Voltage Drop Calculator for South Dakota
NEC 2020 voltage drop math for EV charger installers working in South Dakota.
South Dakota 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 South Dakota
A 40 A Level 2 charger at 120 ft on 240 V single-phase #6 Cu shows roughly 2.0% drop. That's below the 3% NEC recommendation, so you'd stay at #6. South Dakota's 0.88× ampacity correction is independent of voltage drop but applies on the same conductor pick.
Code & Utilities
EV installations in South Dakota are governed by the 2020 National Electrical Code, in force since 2023. 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 South Dakota, you'll most often interconnect with Black Hills Energy, Otter Tail Power, MidAmerican Energy SD. Their make-ready, time-of-use, and demand-charge structures vary widely; pull the specific tariff before sizing service equipment.
Climate & Ampacity
South Dakota's representative summer design ambient is around 92°F, which yields a 0.88× ampacity correction factor at 75°C terminations per NEC 310.15(B)(1). 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.
South Dakota 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 South Dakota will notice any drop above 5%.