Grounding Conductor Calculator for Wyoming
NEC 2017 grounding conductor math for EV charger installers working in Wyoming.
EGC sizing in Wyoming follows NEC 2017 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 Wyoming
For a 100 A EVSE branch, Table 250.122 calls for a minimum #8 Cu equipment grounding conductor. If you upsize the phase conductors for voltage drop in Wyoming's long runs, NEC 250.122(B) requires the EGC to be upsized proportionally.
Code & Utilities
The applicable code in Wyoming is the NEC 2017, which the state adopted in 2020. That includes Article 625 EVSE rules and the 125% continuous-load factor on charging branch circuits, though some 2020-cycle changes (like expanded EMS provisions) are not yet enforced statewide.
Major electric utilities serving Wyoming include Rocky Mountain Power, Black Hills Energy, Wyoming Rural Electric Cooperatives. Always verify the applicable tariff and any utility-specific requirements (CT cabinets, metering enclosures, demand limiters) at design time.
Climate & Ampacity
Wyoming's representative summer design ambient is around 90°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.
Wyoming takeaway
On DCFC sites with parallel feeder sets, each parallel raceway needs its own full-size EGC — a detail inspectors in Wyoming catch frequently on commercial submittals.