Breaker Sizing Calculator for Oregon
NEC 2023 breaker sizing math for EV charger installers working in Oregon.
Every EVSE branch in Oregon is treated as a continuous load per NEC 2023 Article 625 — the OCPD must be sized at 125% of the EVSE's listed maximum draw.
Worked example for Oregon
A 48 A continuous EV load requires a breaker rated 60 A (48 × 1.25 = 60.0 A, rounded up to the next standard size). The conductor downstream must carry that 60 A after Oregon's 0.88× ampacity correction.
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
Use a 100%-rated breaker only when the panel and breaker are both listed for 100% continuous duty — otherwise the 125% rule applies. Oregon inspectors enforce this rigorously on Article 625 work.