Transformer Sizing Calculator for Kansas
NEC 2020 transformer sizing math for EV charger installers working in Kansas.
DCFC and large workplace EV deployments in Kansas 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 Kansas
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. Kansas's 99°F summer ambient does not directly derate the transformer, but it does push the secondary feeder ampacity down by 0.82× — so the secondary copper has to be sized accordingly.
Code & Utilities
The applicable code in Kansas is the NEC 2020, which the state 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.
In Kansas, you'll most often interconnect with Evergy, Kansas Electric Power Cooperative, Westar Energy. Always verify the applicable tariff and any utility-specific requirements (CT cabinets, metering enclosures, demand limiters) at design time.
Climate & Ampacity
Kansas'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.
Kansas takeaway
Coordinate primary-side voltage, impedance, and fault-current specs with Evergy early — interconnection lead times for new pad-mounts in Kansas can run 6-12 months on commercial DCFC sites.