Power Calculator Calculator for Massachusetts
NEC 2023 power calculator math for EV charger installers working in Massachusetts.
Converting between kW and amps is the entry point for nearly every Massachusetts EV install spec — manufacturers publish kW, but the panel, breaker, and feeder live in amps.
Worked example for Massachusetts
A 150 kW EVSE draws roughly 625 A at 240 V single-phase, or 180 A at 480 V three-phase. Apply the NEC 2023 125% continuous-load multiplier before sizing the OCPD or feeder. Eversource Energy typically meters DCFC sites at the 480 V three-phase service in Massachusetts.
Code & Utilities
The applicable code in Massachusetts is the NEC 2023, 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.
Major electric utilities serving Massachusetts include Eversource Energy, National Grid, Unitil Massachusetts. Each has its own service-upgrade timeline, EV rebate availability, and metering rules — confirm them before quoting commercial work.
Climate & Ampacity
Massachusetts's representative summer design ambient is around 88°F, which yields a 0.88× 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.
Massachusetts 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.