EV Charger Load Calculator for Idaho
NEC 2020 ev charger load math for EV charger installers working in Idaho.
Sizing an EV charger circuit in Idaho starts with NEC 2020 Article 625 — the EVSE branch must be sized to 125% of the continuous load. Hot-climate hot-band states like Idaho (96°F design ambient) also force a 0.82× ampacity correction at 75°C terminations.
Worked example for Idaho
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 Idaho's 0.82× 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
Idaho currently enforces the NEC 2020 edition, adopted in 2021. 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.
Idaho's primary EV-relevant utilities are Idaho Power, Avista Utilities, Rocky Mountain Power. Their make-ready, time-of-use, and demand-charge structures vary widely; pull the specific tariff before sizing service equipment.
Climate & Ampacity
Plan EV feeders against a 96°F ambient in Idaho — the resulting NEC 310.15(B) correction of 0.82× 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.
Idaho takeaway
Always cross-check the EVSE manufacturer's listed maximum overcurrent rating; Idaho Power may also have specific service-upgrade or load-management requirements you'll need to coordinate before final inspection.