Wire Size Calculator for Rhode Island
NEC 2020 wire size math for EV charger installers working in Rhode Island.
Wire sizing in Rhode Island is governed by NEC 2020 Table 310.16, with the state's 86°F summer ambient driving a 0.94× correction factor at 75°C terminations per Table 310.15(B)(1).
Worked example for Rhode Island
A 60 A continuous EV branch needs a conductor whose corrected ampacity meets or exceeds 60 A. In Rhode Island's 0.94× correction, that means picking a conductor whose 30°C-rated ampacity is at least 64 A. For copper THWN-2 in EMT, that typically lands at #6 AWG; aluminum requires one to two sizes larger.
Code & Utilities
The applicable code in Rhode Island is the NEC 2020, which the state adopted in 2022. 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.
Major electric utilities serving Rhode Island include Rhode Island Energy, Pascoag Utility District, Block Island Power. Each has its own service-upgrade timeline, EV rebate availability, and metering rules — confirm them before quoting commercial work.
Climate & Ampacity
Rhode Island's representative summer design ambient is around 86°F, which yields a 0.94× ampacity correction factor at 75°C terminations per NEC 310.15(B)(1). The correction is mild but still NEC-required; document it on the load calc so your inspector sees that 310.15(B) was applied.
Rhode Island 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 Rhode Island.