Breaker Sizing Calculator for Mississippi
NEC 2020 breaker sizing math for EV charger installers working in Mississippi.
Every EVSE branch in Mississippi 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 Mississippi
A 40 A continuous EV load requires a breaker rated 50 A (40 × 1.25 = 50.0 A, rounded up to the next standard size). The conductor downstream must carry that 50 A after Mississippi's 0.88× ampacity correction.
Code & Utilities
Mississippi currently enforces the NEC 2020 edition, 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 Mississippi, you'll most often interconnect with Entergy Mississippi, Mississippi Power, Tennessee Valley Authority. Each has its own service-upgrade timeline, EV rebate availability, and metering rules — confirm them before quoting commercial work.
Climate & Ampacity
In Mississippi, the 95°F summer ambient drives a 0.88× 75°C ampacity correction. Bake this into every Level 2 and DCFC conductor pick before you commit to a wire size. 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.
Mississippi takeaway
Use a 100%-rated breaker only when the panel and breaker are both listed for 100% continuous duty — otherwise the 125% rule applies. Mississippi inspectors enforce this rigorously on Article 625 work.