Wire Size Calculator for Arizona
NEC 2017 wire size math for EV charger installers working in Arizona.
Wire sizing in Arizona is governed by NEC 2017 Table 310.16, with the state's 108°F summer ambient driving a 0.75× correction factor at 75°C terminations per Table 310.15(B)(1).
Worked example for Arizona
A 100 A continuous EV branch needs a conductor whose corrected ampacity meets or exceeds 100 A. In Arizona's 0.75× correction, that means picking a conductor whose 30°C-rated ampacity is at least 134 A. For copper THWN-2 in EMT, that typically lands at #2 AWG; aluminum requires one to two sizes larger.
Code & Utilities
EV installations in Arizona are governed by the 2017 National Electrical Code, in force since 2018. 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 Arizona include Arizona Public Service, Salt River Project, Tucson Electric Power. Each has its own service-upgrade timeline, EV rebate availability, and metering rules — confirm them before quoting commercial work.
Climate & Ampacity
Plan EV feeders against a 108°F ambient in Arizona — the resulting NEC 310.15(B) correction of 0.75× 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.
Arizona 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 Arizona.