Breaker Sizing Calculator for Utah
NEC 2023 breaker sizing math for EV charger installers working in Utah.
Every EVSE branch in Utah 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 Utah
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 Utah's 0.82× ampacity correction.
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
Use a 100%-rated breaker only when the panel and breaker are both listed for 100% continuous duty — otherwise the 125% rule applies. Utah inspectors enforce this rigorously on Article 625 work.