Power Calculator Calculator for Washington
NEC 2020 power calculator math for EV charger installers working in Washington.
Converting between kW and amps is the entry point for nearly every Washington EV install spec — manufacturers publish kW, but the panel, breaker, and feeder live in amps.
Worked example for Washington
A 19.2 kW EVSE draws roughly 80 A at 240 V single-phase, or 23 A at 480 V three-phase. Apply the NEC 2020 125% continuous-load multiplier before sizing the OCPD or feeder. Puget Sound Energy typically meters DCFC sites at the 480 V three-phase service in Washington.
Code & Utilities
The applicable code in Washington is the NEC 2020, which the state adopted in 2023. 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.
Washington's primary EV-relevant utilities are Puget Sound Energy, Seattle City Light, Avista Utilities, Snohomish PUD. 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 87°F ambient in Washington — 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.
Washington 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.