EV Charger Load Calculator for California
NEC 2023 ev charger load math for EV charger installers working in California.
Sizing an EV charger circuit in California starts with NEC 2023 Article 625 — the EVSE branch must be sized to 125% of the continuous load. Hot-climate hot-band states like California (95°F design ambient) also force a 0.88× ampacity correction at 75°C terminations.
Worked example for California
For a 48 A Level 2 charger on a 240 V single-phase circuit, the OCPD is sized to 60 A (48 × 1.25 = 60.0 A, rounded up to the next standard breaker). The conductor must carry 60 A after California's 0.88× correction — that typically lands at #6 AWG copper THWN-2 for a residential garage run, with conduit fill checked separately if you're stacking multiple home runs.
Code & Utilities
California currently enforces the NEC 2023 edition, adopted in 2023. 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.
Major electric utilities serving California include Pacific Gas & Electric (PG&E), Southern California Edison, San Diego Gas & Electric, LADWP, SMUD. Each has its own service-upgrade timeline, EV rebate availability, and metering rules — confirm them before quoting commercial work.
Climate & Ampacity
Plan EV feeders against a 95°F ambient in California — the resulting NEC 310.15(B) correction of 0.88× is what trims a #6 THWN-2 down to its true continuous rating. 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.
California takeaway
Always cross-check the EVSE manufacturer's listed maximum overcurrent rating; Pacific Gas & Electric (PG&E) may also have specific service-upgrade or load-management requirements you'll need to coordinate before final inspection.