Grounding Conductor Calculator for South Dakota
NEC 2020 grounding conductor math for EV charger installers working in South Dakota.
EGC sizing in South Dakota 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 South Dakota
For a 200 A EVSE branch, Table 250.122 calls for a minimum #6 Cu equipment grounding conductor. If you upsize the phase conductors for voltage drop in South Dakota's long runs, NEC 250.122(B) requires the EGC to be upsized proportionally.
Code & Utilities
EV installations in South Dakota are governed by the 2020 National Electrical Code, in force since 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 South Dakota, you'll most often interconnect with Black Hills Energy, Otter Tail Power, MidAmerican Energy SD. Their make-ready, time-of-use, and demand-charge structures vary widely; pull the specific tariff before sizing service equipment.
Climate & Ampacity
South Dakota's representative summer design ambient is around 92°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.
South Dakota takeaway
On DCFC sites with parallel feeder sets, each parallel raceway needs its own full-size EGC — a detail inspectors in South Dakota catch frequently on commercial submittals.