Wire Size Calculator for Utah
NEC 2023 wire size math for EV charger installers working in Utah.
Wire sizing in Utah is governed by NEC 2023 Table 310.16, with the state's 99°F summer ambient driving a 0.82× correction factor at 75°C terminations per Table 310.15(B)(1).
Worked example for Utah
A 100 A continuous EV branch needs a conductor whose corrected ampacity meets or exceeds 100 A. In Utah's 0.82× correction, that means picking a conductor whose 30°C-rated ampacity is at least 122 A. For copper THWN-2 in EMT, that typically lands at #2 AWG; aluminum requires one to two sizes larger.
Code & Utilities
Utah currently enforces the NEC 2023 edition, 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.
Utah's primary EV-relevant utilities are Rocky Mountain Power, Murray City Power, Logan Light & Power. Their make-ready, time-of-use, and demand-charge structures vary widely; pull the specific tariff before sizing service equipment.
Climate & Ampacity
Utah's representative summer design ambient is around 99°F, which yields a 0.82× 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.
Utah takeaway
Don't forget conduit-fill derating per NEC 310.15(C)(1) when more than three current-carrying conductors share a raceway — a common condition on multifamily and workplace EVSE home-run racks in Utah.