Voltage Drop Calculator for Massachusetts
NEC 2023 voltage drop math for EV charger installers working in Massachusetts.
Massachusetts EV installs frequently push past 100 ft of conductor — detached garages, parking-lot DCFC pedestals, and multifamily carport runs all add distance. NEC 2023 recommends a 3% branch / 5% total voltage-drop ceiling.
Worked example for Massachusetts
A 40 A Level 2 charger at 120 ft on 240 V single-phase #6 Cu shows roughly 2.0% drop. That's below the 3% NEC recommendation, so you'd stay at #6. Massachusetts's 0.88× ampacity correction is independent of voltage drop but applies on the same conductor pick.
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
Voltage drop is a recommendation, not a hard NEC rule — but EVSEs throttle aggressively below ~228 V on a 240 V circuit, so customers in Massachusetts will notice any drop above 5%.