Grounding Conductor Calculator for Mississippi
NEC 2020 grounding conductor math for EV charger installers working in Mississippi.
EGC sizing in Mississippi follows NEC 2020 Table 250.122, indexed off the upstream OCPD rating, with parallel rules for parallel sets and increased-conductor adjustments under 250.122(B).
Worked example for Mississippi
For a 40 A EVSE branch, Table 250.122 calls for a minimum #10 Cu equipment grounding conductor. If you upsize the phase conductors for voltage drop in Mississippi's long runs, NEC 250.122(B) requires the EGC to be upsized proportionally.
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
On DCFC sites with parallel feeder sets, each parallel raceway needs its own full-size EGC — a detail inspectors in Mississippi catch frequently on commercial submittals.