Conduit Fill Calculator for Utah
NEC 2023 conduit fill math for EV charger installers working in Utah.
Multifamily and workplace EV installs in Utah routinely stack several #6 or #8 AWG home runs in shared EMT — at which point NEC 2023 Chapter 9 fill rules and 310.15(C)(1) adjustment factors both kick in.
Worked example for Utah
Stacking 3 × #6 AWG THWN-2 home runs (each with 2 conductors + EGC) in a single EMT means the raceway sees 6 current-carrying conductors. That triggers a 1.0× ampacity adjustment, on top of Utah's 0.82× temperature correction. Fill itself stays under the NEC 40% ceiling at roughly 1¼" EMT.
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
Always run the conduit-fill math first when laying out a multifamily EVSE rack — it's the constraint that most often forces a re-spec from #6 to #4 or from EMT to a larger trade size.