Transformer Sizing Calculator for West Virginia
NEC 2020 transformer sizing math for EV charger installers working in West Virginia.
DCFC and large workplace EV deployments in West Virginia typically need a dedicated 480 V three-phase service, which means sizing a pad-mount or dry-type transformer against the connected charger load plus the NEC 2020 continuous-load multiplier.
Worked example for West Virginia
A 240 kW DC fast charger draws roughly 289 A at 480 V three-phase. Applying the 125% continuous-load factor (240 × 1.25 ≈ 300 kVA), then rounding up to the next standard transformer rating gives a 300 kVA minimum. West Virginia's 88°F summer ambient does not directly derate the transformer, but it does push the secondary feeder ampacity down by 0.88× — so the secondary copper has to be sized accordingly.
Code & Utilities
West Virginia currently enforces the NEC 2020 edition, adopted in 2022. 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.
West Virginia's primary EV-relevant utilities are Appalachian Power, Mon Power, Potomac Edison. Each has its own service-upgrade timeline, EV rebate availability, and metering rules — confirm them before quoting commercial work.
Climate & Ampacity
Plan EV feeders against a 88°F ambient in West Virginia — the resulting NEC 310.15(B) correction of 0.88× 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.
West Virginia takeaway
Coordinate primary-side voltage, impedance, and fault-current specs with Appalachian Power early — interconnection lead times for new pad-mounts in West Virginia can run 6-12 months on commercial DCFC sites.