Voltage Drop Calculator for Iowa
NEC 2020 voltage drop math for EV charger installers working in Iowa.
Iowa EV installs frequently push past 100 ft of conductor — detached garages, parking-lot DCFC pedestals, and multifamily carport runs all add distance. NEC 2020 recommends a 3% branch / 5% total voltage-drop ceiling.
Worked example for Iowa
A 60 A Level 2 charger at 240 ft on 240 V single-phase #6 Cu shows roughly 5.9% drop. That's above the 3% NEC recommendation, so you'd upsize to #4 or #2 AWG to land back under 3%. Iowa's 0.88× ampacity correction is independent of voltage drop but applies on the same conductor pick.
Code & Utilities
EV installations in Iowa are governed by the 2020 National Electrical Code, in force since 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.
Major electric utilities serving Iowa include MidAmerican Energy, Alliant Energy Iowa, Iowa Association of Municipal Utilities. Always verify the applicable tariff and any utility-specific requirements (CT cabinets, metering enclosures, demand limiters) at design time.
Climate & Ampacity
Plan EV feeders against a 91°F ambient in Iowa — 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.
Iowa takeaway
Voltage drop is a recommendation, not a hard NEC rule — but EVSEs throttle aggressively below ~228 V on a 240 V circuit, so customers in Iowa will notice any drop above 5%.