EV Charger Load Calculator for Colorado
NEC 2023 ev charger load math for EV charger installers working in Colorado.
Sizing an EV charger circuit in Colorado starts with NEC 2023 Article 625 — the EVSE branch must be sized to 125% of the continuous load. Hot-climate warm-band states like Colorado (90°F design ambient) also force a 0.88× ampacity correction at 75°C terminations.
Worked example for Colorado
For a 40 A Level 2 charger on a 240 V single-phase circuit, the OCPD is sized to 50 A (40 × 1.25 = 50.0 A, rounded up to the next standard breaker). The conductor must carry 50 A after Colorado's 0.88× correction — that typically lands at #8 AWG copper THWN-2 for a residential garage run, with conduit fill checked separately if you're stacking multiple home runs.
Code & Utilities
The applicable code in Colorado is the NEC 2023, which the state 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.
Colorado's primary EV-relevant utilities are Xcel Energy Colorado, Colorado Springs Utilities, Tri-State Generation. Each has its own service-upgrade timeline, EV rebate availability, and metering rules — confirm them before quoting commercial work.
Climate & Ampacity
In Colorado, the 90°F summer ambient drives a 0.88× 75°C ampacity correction. Bake this into every Level 2 and DCFC conductor pick before you commit to a wire size. 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.
Colorado takeaway
Always cross-check the EVSE manufacturer's listed maximum overcurrent rating; Xcel Energy Colorado may also have specific service-upgrade or load-management requirements you'll need to coordinate before final inspection.