Breaker Sizing Calculator for Arizona
NEC 2017 breaker sizing math for EV charger installers working in Arizona.
Every EVSE branch in Arizona is treated as a continuous load per NEC 2017 Article 625 — the OCPD must be sized at 125% of the EVSE's listed maximum draw.
Worked example for Arizona
A 48 A continuous EV load requires a breaker rated 60 A (48 × 1.25 = 60.0 A, rounded up to the next standard size). The conductor downstream must carry that 60 A after Arizona's 0.75× ampacity correction.
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
Use a 100%-rated breaker only when the panel and breaker are both listed for 100% continuous duty — otherwise the 125% rule applies. Arizona inspectors enforce this rigorously on Article 625 work.