Breaker Sizing Calculator for Maine
NEC 2020 breaker sizing math for EV charger installers working in Maine.
Every EVSE branch in Maine is treated as a continuous load per NEC 2020 Article 625 — the OCPD must be sized at 125% of the EVSE's listed maximum draw.
Worked example for Maine
A 48 A continuous EV load requires a breaker rated 60 A (48 × 1.25 = 60.0 A, rounded up to the next standard size). The conductor downstream must carry that 60 A after Maine's 0.94× ampacity correction.
Code & Utilities
The applicable code in Maine 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.
In Maine, you'll most often interconnect with Central Maine Power, Versant Power, Maine Public Utilities Commission Cooperatives. Each has its own service-upgrade timeline, EV rebate availability, and metering rules — confirm them before quoting commercial work.
Climate & Ampacity
Maine's representative summer design ambient is around 84°F, which yields a 0.94× ampacity correction factor at 75°C terminations per NEC 310.15(B)(1). The correction is mild but still NEC-required; document it on the load calc so your inspector sees that 310.15(B) was applied.
Maine takeaway
Use a 100%-rated breaker only when the panel and breaker are both listed for 100% continuous duty — otherwise the 125% rule applies. Maine inspectors enforce this rigorously on Article 625 work.