon
For a 40 A EVSE branch, Table 250.122 calls for a minimum #10 Cu equipment grounding conductor. If you upsize the phase conductors for voltage drop in Oregon's long runs, NEC 250.122(B) requires the EGC to be upsized proportionally.
Code & Utilities
The applicable code in Oregon is the NEC 2023, which the state adopted in 2024. That includes Article 625 (Electric Vehicle Power Transfer System) requirements: 125% continuous-load sizing on EVSE branch circuits, GFCI protection at outdoor receptacles, and provisions for energy management systems on shared circuits.
In Oregon, you'll most often interconnect with Portland General Electric, Pacific Power, Eugene Water & Electric Board. Each has its own service-upgrade timeline, EV rebate availability, and metering rules — confirm them before quoting commercial work.
Climate & Ampacity
Oregon's representative summer design ambient is around 88°F, which yields a 0.88× ampacity correction factor at 75°C terminations per NEC 310.15(B)(1). Because the correction is below 0.9, conductors that "look fine" on a 30°C ampacity table will not carry their nameplate current here — always derate explicitly.
Oregon takeaway
On DCFC sites with parallel feeder sets, each parallel raceway needs its own full-size EGC — a detail inspectors in Oregon catch frequently on commercial submittals.