Power Calculator Calculator for Missouri
NEC 2020 power calculator math for EV charger installers working in Missouri.
Converting between kW and amps is the entry point for nearly every Missouri EV install spec — manufacturers publish kW, but the panel, breaker, and feeder live in amps.
Worked example for Missouri
A 11.5 kW EVSE draws roughly 48 A at 240 V single-phase, or 14 A at 480 V three-phase. Apply the NEC 2020 125% continuous-load multiplier before sizing the OCPD or feeder. Ameren Missouri typically meters DCFC sites at the 480 V three-phase service in Missouri.
Code & Utilities
Missouri 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.
Major electric utilities serving Missouri include Ameren Missouri, Evergy Missouri, Empire District Electric. Always verify the applicable tariff and any utility-specific requirements (CT cabinets, metering enclosures, demand limiters) at design time.
Climate & Ampacity
Plan EV feeders against a 95°F ambient in Missouri — 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.
Missouri takeaway
For three-phase math, always confirm the actual nameplate power factor — DCFC equipment is usually 0.95+ but older site-rated equipment can be lower, which changes the apparent power and the conductor pick.