Breaker Sizing Calculator for South Dakota
NEC 2020 breaker sizing math for EV charger installers working in South Dakota.
Every EVSE branch in South Dakota is treated as a continuous load per NEC 2020 Article 625 — the OCPD must be sized at 125% of the EVSE's listed maximum draw.
Worked example for South Dakota
A 80 A continuous EV load requires a breaker rated 100 A (80 × 1.25 = 100.0 A, rounded up to the next standard size). The conductor downstream must carry that 100 A after South Dakota's 0.88× ampacity correction.
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
Use a 100%-rated breaker only when the panel and breaker are both listed for 100% continuous duty — otherwise the 125% rule applies. South Dakota inspectors enforce this rigorously on Article 625 work.