Transformer Sizing Calculator for Louisiana
NEC 2020 transformer sizing math for EV charger installers working in Louisiana.
DCFC and large workplace EV deployments in Louisiana 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 Louisiana
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. Louisiana's 95°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
EV installations in Louisiana are governed by the 2020 National Electrical Code, in force since 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 Louisiana, you'll most often interconnect with Entergy Louisiana, Cleco Power, SWEPCO Louisiana. Each has its own service-upgrade timeline, EV rebate availability, and metering rules — confirm them before quoting commercial work.
Climate & Ampacity
In Louisiana, the 95°F summer ambient drives a 0.88× 75°C ampacity correction. Bake this into every Level 2 and DCFC conductor pick before you commit to a wire size. 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.
Louisiana takeaway
Coordinate primary-side voltage, impedance, and fault-current specs with Entergy Louisiana early — interconnection lead times for new pad-mounts in Louisiana can run 6-12 months on commercial DCFC sites.