Wire Size Calculator for Virginia
NEC 2020 wire size math for EV charger installers working in Virginia.
Wire sizing in Virginia is governed by NEC 2020 Table 310.16, with the state's 92°F summer ambient driving a 0.88× correction factor at 75°C terminations per Table 310.15(B)(1).
Worked example for Virginia
A 70 A continuous EV branch needs a conductor whose corrected ampacity meets or exceeds 70 A. In Virginia's 0.88× correction, that means picking a conductor whose 30°C-rated ampacity is at least 80 A. For copper THWN-2 in EMT, that typically lands at #4 AWG; aluminum requires one to two sizes larger.
Code & Utilities
The applicable code in Virginia is the NEC 2020, which the state adopted in 2021. 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 Virginia, you'll most often interconnect with Dominion Energy Virginia, Appalachian Power, Old Dominion Electric Cooperative. Their make-ready, time-of-use, and demand-charge structures vary widely; pull the specific tariff before sizing service equipment.
Climate & Ampacity
Plan EV feeders against a 92°F ambient in Virginia — the resulting NEC 310.15(B) correction of 0.88× is what trims a #6 THWN-2 down to its true continuous rating. 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.
Virginia takeaway
Don't forget conduit-fill derating per NEC 310.15(C)(1) when more than three current-carrying conductors share a raceway — a common condition on multifamily and workplace EVSE home-run racks in Virginia.