Grounding Conductor Calculator for Texas
NEC 2020 grounding conductor math for EV charger installers working in Texas.
EGC sizing in Texas 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 Texas
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 Texas's long runs, NEC 250.122(B) requires the EGC to be upsized proportionally.
Code & Utilities
The applicable code in Texas 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 Texas, you'll most often interconnect with Oncor Electric Delivery, CenterPoint Energy, AEP Texas, Austin Energy, CPS Energy. Their make-ready, time-of-use, and demand-charge structures vary widely; pull the specific tariff before sizing service equipment.
Climate & Ampacity
Texas's representative summer design ambient is around 101°F, which yields a 0.82× 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.
Texas takeaway
On DCFC sites with parallel feeder sets, each parallel raceway needs its own full-size EGC — a detail inspectors in Texas catch frequently on commercial submittals.