EV Charger Load Calculator for Texas
NEC 2020 ev charger load math for EV charger installers working in Texas.
Sizing an EV charger circuit in Texas starts with NEC 2020 Article 625 — the EVSE branch must be sized to 125% of the continuous load. Hot-climate hot-band states like Texas (101°F design ambient) also force a 0.82× ampacity correction at 75°C terminations.
Worked example for Texas
For a 40 A Level 2 charger on a 240 V single-phase circuit, the OCPD is sized to 50 A (40 × 1.25 = 50.0 A, rounded up to the next standard breaker). The conductor must carry 50 A after Texas's 0.82× correction — that typically lands at #8 AWG copper THWN-2 for a residential garage run, with conduit fill checked separately if you're stacking multiple home runs.
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
Always cross-check the EVSE manufacturer's listed maximum overcurrent rating; Oncor Electric Delivery may also have specific service-upgrade or load-management requirements you'll need to coordinate before final inspection.