Conduit Fill Calculator for Ohio
NEC 2017 conduit fill math for EV charger installers working in Ohio.
Multifamily and workplace EV installs in Ohio routinely stack several #6 or #8 AWG home runs in shared EMT — at which point NEC 2017 Chapter 9 fill rules and 310.15(C)(1) adjustment factors both kick in.
Worked example for Ohio
Stacking 8 × #6 AWG THWN-2 home runs (each with 2 conductors + EGC) in a single EMT means the raceway sees 16 current-carrying conductors. That triggers a 0.7× ampacity adjustment, on top of Ohio's 0.88× temperature correction. Fill itself stays under the NEC 40% ceiling at roughly 1¼" EMT.
Code & Utilities
Ohio currently enforces the NEC 2017 edition, adopted in 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.
Ohio's primary EV-relevant utilities are AEP Ohio, Duke Energy Ohio, FirstEnergy, DP&L. Each has its own service-upgrade timeline, EV rebate availability, and metering rules — confirm them before quoting commercial work.
Climate & Ampacity
Ohio's representative summer design ambient is around 89°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.
Ohio takeaway
Always run the conduit-fill math first when laying out a multifamily EVSE rack — it's the constraint that most often forces a re-spec from #6 to #4 or from EMT to a larger trade size.