EV Charger Load Calculator for Michigan
NEC 2017 ev charger load math for EV charger installers working in Michigan.
Sizing an EV charger circuit in Michigan starts with NEC 2017 Article 625 — the EVSE branch must be sized to 125% of the continuous load. Hot-climate warm-band states like Michigan (88°F design ambient) also force a 0.88× ampacity correction at 75°C terminations.
Worked example for Michigan
For a 80 A Level 2 charger on a 240 V single-phase circuit, the OCPD is sized to 100 A (80 × 1.25 = 100.0 A, rounded up to the next standard breaker). The conductor must carry 100 A after Michigan's 0.88× correction — that typically lands at #6 AWG copper THWN-2 for a residential garage run, with conduit fill checked separately if you're stacking multiple home runs.
Code & Utilities
EV installations in Michigan are governed by the 2017 National Electrical Code, in force since 2020. 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.
In Michigan, you'll most often interconnect with DTE Energy, Consumers Energy, Indiana Michigan Power. Their make-ready, time-of-use, and demand-charge structures vary widely; pull the specific tariff before sizing service equipment.
Climate & Ampacity
Michigan's representative summer design ambient is around 88°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.
Michigan takeaway
Always cross-check the EVSE manufacturer's listed maximum overcurrent rating; DTE Energy may also have specific service-upgrade or load-management requirements you'll need to coordinate before final inspection.